Chunju He

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Name: 何春菊; ChunJu He
Organization: College of Materials Science and Engineering Donghua University , China
Department: College of Materials Science and Engineering Donghua University
Title: Researcher/Professor(PhD)

TOPICS

Co-reporter:Haiye Wang, Joshua Jasensky, Nathan W. Ulrich, Junjie Cheng, Hao Huang, Zhan Chen, and Chunju He
Langmuir November 28, 2017 Volume 33(Issue 47) pp:13689-13689
Publication Date(Web):November 3, 2017
DOI:10.1021/acs.langmuir.7b03098
Novel photocurable ternary polymer networks were prepared by incorporating N-(4-hydroxy-3-methoxybenzyl)-acrylamide (HMBA) into a cross-linked thiol–ene network based on poly(ethylene glycol)diacrylate (PEGDA) and (mercaptopropyl)methylsiloxane homopolymers (MSHP). The ternary network materials displayed bactericidal activity against Escherichia coli and Staphylococcus aureus and reduced the attachment of marine organism Phaeodactylum tricornutum. Extensive soaking of the polymer networks in aqueous solution indicated that no active antibacterial component leached out of the materials, and thus the ternary thiol–ene coating killed the bacteria by surface contact. The surface structures of the polymer networks with varied content ratios were studied by sum frequency generation (SFG) vibrational spectroscopy. The results demonstrated that the PDMS Si-CH3 groups and mimic-capsaicine groups are predominantly present at the polymer–air interface of the coatings. Surface reorganization was apparent after polymers were placed in contact with D2O: the hydrophobic PDMS Si-CH3 groups left the surface and returned to the bulk of the polymer networks, and the hydrophilic PEG chains cover the polymer surfaces in D2O. The capasaicine methoxy groups are able to segregate to the surface in an aqueous environment, depending upon the ratio of HMBA/PEGDA. SFG measurements in situ showed that the antibacterial HMBA chains, rather than the nonfouling PEG, played a dominant role in mediating the antibiofouling performance in this particular polymer system.
Co-reporter:Haiye Wang, Chengfeng Zhang, Jianxiu Wang, Xiaofeng Feng, and Chunju He
ACS Sustainable Chemistry & Engineering 2016 Volume 4(Issue 7) pp:3803
Publication Date(Web):May 20, 2016
DOI:10.1021/acssuschemeng.6b00525
A series of antibiofouling amphiphilic conetwork (APCN) coatings combined with zwitterionic features are engineered by surface zwitterionization of spontaneously segregated poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) segments, where this dual-mode surface integration of both passive and active modes improves the entire antifouling efficiency against the adsorption of proteins and a widespread marine fouling organism (Phaeodactylum tricornutum). A clear difference in surface morphology and topography before and after surface zwitterionization is ascribed to the transformation of PDMAEMA to carboxlbetaine zwitterion, which promotes the phase segregation and simultaneously accelerates the migration of hydrophilic segments toward the surface. The surface morphology evolved with hydrophilic content, and the variation trend of surface roughness before and after surface zwitterionization is exactly opposite under different hydrophilic content. With regard to structure–antibiofouling relationships, the zwitterionic surface with heterogeneous morphology as well as higher zwitterion content exhibits superior antibiofouling efficiency. This design provides a novel methodology for the development of heterogeneous and zwitterionic antibiofouling conetwork, which will not only act as a breakthrough for the design and synthesis of next generation of efficient and eco-friendly antibiofouling coating but also expand the synthesis method of APCN so as to explore its application fields.Keywords: Amphiphilic conetworks (APCN); Antibiofouling; Atom transfer radical polymerization; Migration; Zwitterion
Co-reporter:Dapeng Liu, Jing Zhu, Ming Qiu, Chunju He
Separation and Purification Technology 2016 Volume 171() pp:1-10
Publication Date(Web):17 October 2016
DOI:10.1016/j.seppur.2016.07.006
•Novel zwitterionic pLysAA brushes were grafted onto PVDF membrane.•Wetting ability of the graft membranes was improved significantly.•The graft membranes exhibited excellent antifouling properties.•Water contact angle decreased from 121.6° to as low as 29.0°.•Water flux recovery ratios reached as high as 86%.In this work, antifouling poly(vinylidene fluoride) (PVDF) microfiltration membrane was fabricated via surface activation by atmosphere plasma treatment and subsequently surface-initiated atom transfer radical polymerization (SI-ATRP). Zwitterionic poly(lysine methacrylamide) (LysAA) brushes were successfully grafted onto membrane surface as confirmed by Fourier-transform infrared spectrometer (FTIR) and X-ray photoelectron spectroscopy (XPS). The wetting ability of the graft membranes was improved significantly with water contact angle decreased from 121.6° to as low as 29.0°. The graft membranes also exhibited enhanced anti-protein-fouling and anti-oil-fouling properties with water flux recovery ratios as high as 86% and 82% respectively. This work provides a substrate-independent method for the fabrication of antifouling membranes with well-defined pLysAA brushes, which may find applications in protein separation, water treatment and oil/water separation, etc.
Co-reporter:Dapeng Liu, Jing Zhu, Ming Qiu and Chunju He  
RSC Advances 2016 vol. 6(Issue 66) pp:61434-61442
Publication Date(Web):15 Jun 2016
DOI:10.1039/C6RA09850A
Antifouling PVDF membranes were fabricated through the covalent binding of lysine methacrylamide (LysAA) brushes on the membrane surface via mussel-inspired surface-initiated atom transfer radical polymerization (SI-ATRP). The zwitterionic pLysAA brushes were immobilized on the membrane surface as well as the inner pore surface, which was conducive to enhance the hydrophilicity and separation properties of PVDF membranes due to the strong hydration capacity of zwitterions and amide groups in the brushes. Upon modification, the wetting and antifouling properties of the graft membranes were improved significantly with the water contact angle reduced to as low as 37° and the water flux recovery ratio increased to as high as 95%. This work provides an effective alternative to the traditional poly(ethylene glycol) or poly(betaine)-based materials for the fabrication of low-fouling membranes, which may find its application in blood purification, protein separation and water treatment.
Co-reporter:Xinzhen Zhao, Yongliang Chen, Huixia Xuan and Chunju He  
New Journal of Chemistry 2016 vol. 40(Issue 1) pp:441-446
Publication Date(Web):25 Sep 2015
DOI:10.1039/C5NJ02030A
This work presented a novel kind of one-dimensional multi-functional modifier for membrane materials. Cysteine modified silver nanowires (C-AgNWs) were used to modify polyvinylidene fluoride (PVDF) membranes and the comprehensive optimized properties including separation efficiency, mechanical strength and antifouling ability of PVDF membranes demonstrated that monodisperse, orientated and zwitterionic C-AgNWs were an efficient modifier for the PVDF ultrafiltration membrane. The objective of this work was to comprehensively improve the application performance of polymer materials using the special hybrid mechanism of one-dimensional nanomaterials.
Co-reporter:Haiye Wang, Xinzhen Zhao, Chunju He
Separation and Purification Technology 2016 Volume 166() pp:1-8
Publication Date(Web):22 June 2016
DOI:10.1016/j.seppur.2016.04.016
•Dual-mode nanoparticles were fabricated for hybrid.•Hybrid PVDF membranes exhibit fouling repulsion and release properties.•Hybrid PVDF membranes exhibit improved antifouling ability.The polydimethylsiloxane modified silica (SiO2-g-PDMS) nanoparticles with hydrophilic core and hydrophobic shell are employed for the hybridization modification of PVDF ultrafiltration membrane to improve the separation and antifouling performances. The results suggest the modified SiO2-g-PDMS nanoparticles exhibit improved dispersion and significant amphiphilic characteristics, and the wetting properties of membrane surface and mimetic matrix of hybrid PVDF membranes are distinctly different with the contact angle values at 105° and 15°, respectively. In addition, the added SiO2-g-PDMS nanoparticles significantly improve the fouling repulsion and fouling release properties of hybrid PVDF membranes, the anti-adsorption ability and water flux recovery ratio (FRR-W) of hybrid PVDF membranes to the two typical pollutants of bovine serum albumin (BSA) and humic acid (HA) have been significantly improved. This article aims to provide a simple way to improve the antifouling performance of PVDF ultrafiltration membrane with dual-mode multi-functional modifier.
Co-reporter:Li Zhang;Xinzhen Zhao;Dapeng Liu;Haiye Wang
Journal of Applied Polymer Science 2016 Volume 133( Issue 6) pp:
Publication Date(Web):
DOI:10.1002/app.42985

