Well-defined polymeric particles with not only a controllable shape and internal nanostructures but also stimuli-responsive functions have attracted intensive attention because of their great potential in various fields. Herein, we created unique sieve-like particles with lattice arrayed switchable channels via the confined self-assembly of poly(4-vinylpyridine)-b-polystyrene-b-poly(4-vinylpyridine) (P4VP-b-PS-b-P4VP) triblock copolymers within the emulsion droplets and the subsequent swelling treatment in ethanol. It is worth noting that the hexagonally packed P4VP channels in the sieve-like particles are switched on and off by changing the solvent type, i.e., P4VP channels are switched on in ethanol and switched off in water, which can operate as a solvent-controlled chemical gate. Moreover, the well-defined sieve-like particles can be further used as scaffolds to guide the spatial arrangement of gold nanoparticles, which generates hybrid nanomaterials with controllable morphology and ordered spatial arrangement of AuNPs.

Core-shell particles with a rigid silica core and a poly(butyl acrylate) (PBA) rubber shell are used to toughen epoxy resins without loss of elastic modulus and tensile strength. Both the diameter of silica core (D) and thickness of PBA shell (Ts) of silica-PBA core-shell particles are accurately controlled by sol-gel synthesis and seed emulsion polymerization process, respectively. From the results of notched Izod impact tests, a brittle-ductile transition of these epoxy/silica-PBA composites occurs when the rubber shell thickness (Ts) exceeds a critical value (Tsbd). It is found that Tsbd increases with increasing D which implies a critical rubber content (10 wt%) in the core-shell particles or a critical Ts/D ratio (0.0375), above which all composites transit from brittle to ductile failure. The composite elastic modulus decreases with increasing Ts. However, the critical thickness values of Tsm and Tss, below which composite modulus and tensile strength, respectively, are equal to or higher than the corresponding epoxy matrix values, are both larger than Tsbd. These results prove that brittle polymers can be toughened without loss of elastic modulus and tensile strength. However, the critical surface-to-surface inter-particle distance (Lc) is controlled by both properties of the core-shell particles and polymer matrix. When the rubber shell thickness Ts > Tsbd, Lc is increased when D is decreased. But when Ts < Tsbd, the brittle-to-ductile transition cannot occur, even when Lc is less than 100 nm.

Herein, a self-supporting comb-like Si-PEG copolymer with flexible Si–O–C bonds in the main chain and pending short PEG chains as the side chain was synthesized to improve the low temperature performance and overcome the quandary between good mechanical and electrochemical properties of the polymer electrolyte in lithium-ion batteries. The tensile strength of Si-PEG polymer electrolytes (SPH15) is 0.8 MPa at 30 °C, which is high enough to inhibit the growth of lithium dendrites. The ion conductivities of Si-PEG (SPH15) are 1.2 × 10−4 S cm−1 at 30 °C and 3.2 × 10−5 S cm−1 at 10 °C, which are one order of magnitude higher than those for PEG-based copolymer electrolytes without Si doping. The assembled LiFePO4/SPH15/Li half batteries can deliver the specific capacities of 84 mA h g−1 at 10 °C and present 75% capacity retention after 500 charge–discharge cycles at 0.5C.

Herein, a self-supporting comb-like Si-PEG copolymer with flexible Si–O–C bonds in the main chain and pending short PEG chains as the side chain was synthesized to improve the low temperature performance and overcome the quandary between good mechanical and electrochemical properties of the polymer electrolyte in lithium-ion batteries. The tensile strength of Si-PEG polymer electrolytes (SPH15) is 0.8 MPa at 30 °C, which is high enough to inhibit the growth of lithium dendrites. The ion conductivities of Si-PEG (SPH15) are 1.2 × 10−4 S cm−1 at 30 °C and 3.2 × 10−5 S cm−1 at 10 °C, which are one order of magnitude higher than those for PEG-based copolymer electrolytes without Si doping. The assembled LiFePO4/SPH15/Li half batteries can deliver the specific capacities of 84 mA h g−1 at 10 °C and present 75% capacity retention after 500 charge–discharge cycles at 0.5C.

