FTIR STUDY OF HYDROGEN BONDING AND CRYSTALLIZATION BEHAVIOR OF BIODEGRADABLE MULTIBLOCK POLY(ESTER URETHANE) COPOLYMER

摘要

@@Shape-memory polymers (SMPs) are a kind of materials that are able to remember and recover their permanent shapes in certain condition after shape deformation.1,2 Recently SMPs have attracted great attention from researchers because they are able to remember two shapes at different conditions, thus having great potential in applications such as smart fabrics, intelligent medical devices, implants for minimally invasive surgery. Generally SMP consists of two components, cross-linkages (hard segments) that determine the permanent shape, and switching segments (soft segment) fixing the temporary shape at temperatures below the transition temperature (Ttrans) which is either the glass transition or the melting temperature of the switching segments. An important class of thermoplastic shape memory polymers are segmented polyurethanes1,2, which are multi-block copolymers of the type (AB)n composed of alternating soft and hard segments along the molecular chain. The hard segments are based on diisocynates and diols, while the soft segments are polyester glycol blocks. In the transitions and crystallization of segmented polyurethanes hydrogen bonding often plays an important role, and FTIR thermal analysis is commonly used to study the hydrogen bonding and crystallization of polyurethane and their copolymers3,4.