Characterization of novel biodegradable elastomers

• Main Author: Chan, Paul Ng Poh Huat.
• Other Authors: Subramanian Venkatraman
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Engineering::Materials
• Online Access: http://hdl.handle.net/10356/15449
• Institution: Nanyang Technological University

Polymers have been rapidly replacing other materials in many applications, even in the biomedical aspect, e.g. replacing a stainless steel heart stent with a biodegradable polymeric one, hence there is a need to find polymers with better properties. In this report, we will explore a relatively new type of polymers called biodegradable thermoplastic elastomers. They are basically elastomers that do not rely on cross-linking to achieve flexibility and elasticity but are usually made up of two segments, a hard block and a soft block, and are thermoplastics in nature. Two biodegradable polymers, poly (lactic acid) and poly (caprolactone), will be copolymerized together using coordinated anionic ring opening polymerization (CAROP) into diblocks and triblocks and then characterized according to their morphology, i.e. the amount of hard and soft blocks, the block lengths, block arrangement, molecular weight, mechanical properties, etc. From this characterization, we would like to find the optimum concentration of poly (lactic acid) and poly (caprolactone) to be added that can achieve the maximum elongation value. After the polymers have been synthesized, characterization was done mainly using Size Exclusion Chromotography (SEC) to measure apparent molar weight, Instron Microtester to measure mechanical properties like Young’s Modulus and elongation value, and Differential Scanning Calorimetry to measure thermal properties like glass-transition temperature and degree of crystallinity. Analyses done so far have managed to produce an elongation value close to 1450% by a diblock copolymer (PCL-co-PLA)-b-(PLA-co-PCL) 10000 Da-10000 Da, with 10% of LA in PCL and 30% CL in PLA. Several recommendations, like using PGA instead of PLA for the hard block portion and an additional test to measure biodegradation rate of the polymers, have been suggested to improve this project.