The end-linking of functionally-terminated polymer chains will be used to obtain a variety of elastomers of known and controlled structure. This technique will be used to achieve a better molecular understanding of rubberlike elasticity and to obtain materials of unusually attractive mechanical properties. Typical polymers investigated will be polyisobutylene, polyacrylates and methacrylates, with both unimodal and multimodal network chain- length distributions and with known numbers of dangling-chain irregularities. Properties will include stress-strain isotherms, strain-induced crystallization, and birefringence. Some cyclics will be used in trapping measurements in such reactions and in the preparation of "Olympic" networks. Additional studies will include unusual materials (such as some gels useful in the preparation of high-performance materials, liquid-crystalline elastomers, spider-web silk, and polypeptides), and some will employ less-common deformations (biaxial extension, shear, and torsion). Novel reinforcing fillers will be prepared by the hydrolysis, photolysis, or thermolysis of organometallic materials such as silicates, titanates, aluminates, etc. The resulting filled elastomers will be characterized primarily by mechanical property measurements, electron microscopy, and X-ray and neutron- scattering techniques.