A facile, low-cost and time-saving method was proposed to prepare antibacterial polyurethane-g-polyethylene glycol (TPU-g-PEG) nanofiber composite by anchoring silver nanoparticles (AgNP) onto nanofibers via ultrasonication assistance. Firstly, antifouling PEG as bacteria-repelling component was chemically grafted onto TPU nanofibers through UV photo-graft polymerization to obtain TPU-g-PEG nanofibers; then AgNP as bactericidal component were immobilized onto the TPU-g-PEG nanofibers under the assistance of ultrasonication. Even if the nanofibers were immersed into PBS solution and incubated for 7 days, the released content of AgNP characterized by ICP-MS was 2.688 μg which was much lower than that of reference reported method. The TPU-g-PEG/Ag nanofiber composites exhibited excellent hemocompatibility, including suppression of platelet and red blood cell adhesion, the lower hemolysis ratios, and the higher blood clotting index. Importantly, the as-prepared nanofiber composites performed better antibacterial properties in vitro assays employing gram negative and positive strains, because of the bacterial resistance of the grafted PEG and the bactericidal effect of silver. Our approach has significant potential for the development of infection-resistant wound dressing.

Improving the dispersion of graphene nanosheets (GN) in a polymer matrix is a critical step in lowering the percolation threshold of nanocomposites. In this paper, an effective method based on an electrostatic assembly process is reported. Polystyrene (PS) latex was first prepared by using hexadecyl trimethyl ammonium bromide (CTAB) as a cationic surfactant, which created positive charges on the surface of the PS micelles. An in situ demulsification process was then conducted by adding negatively charged graphene oxide (GO) particles into the positively charged PS latex. Thus, GO sheets were attached spontaneously to the surfaces of PS particles through electrostatic adsorption. Followed by in situ reduction and hot pressing, the agglomeration of GN was largely prohibited by the PS microspheres and facilitated the formation of GN networks in the PS matrix. The obtained PS/GN nanocomposites exhibited excellent electrical properties with a percolation threshold as low as 0.054 vol.% GN. When the GN content reached 1.53 vol.%, the electrical conductivity was 46.32 S/m and the thermal conductivity 0.47 W/mk. This strategy represents a new environment-friendly pathway, which is also applicable for other polymer matrices, for large-scale production of polymer composites with fully interconnected graphene networks at ultra-low GN content.

The coexistence of two kinds of reactive compatibilizers at the interface in immiscible LDPE/PA6 blends, namely, polyethylene graft maleic anhydride (PE-g-MAH) with a long backbone length and polybutadiene graft maleic anhydride (PB-g-MAH) with a short backbone length, promoted the formation of a flat interface and induced a co-continuous morphology in blends containing 30 wt % PA6. The relationships between the contents and content ratios of the dual reactive compatibilizers as well as the morphologies of the resulting LDPE/PA6 blends are examined quantitatively. The morphologies of the blends are characterized by SEM and TEM combined with a selective solvent extraction process. It is found that in these systems, when the total content of the dual compatibilizers is within 20–30 wt % and the content ratio of PE-g-MAH and PB-g-MAH is within 2:1–3:1, the minor PA6 phase can also form a co-continuous morphology in the LDPE matrix. The balance between the stability (determined by in situ formed PE-g-PA6 grafted copolymer with long backbone length) and flexibility of the flat interface (determined by in situ formed PB-g-PA6 grafted copolymer with short backbone length) in the compatibilized LDPE/PA6 blends is the key factor that controls the formation of the co-continuous morphology with low PA6 contents.

Cross-linked PEG-based copolymers were obtained via synthesis of polyethylene glycol (PEG) and methoxy polyethylene glycol (MPEG) by the bridging and/or cross-linking agent of 2,4-tolylene diisocyanate (TDI) and/or hexamethylene-1,6-diisocyanate homopolymer (HDI trimer). The effects on the crystallization behaviors of the samples could be found with the changes in molecular weight of MC-PEG and molecular weight of SC-PEG in certain cross-linked density. It is revealed that the samples appear not to crystallize when the molecular weight of MC-PEG and SC-PEG are 1000 g/mol or less than that. The samples begin to crystallize when the molecular weight of either MC-PEG or SC-PEG reaches 2000 g/mol. The crystallinity of crystallized MC-PEG decreases with the increasing molecular weight of uncrystallized SC-PEG and the crystallinity of crystallized SC-PEG declines with the rise of molecular weight of uncrystallizable MC-PEG. The chains of SC-PEG (Mn = 2000 g/mol) can fold and align easilier than those of MC-PEG (Mn = 2000 g/mol), when the content of PEG is the same.

