Heteroarm star polymers contain n arms, of which x arms are comprised of monomer A while n-x arms are comprised of monomer B. These star-shaped polymers are organic materials of entirely new chemical structure. Recent theoretical work predicts they will exhibit unusual segregation and interphase phenomena. Synthetic procedures will be developed for preparation of these new materials with n = 3,4 with precisely defined architectures and for the attachment of special functional groups at the free ends of the B arms. The consequences of interarm interactions in isolated heteroarm stars will be assessed from the rates and equilibrium for macrocyclization, as deduced from excimer emission by molecules in which two arms bear pyrene at their free ends. Discrimination among the various types of interarm interactions that can occur in semidilute solution, melts, and in the solid state will be determined with heteroarm stars selectively labelled for study of excimer emission or the rate of nonradiative singlet-energy transfer. The dynamics of isolated heteroarm stars, as well as their diffusion in concentrated solutions and melts, will be determined using pulsed-gradient spin-echo nuclear magnetic resonance.
