MACROMOLECULAR ARCHITECTURE - NATURE AS A MODEL FOR DEGRADABLE POLYMERS

Nature usually combines polymers with short degradation times with pol ymers having long degradation times in an energy and material optimize d process involving hierarchical systems. Sometimes a natural system o f polymers has evolved to degrade in a month, sometimes in many years. The building blocks of the plant and animal kingdom are biopolymers w hich are either oxidizable or hydrolyzable. In natural composites, com binations of the two are common, e.g., in wood. Current trends in poly mer research and marketing of plastics indicate an increasing demand f or the development of a diversity of degradable polymer products with a predetermined service-life. We identify four main routes to design d egradable polymers. The goal is to tailor-make a material which is mor e susceptible to environmental degradation factors (e.g., hydrolysis, biodegradation, photooxidation). The most convenient route is to use c heap synthetic bulk polymers and add a biodegradable or photooxidizabl e component. A more expensive solution is to change the chemical struc ture by introducing hydrolyzable or oxidizable groups in the repetitiv e chain of a synthetic polymer. The third route to degradable polymers is to use biopolymers or derivatives of these where the bacterial pol yhydroxyalkanoates are perhaps the most studied material of them all. The fourth route is to tailor-make new hydrolyzable structures e.g., p olyesters, polyanhydrides, and polycarbonates.