ABSTRACT

An amphiphilic co-network (APCN) membrane has been synthesized through end-crosslinking of amphiphilic grafts of polyvinylpyrrolidone (PVP) backbone carrying polydimethylsiloxane (PDMS) branches fitted with terminal vinylsilyl groups via free radical polymerization. The synthesis strategy has been carried out by the free radical polymerization of N-vinylpyrrolidone (VP) with methacrylate allyl terminated polydimethylsiloxane (MA-PDMS-V) and dimethacrylate terminated polydimethylsiloxane (MA-PDMS-MA) to form a soluble graft consisting of PVP main chains carrying vinyl terminated PDMS branches, which is crosslinked with polymethylhydrosiloxane through hydrosilylation. The resulting APCN membrane exhibited a combination of unique properties, that is, high transparency, high mechanical properties, and high permeation rate to inulin. Notably, the mechanical properties and inulin permeability of fabric-support APCN membrane were higher than that of pure APCN membrane. As a result of their unique performance, the resulting APCN membranes showed a wide range of potential applications in drug release vectors, soft contact lenses, and biomedical separation materials. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42985.

Co-reporter:Haiye Wang, Xinzhen Zhao, Chunju He
Materials Letters 2016 Volume 182() pp:376-379
Publication Date(Web):1 November 2016
DOI:10.1016/j.matlet.2016.06.075
•HSiO2 microspheres were used to prepare hybrid PVDF ultrafiltration membrane for the first time.•HSiO2 microspheres constructed stepped channels in membrane matrix.•HSiO2 improved the separation performance and fouling resistance of PVDF membrane.Hybrid polyvinylidene fluoride (PVDF) ultrafiltration membranes were prepared using hollow silica microspheres (HSiO2) as an extraordinary additive. The results showed that HSiO2 microspheres had inner cavity structure, mesoporous wall, good dispersion and excellent hydrophilicity, and could be used to construct stepped permeable channels for decreasing the mass transfer resistance of water molecules in the porous support layer of PVDF membrane. The improved hydrophilicity and constructed channels of PVDF matrix by added HSiO2 improved the separation and antifouling performance of hybrid PVDF membrane, which were conducive to increase the separation efficiency and prolong the service life of membrane module.
Co-reporter:Bomou Ma;Xue Qiao;Xiuliang Hou
Journal of Applied Polymer Science 2016 Volume 133( Issue 32) pp:
Publication Date(Web):
DOI:10.1002/app.43798

ABSTRACT

In the present study, regenerated cellulose membrane with “imprinted morphology” and low crystallinity was fabricated from the crystal cellulose/[Bmim]Cl solution. Spherulites of 1-butyl-3-methilimidazolium chloride ([Bmim]Cl) and cellulose/[Bmim]Cl solution were observed using polarized optical microscopy under certain condition. The fabricated cellulose membranes presented some particular characteristics compared with the membrane prepared from traditional cellulose/[Bmim]Cl solution. All the fabricated membranes were characterized by optical microscope, Wide-angle X-ray diffraction (WAXD), thermo-gravimetric analysis, and mechanical testing. The images showed that the resulting membranes prepared from crystal cellulose/[Bmim]Cl solution were “imprinted” with patterns which originated from the crystalline structure of [Bmim]Cl. The results of WAXD showed that the obtained cellulose membrane exhibited low diffraction peaks and crystallinity of approximately 24.57%. Furthermore, the low crystallinity led to the low mechanical property (27.5 MPa), thermal stability (315.4 °C), and high moisture regain (9.5%). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43798.

