Mechanical Behavior of Hydroxyalkyl Methacrylate Polymers and Copolymers

Polymers based on hydroxyalkyl methacrylates [1,2] are becoming more and more important, primarily in medical applications; for instance, in the production of contact lenses. Poly(2-hydroxyethyl methacrylate) (PHEMA) has become by far the most important and also the most used; this polymer, prepared mainly in the form of polymer networks by cross-linking copolymerization with ethylene dimethacrylate, exhibits rubberlike behavior at elevated temperatures (above Tg ≅ 100°C), and also at room temperature if swollen with water or other polar diluents. A number of recent papers have been devoted to the mechanical behavior not only of PHEMA, but also of some of its copolymers and polymers having hydrophilic character and a similar composition.