Studies on mechanical and morphological properties of PLA based polyurethane and PLA-b-P2VP block copolymers

Abstract

Poly(lactic acid) (PLA) has been studied vigorously due to its interesting properties such as biodegradable, biocompatibility and good mechanical strength. However, PLA is very brittle in nature which restricts its potential application. Therefore, enhancement of properties of PLA was studied in Chapter 1. Apart of that, PLA also widely used in the preparation of PLA based block copolymers (BCPs). This is because PLA is etchable using simple method which is by base solution. In Chapter 2, PLA based block copolymers consist of poly(lactic acid)-block-poly(2-vinyl pyridine) (PLA-b-P2VP) and poly(lactic acid)-block- poly(4-vinyl pyridine) (PLA-b-P4VP) were prepared. In Chapter 1, PLA based biodegradable polyurethane was prepared. In this study, preparation and properties studies of fully biodegradable thermoplastic polyurethane (TPU) consisting of PLA and PCL is reported. The TPU have a combination of toughness, flexibility, barrier property and also biodegradability that makes them suitable for packaging materials. Flexible polymer (PCL) is chosen as chain extender for its flexibility and could improve on the mechanical properties of PLA. The synthesized PLA based polyurethane showed high elongation at break and gas barrier properties which is crucial in packaging materials. This high performance of polymer is fully biodegradable and can be used in various applications especially in biodegradable packaging. In Chapter 2, PLA based block copolymers (BCPs) were prepared. Block copolymers (BCPs) offer wide variety of self-assembled structures in terms of nanoscale morphologies where it can be applied in nanomaterials and also for nanofabrications. The BCPs undergo phase separation to give various nanoscale morphologies including lamellae, hexagonally packed cylinder, spherical, and gyroid structures. Apart of that, amphiphilic diblock copolymers can form micelles by self-assembling in selective solvents. The commonly observed morphologies of the micelles include s...