Co-reporter:Dapeng Liu;Tianbai Wang
Journal of Materials Science 2016 Volume 51( Issue 16) pp:7383-7394
Publication Date(Web):2016 August
DOI:10.1007/s10853-016-9904-9
Membrane fouling is one of the major challenges facing widespread application of membrane technology, and antifouling membranes have the advantages of increased production capacity and decreased operation costs. In this work, polyethersulfone membrane with superior antifouling property was fabricated through the facile blending of a dual-mode amphiphilic copolymer, poly(N-methyl-D-glucamine)-block-polydimethylsiloxane-block-poly(N-methyl-D-glucamine) (PNMG-b-PDMS-b-PNMG). Surface enrichment of the amphiphilic copolymer was expected to occur during the coagulation step of the phase inversion process, which endowed the modified membranes with dual-mode antifouling ability of fouling repulsion and fouling release. Filtration experiments showed that water flux and BSA solution flux of the blend membranes were significantly enhanced. The blend membranes also showed improved antifouling properties with flux recovery ratio as high as 97 % after three cycles of BSA filtration. These results provide an effective way for the preparation of low-fouling membrane in the fields of water treatment, protein separation, and blood purification.
Co-reporter:Xinzhen Zhao and Chunju He
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 32) pp:17947
Publication Date(Web):July 28, 2015
DOI:10.1021/acsami.5b04648
On the basis of the excellent fouling resistance of zwitterionic materials, the super antifouling polyvinylidene fluoride (PVDF) membrane was efficiently prepared though one-step sulfonation of PVDF and polyaniline blend membrane in situ. The self-doped sulfonated polyaniline (SPANI) was generated as a novel zwitterionic polymer to improve the antifouling property of PVDF ultrafiltration membrane used in sewage treatment. Surface attenuated total reflection Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, surface zeta potential, and water contact angle demonstrated the successful fabrication of zwitterionic interface by convenient sulfonation modification. The static adsorption fouling test showed the quantified adsorption mass of bovine serum albumin (BSA) pollutant on the PVDF/SPANI membrane surface decreases to 3(±2) μg/cm2, and the water flux recovery ratio (FRR) values were no less than 95% for the three model pollutants of BSA, sodium alginate (SA), and humic acid (HA), which were corresponding hydrophobic, hydrophilic, and natural pollutants in sewage, respectively. This Research Article demonstrated the antifouling advantages of zwitterionic SPANI and aimed to provide a simple method for the large scale preparation of zwitterionic antifouling ultrafiltration membranes.Keywords: antifouling; membrane fouling; polyvinylidene fluoride; sulfonated polyaniline; zwitterionic surface
Co-reporter:Aiwen Qin, Xiang Li, Xinzhen Zhao, Dapeng Liu, and Chunju He
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 16) pp:8427
Publication Date(Web):March 25, 2015
DOI:10.1021/acsami.5b00978
A highly hydrophilic PVDF membrane was fabricated through chemically binding TiO2 nanoparticles and a poly(vinyl alcohol) (PVA) layer onto a membrane surface simultaneously. The chemical composition of the modified membrane surface was determined by X-ray photoelectron spectroscopy, and the binding performance of TiO2 nanoparticles and the PVA layer was investigated by a rinsing test. The results indicated that the TiO2 nanoparticles were uniformly and strongly tailored onto the membrane surface, while the PVA layer was firmly attached onto the surface of TiO2 nanoparticles and the membrane by adsorption-cross-linking. The possible mechanisms during the modification process and filtration performance, i.e., water permeability and bovine serum albumin (BSA) rejection, were investigated as well. Furthermore, antifouling property was discussed through multicycles of BSA solution filtration tests, where the flux recovery ratio was significantly increased from 20.0% for pristine PVDF membrane to 80.5% for PVDF/TiO2/PVA-modified membrane. This remarkable promotion is mainly ascribed to the improvement of surface hydrophilicity, where the water contact angle of the membrane surface was decreased from 84° for pristine membrane to 24° for PVDF/TiO2/PVA membrane. This study presents a novel and varied strategy for immobilization of nanoparticles and PVA layer on substrate surface, which could be easily adapted for a variety of materials for surface modification.Keywords: antifouling property; poly(vinyl alcohol); polyvinylidene fluoride; surface modification; TiO2;
Co-reporter:Xiang Li, Aiwen Qin, Xinzhen Zhao, Dapeng Liu, Haiye Wang and Chunju He  
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 34) pp:21856-21865
Publication Date(Web):13 Jul 2015
DOI:10.1039/C5CP02498F
Drawing to change the structural properties and cyclization behaviors of the polyacrylonitrile (PAN) chains in crystalline and amorphous regions is carried out on PAN and PAN/carbon nanotube (CNT) composite fibers. Various characterization methods including Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction and thermal gravimetric analysis are used to monitor the structural evolution and cyclization behaviors of the fibers. With an increase of the draw ratio during the plasticized spinning process, the structural parameters of the fibers, i.e. crystallinity and planar zigzag conformation, are decreased at first, and then increased, which are associated with the heat exchange rate and the oriented-crystallization rate. A possible mechanism for plasticized spinning is proposed to explain the changing trends of crystallinity and planar zigzag conformation. PAN and PAN/CNT fibers exhibit various cyclization behaviors induced by drawing, e.g., the initiation temperature for the cyclization (Ti) of PAN fibers is increased with increasing draw ratio, while Ti of PAN/CNT fibers is decreased. Drawing also facilitates cyclization and lowers the percentage of β-amino nitrile for PAN/CNT fibers during the stabilization.
Co-reporter:Xiang Li, Xiaofei Ji and Chunju He  
RSC Advances 2015 vol. 5(Issue 99) pp:81399-81406
Publication Date(Web):09 Sep 2015
DOI:10.1039/C5RA14391H
The morphological and structural properties of plasticized spinning polyacrylonitrile (PAN) fibers during the stabilization process were investigated. The PAN fibers were subjected to stabilization treatment following a three-stage heating process. The PAN fibers were characterized by elemental analysis, Fourier transform infrared spectroscopy and X-ray diffraction; it was found that the stabilization degree of the PAN fibers is significantly higher than that of commercial PAN fibers. For plasticized spinning fibers, stabilization can occur in the crystalline region even at a low temperature of 180 °C; oxygen containing groups in the crystalline region generated during the plasticized spinning process may be responsible for this phenomenon. At a stabilization temperature of 230 °C, the cross-section of plasticized spinning fibers exhibits a large block stacking structure with obvious grooves among them, whereas a cross-section of the fibers shows a sheet-like divergence structure at 260 °C. The mechanical properties and density test results further indicate that 260 °C is a critical stabilization temperature for plasticized spinning fibers. Moreover, it is observed that a slight skin-core structure can be formed during the stabilization process.
Co-reporter:Xinzhen Zhao, Huixia Xuan and Chunju He  
RSC Advances 2015 vol. 5(Issue 99) pp:81115-81122
Publication Date(Web):18 Sep 2015
DOI:10.1039/C5RA15719F
Branched polyethylene glycol (PEG) was anchored onto a membrane surface by efficient covalent self-assembly to optimize the separation and antifouling properties of polyvinylidene fluoride (PVDF) ultrafiltration membranes based on its excellent hydrophilic and antifouling properties. The results showed that the surface self-assembly method could effectively improve the stability of PEG and the surface wetting ability of the PVDF membrane, and simultaneously enhanced the water flux and rejection of modified membranes. Meanwhile, the fouling results showed the anchored PEG segments on the separation interface contributed to improve the antifouling performance of the PVDF ultrafiltration membrane with significantly improved anti-adsorption capacity for bovine serum albumin (BSA) and expectant water flux recovery ratios for BSA and humic acid (HA), two typical pollutants. This paper provides a sample modification idea and demonstrated covalent self-assembly was an effective method for surface modification.
