PHYSICAL-PROPERTIES OF 2-ACETOXYETHYL METHACRYLATE AND 2-HYDROXYETHYL METHACRYLATE COPOLYMERS

2-Acetoxyethyl methacrylate (AcEMA) has been synthesized from 2-hydroxyethyl methacrylate (HEMA) and polymers and copolymers of the two monomers have been prepared. The effect of composition on the physical properties of the copolymers has been evaluated by d.s.c. and determination of tensile mechanical properties, both on dry and wet samples, flexural dynamic mechanical properties (d.m.t.a.) on dry samples, and water sorption and desorption kinetics. The addition of the more flexible component (AcEMA) significantly lowers the copolymer glass transition and affects its overall properties. These differences are explained by the d.m.t.a. measurements, with storage and loss moduli strongly depending on the copolymer composition. The mechanical behaviour of the copolymers ranges from glassy to rubbery, as a function of composition, with elastic moduli in the range of 100-2500 MPa for dry copolymers and 35-0.3 MPa for wet copolymers. Similarly, the equilibrium water content is affected by the balance of hydrophobic-hydrophilic monomer content, with a higher amount of water being absorbed in copolymers containing less AcEMA.