•An isothermal crystallization fractionation method is reported for trans-1,4-poly(isoprene-co-butadiene) copolymers (TBIR).•TBIR-15 and TBIR-20 are multi-block copolymers, while TBIR-40 is random copolymer.Polymer chain structural factors, like chain microstructure, comonomer content in copolymer, dyad sequence distribution, molecular weight (MW) and molecular weight distribution (MWD), etc. have a great influence on the properties and applications of polymer materials. In this paper, chain structural factors and thermal behaviors of novel trans-1,4-poly (isoprene-co-butadiene) copolymers (TBIR-15, TBIR-20, TBIR-40) with various comonomer contents synthesized by TiCl4/MgCl2-Al (i-Bu)3 catalyst system were studied by 13C-NMR, GPC, DSC and WAXD. Eight fractions for each TBIR sample were obtained through isothermal crystallization fractionation of TBIR in dilute solution. It is proved that all fractions in the TBIR samples were high trans-1,4-configuration copolymers (>89 mol%). The TBIR copolymers were mainly composed by G fractions (44∼76 wt%), which cannot be crystallized from the dilute solutions at −20 °C. The G fractions of the TBIR-15 and TBIR-20 were multi-block copolymers composed by short trans-1,4-polyisoprene (TPI) blocks with the number-average sequence length of isoprene units (nIp)∼6. The G fraction of TBIR-40 was random copolymer with the melting temperature (Tm) as low as −3.4 °C and the crystallinity (Xc) as low as 4.4%. Fractions D and E in TBIR-15 and TBIR-20 were multi-block copolymers with long TPI blocks (nIp = 6∼24) and the above two fractions show decreased Tm (29∼38 °C) from imperfect TPI crystals. A special fraction A in TBIR-40 was random copolymer containing a few TPI and trans-1,4-polybutadiene (TPB) blocks, and both TPI and TPB blocks had the ability to crystallize. The Mw for each fraction was in the range of 2–6 × 105 and Mw/Mn was in the range of 2–6. Based on the analysis, the possible chain sequence distribution model for each fraction was proposed. It was expected that this research would provide a further understanding about the TBIR copolymer chain structures and inspire the copolymer synthesis with ideal structure and composition as high performance rubber material.Based on the different crystallizability of polymer chain with different chain structures, poly (isoprene-co-butadiene) (TBIR) copolymers were fractionated into eight fractions by isothermal crystallization fractionation. The TBIR-15 is mainly composed by various multi-block copolymers with different length TPI blocks (nIp = 6∼24). The TBIR-40 is mainly composed by random copolymers, among which 69.7 wt% are elastomers, 17.1 wt% consist a few TPI and TPB blocks that both showing weak crystalline behavior.

The rheological properties of polybutene-1 with different molecular weight (Mw) and polydispersity index (PDI) were studied by means of rubber-processing analyzer (RPA). The studies included strain sweeps, frequency sweeps, temperature sweeps, and stress relaxation tests after a sudden shear displacement. It is observed that the linear viscoelastic regions are basically identical for all the samples with different molecular structure and become smaller slightly with increasing frequency. The melts with larger Mw and/or PDI present higher viscoelasticity moduli, melts viscosity, relaxation modulus, and better temperature stability, but lower loss factor and critical shear rate. Furthermore, it is found that crossover frequency decreases with increasing Mw and crossover modulus increases with decreasing PDI. In addition, stress relaxation followed by substantial stress growth is observed for the PB-1 melt with larger Mw in the stress relaxation measurement.

Trans-polydiene rubber family as high-performance tire stock possessed excellent dynamic properties, including excellent anti fatigue, low rolling resistance, low heat buildup, good green strength, and low abrasion loss. Here, Reactor Granule Technology (RGT) was introduced into the field of synthetic rubber for the first time to produce trans-1.4-polyisoprene/trans-1,4-poly(butadiene-co-isoprene) rubber alloy, which showed significant improvement in rubber synthetic technologies and great development in abundance of trans-rubber family. A series of trans-polyisoprene alloys with excellent spherical morphology were successfully synthesized by using sequential multistage polymerization. The alloy was fractionated into four fractions by temperature-gradient fractionation, and the fractionation was analyzed by 1H NMR, 13C NMR, DSC and WAXD.