Co-reporter:Yongliang Chen, Xinzhen Zhao and Chunju He  
RSC Advances 2015 vol. 5(Issue 84) pp:68998-69005
Publication Date(Web):29 Jul 2015
DOI:10.1039/C5RA07150J
Polydimethylsiloxane-graft-polyethylene glycol (PDMS-graft-PEG), an amphiphilic polymer with four hydrophilic arms, was prepared and used to improve the antifouling property of PVDF membranes by a dip-coating method. The interface properties of the modified PVDF membranes were investigated and it was found that the increased molecular weight of the PEG segment exhibited a negative effect on the anchoring ability of the PDMS-graft-PEG on the membrane surface. However, the antifouling properties of the modified membranes were significantly improved due to the dual-mode antifouling ability of fouling repulsion (PEG) and fouling release (PDMS). The adsorption mass of BSA on the modified membrane surface decreased to a low level, and an enhanced water flux recovery ratio after washing (FRR-W) of the modified membranes was obtained for two typical pollutants of bovine serum albumin and sodium alginate. It was demonstrated that surface anchoring is an effective way to improve the interface characteristics of membrane materials with functional polymers.
Co-reporter:Xinzhen Zhao, Huixia Xuan, Aiwen Qin, Dapeng Liu and Chunju He  
RSC Advances 2015 vol. 5(Issue 79) pp:64526-64533
Publication Date(Web):24 Jul 2015
DOI:10.1039/C5RA08705H
In this work, a novel modification method was introduced to improve the antifouling property of polyvinylidene fluoride (PVDF) ultrafiltration membranes, which were prepared with a one-pot process using plasma pretreatment and graft polymerization of PVDF powder. The amphiphilic copolymer of polyvinylidene fluoride-g-polyacrylic acid (PVDF-g-PAA) present in the modified PVDF membrane was demonstrated by infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). The improved wetting ability was conducive to improve the water flux, bovine serum albumin rejection and antifouling ability of modified PVDF membranes. A totally novel pH quantitative method was employed to investigate the antifouling property based on the acid–base reaction of the amino acid residues of BSA (pollutant), according to the detected change of BSA adsorption amount on membrane surface and pore surface before and after modification, less irreversible fouling was detected in the modified PVDF membrane due to the existence of PVDF-g-PAA, and it was more convenient to remove the pollutants in the pores of modified PVDF membranes by water flushing.
Co-reporter:Xinzhen Zhao, Aiwen Qin, Dapeng Liu and Chunju He  
RSC Advances 2015 vol. 5(Issue 78) pp:63580-63587
Publication Date(Web):20 Jul 2015
DOI:10.1039/C5RA08041J
The polyelectrolyte complex (PEC) layer fabricated by chitosan and sodium alginate was anchored on a membrane surface though plasma treatment and layer by layer self-assembly to improve the antifouling properties of the PVDF membrane. The interface properties of modified PVDF membranes were investigated and the results indicated the presence of the PEC layer was conducive to enhance the hydrophilicity and screening ability of the PVDF ultrafiltration membrane due to the hydrophilic crosslinking structure. Furthermore, the fouling resistance including anti-adsorption ability and dynamic antifouling ability for pollutant filtration of modified PVDF membranes were significantly improved due to the anchored PEC layer. For the CS–SA-3 membrane with an assembly number of 3, the adsorption mass of BSA on the membrane surface was only 4 μg cm−2 and the FRR-W values increased to 89%, 99% and 98% for the three typical pollutants of bovine serum albumin, sodium alginate and humic acid, respectively. It was demonstrated that the PEC layer could be used as an antifouling material to improve the antifouling ability of hydrophobic membranes though decreasing the reversible fouling. This article also aimed to provide a simple method to fabricate the antifouling interface.
Co-reporter:Jing Zhu, Xinzhen Zhao and Chunju He  
RSC Advances 2015 vol. 5(Issue 66) pp:53653-53659
Publication Date(Web):03 Jun 2015
DOI:10.1039/C5RA05571G
Hybrid polyvinylidene fluoride (PVDF) ultrafiltration (UF) membranes with excellent antifouling properties were prepared by non-solvent-induced phase separation through blending zwitterionic SiO2 nanoparticles. Lysine was used to modify SiO2 nanoparticles to generate a surface zwitterion of the amino acid type. Zwitterionic SiO2 nanoparticles were distributed uniformly in the membrane bulk to avoid massive agglomeration and to significantly improve the hydrophilicity and separation performance of PVDF UF membranes. The amount of BSA adsorbed on a hybrid ZP-5% membrane surface of static fouling test decreased to 10 μg cm−2, and the secondary water flux recovery rate (FRR) increased to more than 95% for the dynamic antifouling test of BSA and HA. The addition of zwitterionic SiO2 nanoparticles enhanced the antifouling ability of the membrane through inhibiting irreversible fouling and prolonging the service life of the PVDF UF membrane.
Co-reporter:Xiang Li, Xiaofei Ji, Aiwen Qin and Chunju He  
RSC Advances 2015 vol. 5(Issue 64) pp:52226-52234
Publication Date(Web):03 Jun 2015
DOI:10.1039/C5RA05696A
The plasticized spinning and cyclization behaviors of polyacrylonitrile (PAN) and polyacrylonitrile/functionalized carbon nanotube (PAN/CNT-COOH) composite fibers were studied. The PAN/CNT-COOH fibers containing 0.8 wt% CNTs exhibit excellent tensile strength and modulus, i.e. 0.475 GPa and 10.93 GPa, which are 69.6% and 40.13% improvement respectively, compared to their precursor fibers. The changing trend of crystallinity of PAN/CNT-COOH fibers is associated with the heat exchange rate and oriented-crystallization rate, which can be confirmed by the X-ray diffraction (XRD) results. The cyclization behaviors of the fibers were examined using X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The results show that cyclization of PAN/CNT-COOH fibers is initiated by three types of initiating agents, i.e., modified CNTs (CNTs-COOH), oxygen containing groups generated during the plasticized spinning and comonomers. Meanwhile, the PAN/CNT-COOH fibers exhibit various cyclization behaviors induced by high spinning speeds.
Co-reporter:Ming Qiu, Xin-Zheng Zhao, Da-Peng Liu and Chun-Ju He  
RSC Advances 2015 vol. 5(Issue 23) pp:17851-17861
Publication Date(Web):22 Dec 2014
DOI:10.1039/C4RA13866J
A series of pH-responsive amphiphilic conetworks (APCNs) were synthesized through cross-linking of well-defined amphiphilic pentablock copolymers via atom transfer radical polymerization (ATRP). A new ditelechelic polydimethylsiloxane macroinitiator was synthesized to initiate the polymerization of N,N-dimethylaminoethyl methacrylate. The resulting triblock copolymers showed well-defined molecular weight with narrow polydisperisty, which were used as macroinitiator to incorporate allyl methacrylate to get the pentablock copolymers with allyl pendant groups. Then, pentablock copolymers were fully cross-linked with polyhydrosiloxanes through hydrosilylation. The so-prepared APCNs exhibited unique properties of microphase separation of hydrophilic (HI) and hydrophobic (HO) phases with small channel size, a variable swelling capacity in media with different pH and polarity, a good mechanical property (1.3 ± 0.2 MPa) and outstanding oxygen permeability (300 ± 120 barrers). The properties of APCNs depend on the ratio of HI–HO, which can be regulated via precise synthesis of the triblock copolymers. The APCNs showed well-controlled drug release to Rhodamine 6G upon varying the pH. Meanwhile, the controlled manner is also attributed to the well-defined molecular structure and tunable HI/HO composition of the APCNs.
Co-reporter:Aiwen Qin, Xiang Li, Xinzhen Zhao, Dapeng Liu, Chunju He
Journal of Membrane Science 2015 480() pp: 1-10
Publication Date(Web):
DOI:10.1016/j.memsci.2015.01.035
Co-reporter:Haiye Wang;Aiwen Qin;Xiang Li;Xinzhen Zhao;Dapeng Liu
Journal of Polymer Science Part A: Polymer Chemistry 2015 Volume 53( Issue 21) pp:2537-2545
Publication Date(Web):
DOI:10.1002/pola.27721

