NETWORK CHARACTERISTICS OF HOMOPOLYMER AND SOME COPOLYMERS OF POLY(2-HYDROXYETHYL METHACRYLATE)

Soluble poly(2-hydroxyethyl methacrylate) and copolymers of 2-hydroxye thyl methacrylate with n-butyl acrylate and 2-hydroxypropyl acrylate o f varying compositions were synthesised by solution polymerisation. Th e polymers were characterised by dilute solution viscometry and shear viscosity. Crosslinked membranes were prepared from these polymers by introducing crosslinks in solution state through the reaction with 1,6 -hexamethylene diisocyanate at a number of different crosslinker conce ntrations. The membranes swollen in dimethylformamide and water were c haracterised by performing equilibrium swelling measurements and calcu lating polymer volume fraction, the molecular mass between crosslinks (($) over bar M(c)) and equilibrium water content (EWC) at 25 degrees C. The calculation of ($) over bar M(c) used an expression developed b y Peppas & Lucht for equilibrium swelling. This is a modified equation of the original Flory-Rehner expression, that allows non-Gaussian dis tribution of chain lengths. The variation of ($) over bar M(c), with c rosslinker concentration and copolymer composition is discussed in ter ms of structural and molecular characteristics of these highly crossli nked networks.