Diphenyl (4-hydroxyphenyl) hexadecyl phosphonium bromide (POH) -modified montmorillonite (POHMMT) was used to prepare a novel TiCl4/MgCl2/POHMMT compound catalyst and exfoliated iPP/POHMMT nanocomposites were prepared by the in situ intercalative polymerization of propylene with the TiCl4/MgCl2/POHMMT compound catalyst. The POH surfactants don’t change the catalytic characteristic of the Z-N catalyst and the obtained PP presents high isotacticity, normal molecular weight and molecular weight distribution. The WAXD, SAXS and TEM results demonstrate the highly exfoliated iPP/POHMMT nanocomposites were produced by the in situ polymerization with this novel catalyst, while the intercalated iPP/Na+MMT nanocomposites were produced with the TiCl4/MgCl2/Na+MMT compound catalyst. Through this approach, in situ propylene polymerization can actually take place between the silicate layers and lead not only to PP with high isotacticity and molecular weight, but also to highly exfoliated PP nanocomposites.

Selectively epoxidized trans-1,4-polyisoprene (SETPI) and randomly epoxidized trans-1,4-polyisoprene (RETPI) were fabricated successfully through modified surface water-phase suspension epoxidation and solution random epoxidation, respectively. The effects of fabricated method and epoxy degree of ETPI on the glass transition temperature (Tg), dynamic mechanical properties and phase separation phenomenon of the as-fabricated polymer have been investigated by different scanning calorimetry, dynamic mechanical analyzer and phase contrast microscope. The double bonds and epoxy groups sequence structure distribution of different ETPI have been observed and analyzed by 13C-NMR. There is a great deal of difference in the microstructure and sequence distribution of epoxy group in ETPI with different synthesis methods and epoxy degree. The results show that distribution of epoxy group in SETPI is nonuniform which brings about the phase separation.

The effect of molecular weight on the polymorphic transformation of isotactic poly(1-butene)(iPB) under room temperature had been investigated by fourier transform infrared spectroscopy(FT-IR). The phase transformation time, phase transformation rate and phase transformation time difference between phase I and phase II at a given transformation degree were used to analysis the phase transformation kinetics of iPB aging at room temperature. The results show that the reduction of phase II can occur quickly at room temperature and seem less dependent on the molecular weight. However, the molecular weight has great effect on the formation of phase I. When the phase transformation degree for phase I reach 90%, a distinct transformation time difference can be observed. In order to clearly explain the difference in the reduction of phase II and the growth of phase I, a phase transformation model from the chain conformation level for iPB with different molecular weight have been drawn. DSC analysis was used to support the proposed model.

Electrospun nanofibrous membrane is an approved drug carrier. However, the radionuclide carrier used an electrospun membrane is rare. In this study, Poly(lactide-co-glycolide)(PLGA) nanofibrous nonwovens were prepared through electrospinning technology, and then surface modification of the nonwoven was performed to stably conjugate the radioisotope with the fibrous membrane. A novel PLGA nanofibrous nonwoven conjugated with radioactive yttrium 90Y for tumor internal radiotherapy was prepared for the first time. Evaluation of the stability of the radioisotope indicated that the leakage of 90Y from the PLGA membranes can be neglected after 24 h incubation in saline. The retention of 90Y on the PLGA membrane was 75% when five half lives of 90Y expired and the vast majority of radioactive decay had occurred. This labeled nanofibrous membrane function as a novel radio-medical appliance with excellent surface hydrophilic and mechanical properties that can be directly implanted into the lesions not only to locally kill the cancerous cells but also to play the anti-adhesion role at where surgical procedures have been made to remove the tumor tissue.