ABSTRACT

A series of amphiphilic conetworks (APCNs) is synthesized through crosslinking of well-defined tri-arm star diblock copolymers via atom transfer radical polymerization. A new three-arm initiator is synthesized to initiate the polymerization of 2-hydroxyethyl methacrylate (HEMA) via “core-first” method. The resulting star HEMA homopolymers with well-defined molecular weight and narrow polydispersity are used as macroinitiator to incorporate allyl methacrylate to get the star diblock copolymers. Then, the precursors with allyl pendant groups are fully crosslinked with polyhydrosiloxanes through hydrosilylation. The so-prepared APCNs exhibit unique properties of microphase separation of hydrophilic (HI) and hydrophobic (HO) phases with small channel size, a variable swelling capacity, excellent biocompatibility, and outstanding mechanical strength (2 ± 0.5 MPa). The properties of APCNs depend on the ratio of HI to HO, which can be regulated via precise synthesis of the star diblock copolymers. The APCNs show well-controlled drug release to choline theophyllinate, suggesting a promising intelligent drug carrier for controlled release. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 2537–2545

Co-reporter:Jianfeng Xu, Ming Qiu, Bomou Ma, and Chunju He
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 17) pp:15283
Publication Date(Web):August 7, 2014
DOI:10.1021/am5037252
Novel amphiphilic conetworks (APCNs) with uniform channel size were synthesized through end-cross-linking of well-defined amphiphilic triblock copolymers via atom transfer radical polymerization (ATRP). A new ditelechelic polydimethylsiloxane macroinitiator was synthesized to initiate the polymerization of N,N-dimethylacrylamide. The resulting triblock copolymers show well-defined molecular weight with narrow polydisperisty, which are telechelic modified by allylamine and fully cross-linked with polyhydrosiloxanes through hydrosilylation. Transmission electron microscopy shows that the APCN has the behavior of microphase separation with small channel size and uniform phase domain. The resulting APCNs with idealized microstructure exhibit a combination of excellent properties, i.e., superhigh mechanical strength (4 ± 1 MPa) and elongation ratio (175 ± 25%), outstanding oxygen permeability (350 ± 150 barrers), a high water uptake property, and excellent biocompatibility, indicating that in this way, “near perfect” networks are obtained. These results are better than those reported in the literature, suggesting a promising semipermeable barrier for islet encapsulation in relative biomaterial fields.Keywords: amphiphilic conetwork; atom transfer radical polymerization; membrane; oxygen permeability; polydimethylsiloxane
Co-reporter:Xiang Li, Aiwen Qin, Xinzhen Zhao, Bomuo Ma, Chunju He
Polymer 2014 Volume 55(Issue 22) pp:5773-5780
Publication Date(Web):23 October 2014
DOI:10.1016/j.polymer.2014.08.057
•[Bmim]Cl was explored as a novel plasticizer for PAN to prepare PAN fibers.•The interaction and plasticization mechanism in PAN/[Bmim]Cl system were studied.•Cyclization and oxidation reactions occurred during plasticized spinning process.•The addition of [Bmim]Cl to PAN hindered the cyclization to some extent.•Special ladder structure of PAN fibers was obtained, facilitating the stabilization.The external plasticization of polyacrylonitrile (PAN) with high molecular weight was achieved, where 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) was explored as a novel plasticizer. The interaction and plasticization mechanism in PAN/[Bmim]Cl system were investigated. The Fourier transform infrared spectroscopy (FTIR) results show that there exists strong hydrogen interaction between nitrile (CN) groups of PAN and unsaturated C–H of imidazolium rings in [Bmim]Cl at high temperature. The addition of [Bmim]Cl leads to the decrease in glass transition temperature, melting temperature and paracrystalline content of the system due to the high penetration efficiency of [Bmim]Cl. The rheology of the system was studied as well, which proves the occurrence of the cyclization and oxidation reactions of PAN macromolecular chains along with X-ray photoelectron spectrometer and FTIR results. The cyclization reaction is significantly influenced by the [Bmim]Cl content in whole system, which further affects the spinnability of PAN/[Bmim]Cl system and ladder structure of the prepared fibers.
Co-reporter:Bomou Ma, Aiwen Qin, Xiang Li, Xinzhen Zhao, Chunju He
Materials Letters 2014 120() pp: 82-85
Publication Date(Web):
DOI:10.1016/j.matlet.2014.01.015
Co-reporter:Aiwen Qin;Xueliang Wu;Bomou Ma;Xinzhen Zhao
Journal of Materials Science 2014 Volume 49( Issue 22) pp:7797-7808
Publication Date(Web):2014 November
DOI:10.1007/s10853-014-8490-y
PVDF/SiO2 hybrid membranes with outstanding antifouling property were prepared from PVDF/glycerol triacetate system via thermally induced phase separation method, and characterized by scanning electron microscope, energy dispersive X-ray spectrometer analyses, differential scanning calorimeter, and wide angle X-ray diffraction. Their properties such as permeability, porosity, pore size distribution, and mechanical performance were also determined. The results show that SiO2 nanoparticles modified by 3-aminopropyltriethoxysilane can be uniformly dispersed in membranes due to improved compatibility between PVDF solution and nanoparticles. The addition of SiO2 particles to PVDF/glycerol triacetate mixture has a strong effect on crystallinity of the resulting hybrid membrane, which does not affect the type of PVDF crystal structure. Water flux recovery ratio is significantly increased from 11.7 % for pure PVDF membrane to 93.8 % for PVDF/SiO2 hybrid membrane with addition of 8 wt% modified SiO2. This remarkable promotion is related to the implantation of SiO2 nanoparticles into the inner surface of membrane, which effectively restrains the adsorption of bovine serum albumin on the pore walls and improves antifouling property of the final membranes. Additionally, pure water flux of the hybrid membrane is increased by 276 %, i.e., from 85 to 320 L m−2 h−1, tensile strength is increased by 26.5 %, and elongation at break is increased by 85.4 % compared with that of pure membrane.
Co-reporter:Bomou Ma, Aiwen Qin, Xiang Li, Chunju He
Carbohydrate Polymers 2013 Volume 97(Issue 2) pp:300-305
Publication Date(Web):12 September 2013
DOI:10.1016/j.carbpol.2013.04.080
