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Wang Q.,Shandong Institute of Medical Instruments | Wang C.,Shandong Institute of Medical Instruments | Liu Y.,Shandong Institute of Medical Instruments | Ma L.,Shandong Institute of Medical Instruments
Gaofenzi Cailiao Kexue Yu Gongcheng/Polymeric Materials Science and Engineering | Year: 2012

Poly(L-lactide-co-ε-caprolactone) with various L-lactide/ε-caprolactone(LLA/CL) mole ratios was prepared by ring-opening polymerization using stannous octoate as a catalyst. 1H and 13C-NMR measurements indicate that the copolymer compositions are in agreement with mole ratios of LLA/CL feed. The transesterification causes redistribution of comonomer sequences. The coefficient of the second mode of transesterification ([CLC]) increases with CL content increasing. The copolymer composition affects the average sequence length of L-lactidyl (L LL) and caproyl (L C). Both L LL and L C increase with the feed proportion of their respective monomers. L LL and L C are close to L LL R and L C R calculated from a random distribution of units as CL≤50mol%, and distribution of the copolymer is toward a random sequence. Results of DSC and WAXD show that copolymer crystallinity is closely related to the length of their sequence. The copolymer compositions influence significantly their mechanical properties. As the mole content of CL is less than or equal to 35%, the copolymers exhibit the characteristic of yield deformation and high elasticity of thermoplastic elastomer. Source


Wang Q.,Shandong Institute of Medical Instruments | Liu J.-Y.,Shandong Provincial Hospital | Wang C.-D.,Shandong Institute of Medical Instruments | Ma L.-X.,Shandong Institute of Medical Instruments | And 3 more authors.
IFMBE Proceedings | Year: 2013

PLLA and PGLA sutures for decomposable esophageal stent were investigated in phosphate buffer solution (PBS) (pH=7.4) at 37°C for period of 8 weeks. The in vitro degradation was studied by determining the change of weight loss, pH value, intrinsic viscosity, tensile strength, orientation degree, degree of crystallinity, melting point and surface morphology of the suture samples. The results showed that all properties of PLLA sutures had no obvious changes, however, the properties of PGLA sutures all changed significantly. The pH value, intrinsic viscosity, tensile strength, orientation degree and degree of crystallinity decreased gradually, and the weight loss of PGLA sutures increased with the degradation time. At 6th week, tensile strength of PGLA sutures nearly reached zero, and weight loss approached to 70% at 8th week. The results of DSC showed that melting point of crystalline region of PGLA sutures substantially remained unchanged and melting heat enthalpy increased gradually during in vitro degradation, and the new ordered regions appeared in the amorphous area. The results of SEM showed that surface coating of PGLA sutures spalled initially, and then the sutures occured transverse rupture. Therefore PGLA suture is suitable to prepare decomposable esophageal stent to expand benign esophageal stenosis or stricture, but stent prepared by PLLA suture is not appropriate for treatment of benign esophageal stenosis because it is decomposed for more than 2 months. © 2013 Springer-Verlag. Source


Du X.,Shandong Institute of Medical Instruments | Wang Q.,Shandong Institute of Medical Instruments | Wang C.D.,Shandong Institute of Medical Instruments | Liu Y.,Shandong Institute of Medical Instruments
Advanced Materials Research | Year: 2014

Three biodegradable amphiphilic triblock copolymers: polylactide-poly(ethylene glycol)-polylactide (PLA-PEG-PLA), poly(ε-caprolactone)-poly(ethylene glycol)-poly (ε-caprolactone) (PCL-PEG-PCL) and poly(lactide-glycolide)-poly(ethylene glycol)-poly (lactide-glycolide) (PLGA-PEG-PLGA) were synthesized. Their chemical structures were characterized. In aqueous solution, their self-assembly and degradation were studied by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Spherical micelles were formed in aqueous solution via self-assembly of the amphiphilic triblock copolymers. After degradation, the PLA-PEG-PLA and PCL-PEG-PCL micelles became smaller and the PLGA-PEG-PLGA micelles change to vesicles, which should mainly attribute to their different degradation speed. © (2014) Trans Tech Publications, Switzerland. Source


Wang Q.,Shandong Institute of Medical Instruments | Wang C.,Shandong Institute of Medical Instruments | Du X.,Shandong Institute of Medical Instruments | Liu Y.,Shandong Institute of Medical Instruments | Ma L.,Shandong Institute of Medical Instruments
Journal of Macromolecular Science, Part A: Pure and Applied Chemistry | Year: 2013

A series of biodegradable triblock copolymers PLA-PEG-PLA were synthesized by ring-opening polymerization of D,L-lactide using PEG as initiator. The structures and molecular weights of the triblock copolymers were characterized by1H-NMR and GPC.Their thermal properties were tested by DSC. The thermosensitive gelation behaviors and hydrolytic degradation were investigated. Sol-gel transition was observed with proper LA/EG ratios from 2.23 to 2.57. Besides, the sol-gel transition temperature has a close relation with the concentration and molecular weight of the triblock copolymers. The hydrolytic degradation experiment indicates the copolymers with lower LA/EG ratios degrade faster, and the degradation probably occurred at the PLA block at random. © 2013 Taylor & Francis Group, LLC. Source


Zhu A.,Shandong Institute of Medical Instruments | Wang Q.,Shandong Institute of Medical Instruments | Wang C.,Shandong Institute of Medical Instruments | Liu Y.,Shandong Institute of Medical Instruments | And 2 more authors.
Gaofenzi Cailiao Kexue Yu Gongcheng/Polymeric Materials Science and Engineering | Year: 2013

Poly(L-lactide-co-glycolide-co-ε-caprolactone) (PLLGC) was synthesized by ring-opening polymerization using L-lactide, glycolide and ε-caprolactone. The influences of compression moulding parameters such as preheating temperature, moulding pressure, mould temperature and moulding time on the properties of PLLGC were researched by orthogonal experiment to determine the optimal processing parameters. The influences of the processing parameters on the tensile strength, density, molecular weight and molecular weight distribution of PLLGC after compression moulding were researched by range analysis. The results show that the optimum compression moulding parameters of PLLGC are as follows: preheating temperature of 150°C, moulding pressure of 8 MPa, mold temperature of 100°C, and molding time of 10 min. Source

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