Synthesis And Properties Of The EC And PLLA System Blends

In this paper, a series of copolymer EC-PLLA and EC-PLCL were synthesized by ring opening polymerization method using L-LA, EC and ε-CL as raw materials. Theses copolymers were characterized by infrared spectrum (FTIR), ’H-nuclear magnetic resonance spectrum (1HNMR) and gel permeation chromatography (GPC). PLLA/EC-PLLA/EC and PLCL/EC-PLCL/EC blends with different compositions were prepared by using solution blending method. The microstructure, mechanical properties, shape memory effect and biodegradable properties of the blends were investigated systematically by infrared spectrum(FTIR), differential scanning calorimeters(DSC), X-ray diffraction (XRD) , scanning electronic microscope(SEM), tensile testing, shape memory effect tests and in-vitro degradation tests. The essence and relationship between the composition, microstructure and properties are illuminated. Furthermore, the biocompatibility of the blends was evaluated.The experimental results show that EC-PLLA and EC-PLCL copolymers were successfully synthesized by ring-opening polymerization and the chain structure of these copolymers were verified by FTIR and 1HNMR. The compatibility of the PLLA/EC and PLCL/EC was effectively enhanced by using these copolymers as compatilizer.The PLLA crystal is the crystalline phase of PLLA/EC-PLLA/EC blends. The crystallinity of the blends is affected slightly by the EC-PLLA content. However, the mechanical properties, shape memory effect and biodegradable properties are influenced obviously by the EC-PLLA content. The tensile modulus, tensile strength and the elongation at break initially increase and then decrease with the increase of EC-PLLA content. The shape retention ratio, shape recovery ratio and recovery stress are also show the silimar trend. When the EC-PLLA content is 2.5wt%, the PLLA/EC-PLLA/EC blend possesses the optimal shape memory properties. The degradation rate of PLLA/EC-PLLA blends increases with the increase of the PLAL content.The PLLA crystal is the crystalline phase of PLCL/EC-PLCL/EC blends and the crystallinity of the blends decreases with the increase of EC content. The EC content has apparently affect on the mechanical properties. The tensile modulus, tensile strength and the elongation at break increase initially and then decrease with the increase of EC content. When EC content is 5wt%, the PLCL/EC-PLCL/EC blend possesses the optimal mechanical properties. PLCL/EC-PLCL/EC blends have good shape memory effects. With EC content increasing, the shape rentention ratio increase gradually. However, the shape recovery ratio and recovery stress increase initially and then decrease with the increase of the EC content.When EC content is 5wt%, the PLCL/EC-PLCL/EC blend possesses the optimal shape memory properties. The degradation rate of PLCL/EC-PLCL/EC blends is higher than that of PLCL. With the increase of EC content, the degradation rate of the blends increases.The results of cell cytotoxicity show that the PLLA/EC-PLLA/EC and PLCL/EC-PLCL/EC blends possess excellent biocompatibility, which is superior to that of PLLA and PLCL.