•Binary ionic liquid system was built as a powerful solvent for dissolving chitosan.•Regenerated chitosan fibers were prepared by dry-wet spinning technique especially.•Tensile strength of the prepared chitosan fibers reaches up to 2.1 cN/dtex•This fiber is stronger than existing fibers prepared from acetic acid solution.A binary ionic liquid system was confirmed to be a promising solvent to dissolve chitosan, and the regenerated chitosan fibers were prepared by wet and dry-wet spinning technique respectively. The SEM results show that the chitosan fibers prepared by wet spinning technique present striated surface and round cross section, and the chitosan fibers prepared by dry-wet spinning technique present smooth surface and irregular cross section. The mechanical testing results show that the regenerated chitosan fibers present relatively high tenacity, especially, these prepared by dry-wet spinning process present excellent strength and initial modulus, i.e. 2.1 cN/dtex and 83.5 cN/dtex, which is stronger than that of most reported chitosan fibers. The FT-IR results show that the dissolution of chitosan in the binary ionic liquid system is due to the protonation of NH2 groups in the chitosan chains. Furthermore, a possible reaction during the dissolution and regeneration process is proposed.
Co-reporter:Bomou Ma, Xiang Li, Aiwen Qin, Chunju He
Carbohydrate Polymers 2013 Volume 91(Issue 2) pp:477-482
Publication Date(Web):16 January 2013
DOI:10.1016/j.carbpol.2012.07.081
In this study, glycine hydrochloride (Gly·HCl) is confirmed to be a promising solvent for dissolving native chitosan and preparing regenerated chitosan membrane. As compared with the chitosan membrane prepared from traditional acetic acid, the membrane prepared from Gly·HCl by dry technique shows excellent tensile strength and initial modulus, i.e. 103.8 MPa and 3.2 GPa, respectively, which is superior to any chitosan membrane and most chitosan blend membranes reported in literatures. Besides, scanning electron microscopy (SEM), wide-angle X-ray diffraction (WAXD) and Fourier transform infrared spectroscopy (FT-IR) were used to visualize the difference between the two kind of regenerated chitosan membranes. The SEM results show that the membrane prepared from Gly·HCl by dry technique presents a novel structure, which ensures its high tenacity. Furthermore, the chitosan microporous membranes were also prepared using PEG as porogen.Highlights► Gly·HCl is a promising solvent to prepare regenerated chitosan membrane (CSM). ► The prepared CSM presents a novel structure and superior mechanical performance. ► The chitosan microporous membranes (CSMMs) were prepared using PEG as porogen. ► The morphology of CSMMs prepared from Gly·HCl and acetic acid is different.
Co-reporter:Bomou Ma, Aiwen Qin, Xiang Li, and Chunju He
Industrial & Engineering Chemistry Research 2013 Volume 52(Issue 27) pp:9417-9421
Publication Date(Web):June 12, 2013
DOI:10.1021/ie401097d
In this paper, 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) was synthesized and used as solvent to dissolve bamboo pulp. Dimethylsulfoxide (DMSO) was selected as cosolvent to adjust the solution viscosity. As compared with the bamboo pulp/[Bmim]Cl system, the addition of DMSO decreases the solution viscosity dramatically. Afterward, cellulose hollow fiber membranes were prepared by dry-wet spinning process using 75 wt % [Bmim]Cl + 25 wt % DMSO as solvent. Scanning electron microscope (SEM), mechanical testing, pure water permeability, and retention rate were used to characterize its properties, respectively. The SEM result shows that the prepared cellulose hollow fiber membrane presents dense surface structure, which leads to a relative high tensile strength and retention rate to bovine serum albumin, i.e. 28 MPa and 98%, respectively, but a relative low pure water permeability, i.e. 83 L/m2·h. In the end, the [Bmim]Cl is recovered by azeotropy, and the recycling yield reaches 99 wt %.
Co-reporter:Bomou Ma, Meng Zhang, Chunju He, Junfen Sun
Carbohydrate Polymers 2012 Volume 88(Issue 1) pp:347-351
Publication Date(Web):17 March 2012
DOI:10.1016/j.carbpol.2011.12.020
A binary system consisting of acidic ionic liquid glycine hydrochloride (Gly·HCl) and neutral ionic liquid 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) is proposed to be cosolvent for chitosan and cellulose, the spinning solution of chitosan/cellulose can be prepared in one step. The regenerated chitosan/cellulose composite fiber with 9.4 wt.% chitosan was prepared through dry–wet spinning process. SEM shows that the chitosan is scattered on the surface and interior of the composite fiber. WAXD shows that the degree crystallization of the composite fibers is far less than that of raw materials. The result of elemental analysis (EA) indicates that there is little weight loss of chitosan during the spinning process. Moreover, the prepared composite fiber presents good thermal stability, i.e. its Tonset is 305.1 °C, and excellent mechanical property, i.e. its tensile strength is 4.63 cN/dtex. All the results show that Gly·HCl/[Bmim]Cl binary system is a promising solvent for the preparation of chitosan/cellulose composite fiber.Highlights► A binary solvent system presents strong dissolving power for chitosan and cellulose. ► The spinning solution including chitosan and cellulose can be prepared in one step. ► The prepared composite fibers via solution spinning present good mechanical property.
Co-reporter:Li Tang, Xiang Li, De Du, Chunju He
Progress in Natural Science: Materials International 2012 Volume 22(Issue 4) pp:341-346
Publication Date(Web):August 2012
DOI:10.1016/j.pnsc.2012.06.005
A key challenge in the preparation of nanoplatelet-filled polymer composites is the ability to realize the nanometer-level dispersion and the planar orientation of nanosheets in polymer matrices. In this report, multilayer films were successfully fabricated by layer-by-layer assembly of regenerated cellulose and graphene oxide, in which graphene oxide nanosheets were used as the building blocks. The thickness of 50 layer film is about 20 μm and it exhibits a high degree of smoothness. This may be attributed to the well-defined layered structure with high degree of planar orientation and nanolevel assemblies of graphene oxide nanosheets in the polymer matrices. Typical field emission scanning electron microscope images demonstrate an ordered arrangement of layers. The electrical conductivity of the multilayer films shows a remarkable increase with increasing layer of the films. A significant enhancement of mechanical properties has been achieved, that is, a 110.8% improvement of elastic modulus and a 262.5% increase of hardness respectively.
Co-reporter:Chunju He;Bomou Ma
Polymers for Advanced Technologies 2010 Volume 21( Issue 7) pp:496-505
Publication Date(Web):
DOI:10.1002/pat.1458