•Chitosan was modified with carboxybetaine ester brush via a ‘click’-type azlactone reaction.•The as-prepared CS switched from bactericidal during storage to antifouling before service.•The as-modified wound dressing has great potential in biomedical applications.A facile approach to functionalize chitosan (CS) non-woven surface with the bactericidal and antifouling switchable moieties is presented. Azlactone-cationic carboxybetaine ester copolymer was firstly prepared, then chemically attached onto CS non-woven surface through the fast and efficient ‘click’-type interfacial reaction between CS primary amines and azlactone moieties. The CS non-woven surface functionalized with cationic carboxybetaine esters is able to kill bacteria effectively. Upon the hydrolysis of carboxybetaine esters into zwitterionic groups, the resulting zwitterionic surface can further prevent the attachment of proteins, platelets, erythrocytes and bacteria. This CS non-woven that switches from bactericidal performance during storage to antifouling property before its service has great potential in wound dressing applications.

•Graphene/SEBS-g-MAH nanocomposites were prepared by solution mixing.•Good interfacial interaction was obtained by the “grafting to” method in the nanocomposite.•Enhanced electrical, mechanical properties were observed for the nanocomposite.Graphene was first surface modified with octadecylamine to prevent the aggregation of graphene itself and also improve the compatibility between the graphene and polymer matrix. Then it was solution mixed with SEBS grafted with maleic anhydride (SEBS-g-MAH) to prepare graphene/SEBS-g-MAH nanocomposites. FTIR results show that esterification reaction took place by a “grafting to” method between maleic anhydride group of SEBS-g-MAH and the residual hydroxyl of graphene. Rheological data indicated that storage modulus increased sharply with 0.5 wt% addition content of graphene, due to forming the network of graphene in SEBS-g-MAH. The tensile strength was enhanced by 69%, ranging from 1.94 to 3.28 MPa. The alternating current conductivity at 1 Hz of nanocomposites increased from 2.5 ×10−16 to 1.2×10−11 S/cm, compared with that of SEBS-g-MAH. The above results were attributed to the good dispersion of graphene in SEBS-g-MAH matrix and interfacial chemical interaction between graphene and SEBS-g-MAH.

•Poly(cyclooctene)-g-poly(ethylene glycol) graft copolymers are synthesized.•Both the PEG side chain length and content are tunable.•Surface roughness affects the protein resistant property of the copolymer film.•Copolymer with 60 wt.% PEG (750 g/mol) has the best protein resistant property.In our previous work [H. Shi, D. Shi et al., Polymer Chemistry 2(2011)679–684], polycyclooctene-g-PEG (PCOE-g-PEG) copolymers were synthesized via ring opening metathesis polymerization (ROMP) from PEG functionalized cyclic olefin macromonomers and cyclooctene. The grafting degree and the grafting site were easily controlled through the “grafting through” approach. The PCOE-g-PEG film surface was imparted excellent anti-protein adsorption properties. In that work, the molecular weight of PEG side chain was fixed at 750 g/mol and the neat PEG content in the copolymer was lower than 50 wt.%. In this work, both the effects of PEG side chain lengths (350 to 1000 g/mol) at a fixed PEG content (50 wt.%) and the neat PEG content (30 wt.% to 70 wt.%) at a fixed PEG molecular weight (750 g/mol) on the anti-protein adsorption and anti-platelet adhesion properties are studied. It is shown that the copolymer with 60 wt.% PEG side chains of 750 g/mol, where both PEG and PCOE form continuous morphology, is optimal to reduce the adsorption of both the bovine serum albumin (BSA) and platelet. When the PEG content reaches 70 wt.%, phase inversion happens. PEG is the continuous phase but PCOE becomes the dispersed phase. The surface roughness of the casting PCOE-g-PEG film increases. In this case, both BSA adsorption and platelet adhesion will slightly increase comparing to the sample with 60 wt.% PEG.