Studies On Modification Of Elastin

Elastin is the extracellular matrix protein responsible for the resilience of tissues and is a critical biochemical component of vascular tissue. It is an insoluble, hydrophobic and extensively cross-linked protein. However, elastin's function is restricted to elasticity and difficult to be processed into new biomaterials. In this thesis, synthesis and properties of elastin graft copolymer via atom transfer radical polymerization (ATRP) and thio-iniferters were described. Further, a new strategy for the preparation of glutin-functionalized elastin graft copolymer was explored.1. Elastin was modified with 2-bromoisobutyryl bromide to prepare macro-initiator and subsequently atom transfer radical polymerization (ATRP) modified to attach poly (2-hydroxyethyl methacrylate) (PHEMA). These modified elastin were examined using FTIR, XPS, TGA, SEM, ion chromatography and dynamic contact angle test. Results showed that PHEMA had been covalently bound to the elastin. Although SEM examination suggested the surface of ATRP-modified elastin was much smoother than that of unmodified samples, the thermal stability of modified samples was slightly lower than that of unmodified samples, that is to say, the initial temperature of pyrolytic decomposition reduced from 307°C to 265°C and and the maximum weightlessness rate temperature changed from 347°C to 316.76°C. The dynamic contact angle test showed that the modified elastin was hydrophilic compared with the high hydrophobicity of elastin itself and after polymerization for 72 h, the advancing angle of elastin decreased from 130.45°to 29.80°and contact angle hysteresis reduced from 70.42°to 29.80°.2. Elastin was firstly modified by reacting the amino-groups on the elastin with para chloromethylbenzoyl chloride and sodium diethyldithiocarbamate to prepare the macro-iniferters and subsequently modified by UV-induced polymerization to attach poly(2-hyroxyethylmethacrylate) (PHEMA).These modified elastin were examined using FTIR, XPS, TGA, SEM, ion chromatography and dynamic contact angle test. Results showed that PHEMA had been covalently bound to the elastin. Although SEM examination suggested the surface of thio-iniferters-modified elastin was much smoother than that of unmodified samples, the thermal stability of modified samples was slightly lower, that is to say, the initial temperature of thermal decomposition reduced from 307°C to 260.2°C and the maximum weightlessness rate temperature changed from 347°C to 316.3°C. The dynamic contact angle test showed that the modified elastin was hydrophilic compared with the high hydrophobicity of elastin itself and after photopolymerization for 72 h, the advancing angle of elastin decreased from 130.45°to 35.40°and contact angle hysteresis reduced from 70.42°to 35.40°.3. A new strategy for the preparation of glutin-functionalized elastin graft copolymer was explored, which is based on a combination of surface-initiated atom transfer radical polymerization (ATRP) of 2-hydroxyethyl methacrylate on the elastin , p-nitrophenyl chloroformate activation of the surface hydroxyl groups, and subsequent glutin functionalization. These glutin-functionalized elastin graft copolymers were examined using FTIR, XPS and SEM. Results of FTIR and XPS showed that glutin had been covalently bound to the elastin graft copolymer. However, SEM examination suggested that any changes could hardly be seen comparing the surface of glutin-functionalized elastin graft copolymer with that of unfunctionalized samples.