Abstract

The aim of this paper is the preparation and characterization of cellulose/chitin blend filaments over the experimental blend ratio scope i.e., 2.89 and 6.46% (w/w) chitin content through high wet modulus (HWM) procedure. The spinnability of the invested solutions was found to vary in the following order: chitin < cellulose < 9.5:0.5 blend < 9:1 blend < 8:2 blend < 5:5 blend (9:1 means the mass ratio of cellulose to chitin, so does 9.5:0.5, 8:2, and 5:5). The cross-section of the blend filaments is of chrysanthemum shape. It was shown through the SEM photographs that there existed grooves on the surface of filaments, which became coarse with increase in chitin content. Based on the data from X-ray, sonic velocity, intensity, and hygroscopicity, it is concluded that the degree of crystallinity, dry and wet intensity modulus, degree of orientation, and regain rate of the filaments decreased with increase in chitin content in the experiment scope. The mechanical properties of the blend filaments are much higher than those of Crabyon fiber and normal viscose filaments, which proves that the HWM method is an efficient way of preparing cellulose/chitin blend filaments with satisfactory mechanical properties and processing property. The blend filaments prepared have an effective biostatic effect on Staphylococcus aureus, Escherchia coli, and Corinebaterium michiganence according to different testing standards. Copyright © 2009 John Wiley & Sons, Ltd.

Co-reporter:Chunju He;Bomou Ma;Junfen Sun
Journal of Applied Polymer Science 2009 Volume 113( Issue 5) pp:2777-2784
Publication Date(Web):
DOI:10.1002/app.29746

Abstract

The focus of this article is the preparation and characterization of cellulose/chitin blend filaments obtained from cellulose/chitin xanthate blend solution over the experimental blend ratio, i.e., 2.89% and 6.46% (w/w) chitin content. The addition of chitin xanthate into cellulose xanthate leads to an increase of intermittence rate and the blend solution has good filtering property. Scanning electronic microscope photos shows that there exist grooves on the filaments surface, which are becoming coarse with increasing chitin content. The mechanical properties of the spun blend filaments is much higher than that of Crabyon® fiber, which proves that the viscose method we adopt here is an efficient way to prepare cellulose/chitin blend filaments with satisfactory mechanical properties and processing property. Based on the data from X-ray, sonic velocity, equilibrium regain rate, and accessibility, it is concluded that the degree of crystallinity, modulus, degree of orientation, density, equilibrium regain rate, and accessibility of blend filaments decreases with increasing chitin content in the blend filaments in the experiment scope. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Co-reporter:Chunju He;Junfen Sun;Bomou Ma;Qingrui Wang
Journal of Applied Polymer Science 2008 Volume 110( Issue 2) pp:1208-1215
Publication Date(Web):
DOI:10.1002/app.28559

Abstract

The focus of this article is the rheological properties of cellulose xanthate, chitin xanthate, and their blend solutions with cellulose/chitin blend weight ratios of 9.5 : 0.5, 9 : 1, 8 : 2, and 5 : 5 (mostly 9 : 1 blend solutions). The preparation and properties of fibers from 9 : 1 blend solutions and cellulose xanthate solutions are also discussed. The non-Newtonian index of the investigated solutions was found to vary in the following order: chitin < cellulose < 9.5 : 0.5 blend < 9 : 1 blend < 8 : 2 blend < 5 : 5 blend. Showing a tendency contrary to that of the non-Newtonian index, the structure viscosity index varies in the following order: chitin > cellulose > 9.5 : 0.5 blend > 9 : 1 blend > 8 : 2 blend > 5 : 5 blend. For 5–9 wt % 9 : 1 blend solutions, increasing the solution temperature aids the improvement of the fluidity of 9 : 1 blend solutions in the temperature range of 10–40°C. The zero shear viscosity decreases in an index manner with the solution temperature increasing. The 7–8 wt % 9 : 1 blend solutions have good filtering and rheological properties and are ideal for spinning fibers. The mechanical properties of blend fibers spun from 7% 9 : 1 blend solutions are lower than those of pure cellulose and are much higher than those of Crabyon fiber, and they still reach the national criteria and fit the need for further processing. This proves that the viscose method which we have developed here is an efficient way of preparing cellulose/chitin blend fibers with satisfactory mechanical properties and processing properties. Scanning electron microscopy photographs show that the surface of 9 : 1 blend fibers is coarser than that of pure cellulose fibers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Co-reporter:Chun-Ju He;Jun-Fen Sun;Qing-Rui Wang;Si-Jun Zhu
Journal of Applied Polymer Science 2007 Volume 105(Issue 6) pp:3708-3714
Publication Date(Web):11 JUN 2007
DOI:10.1002/app.25924

Different membrane forming conditions including solid content, spinning solution temperature, the pressure of internal quench medium, concentration of coagulation bath, and winding-up velocity, etc. have different influence on the structure and physical properties of PES hollow fiber membranes prepared. Membrane properties i.e., void content and water flux decrease with increasing content of PES in the spinning solution. Water flux reaches a maximum while retention reaches a minimum when spinning solution temperature reaches 35°C. Water flux, inner and outer diameters increase and wall thickness decreases with increasing pressure of internal quench medium. Water flux reaches a minimum when the concentration of coagulation bath reaches 20%. The inner diameter of hollow fiber membrane increases and outer diameter does not change with increasing 1st godget velocity. The inner and outer diameters and membrane wall thickness decrease with increasing winding-up velocity. The clearance of creatinine and urea reaches 92 and 86% respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007

Co-reporter:Feng-Jian Pang;Chun-Ju He;Qing-Rui Wang
Journal of Applied Polymer Science 2003 Volume 90(Issue 12) pp:3430-3436
Publication Date(Web):14 OCT 2003
DOI:10.1002/app.13063

The blend solution of cellulose xanthate with chitin xanthate has excellent filtering property as an ordinary cellulose viscose. The SEM photos show that the fiber surface becomes coarse with increasing chitin content. The X-ray diffraction shows that the addition of chitin interferes with the crystallization of cellulose. The dry and wet strength and density of blend fibers decrease with increasing chitin content. The hygroscopicity of the blend staples decreases with increasing chitin content, and there exists a minimum at 3.85% chitin mass percent, while the accessibility shows the same tendency. The fiber prepared has effective bacteriostatic effects on Staphylococcus aureus, Escherchia coli, etc., and the bacteriostastic rate increases with increasing chitin content. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3430–3436, 2003

Co-reporter:Haiye Wang, Xinzhen Zhao, Chunju He
International Journal of Biological Macromolecules (June 2016) Volume 87() pp:443-448
Publication Date(Web):1 June 2016
DOI:10.1016/j.ijbiomac.2016.02.074
A novel zwitterionic surface of PVDF membrane with significantly improved antifouling properties was prepared though pressure-assisted layer by layer self-assembly method based on the electrostatic interactions of chitosan (CS), sodium alginate (SA) and polyfunctional lysine. For the modified C-S-C-S-L membrane, the contact angle decreased to 35°, the bovine serum albumin (BSA) adsorption mass of static fouling on the membrane surface decreased to 10 μg/cm2, and the secondary water flux recovery rate (FRR) of dynamic fouling of BSA and humic acid (HA) pollutants increased to 98% and 99%, respectively, exhibiting excellent antifouling performance. The results demonstrated that using charged bio-macromolecules and amino acids to build zwitterionic surface was effective and convenient to change the interface properties of the separation membrane through the pressure-assisted self-assembly modification method, and provided a new way for the industrial scale hydrophilic modification of hydrophobic porous membrane materials.Download high-res image (148KB)Download full-size image
Co-reporter:Xiang Li, Aiwen Qin, Xinzhen Zhao, Dapeng Liu, Haiye Wang and Chunju He
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 34) pp:NaN21865-21865
Publication Date(Web):2015/07/13
DOI:10.1039/C5CP02498F
Drawing to change the structural properties and cyclization behaviors of the polyacrylonitrile (PAN) chains in crystalline and amorphous regions is carried out on PAN and PAN/carbon nanotube (CNT) composite fibers. Various characterization methods including Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction and thermal gravimetric analysis are used to monitor the structural evolution and cyclization behaviors of the fibers. With an increase of the draw ratio during the plasticized spinning process, the structural parameters of the fibers, i.e. crystallinity and planar zigzag conformation, are decreased at first, and then increased, which are associated with the heat exchange rate and the oriented-crystallization rate. A possible mechanism for plasticized spinning is proposed to explain the changing trends of crystallinity and planar zigzag conformation. PAN and PAN/CNT fibers exhibit various cyclization behaviors induced by drawing, e.g., the initiation temperature for the cyclization (Ti) of PAN fibers is increased with increasing draw ratio, while Ti of PAN/CNT fibers is decreased. Drawing also facilitates cyclization and lowers the percentage of β-amino nitrile for PAN/CNT fibers during the stabilization.
2-?Propenoic acid, 2-?methyl-?, 2-?(dimethylamino)?ethyl ester, polymer with 1,?1'-?[2-?ethyl-?2-?[[(2-?mercaptoacetyl)?oxy]?methyl]?-?1,?3-?propanediyl] bis(2-?mercaptoacetate) and 2-?propen-?1-?yl 2-?methyl-?2-?propenoate
2-?Propenoic acid, 2-?methyl-?, 2-?propen-?1-?yl ester, polymer with 1,?1'-?[2,?2-?bis[(3-?mercapto-?1-?oxopropoxy)?methyl]?-?1,?3-?propanediyl] bis(3-?mercaptopropanoate) and 1-?ethenyl-?2-?pyrrolidinone
2-?Propenoic acid, 2-?propen-?1-?yl ester, polymer with 1,?1'-?[2-?ethyl-?2-?[(3-?mercapto-?1-?oxopropoxy)?methyl]?-?1,?3-?propanediyl] bis(3-?mercaptopropanoate) and N-?(1-?methylethyl)?-?2-?propenamide
2-?Propenoic acid, 2-?methyl-?, 2-?propen-?1-?yl ester, polymer with 1,?1'-?[2,?2-?bis[(3-?mercapto-?1-?oxopropoxy)?methyl]?-?1,?3-?propanediyl] bis(3-?mercaptopropanoate) and N-?(1-?methylethyl)?-?2-?propenamide
2-?Propenoic acid, 2-?propen-?1-?yl ester, polymer with 1-?ethenyl-?2-?pyrrolidinone and 1,?1'-?[2-?ethyl-?2-?[(3-?mercapto-?1-?oxopropoxy)?methyl]?-?1,?3-?propanediyl] bis(3-?mercaptopropanoate)
2-?Propenoic acid, 2-?methyl-?, (2S)?-?2-?amino-?2-?carboxyethyl ester, polymer with 1,?1-?difluoroethene, graft
2-Propenoic acid, 3-(1,1,3,3-tetramethyldisiloxanyl)propyl ester