(363d) Impact of Chain Microstructure on the Properties and Self-Assembly of Poly(1,3-cyclohexadiene)-Based Diblock Copolymers

While much of what we know about the behavior of polymers comes from studies of flexible chains, chain rigidity is an interesting parameter because of its impact on organization and thermal or mechanical properties. With this in mind, we have studied the self-assembly behaviors of poly(styrene)-b-poly(1,3-cyclohexadiene) diblock copolymers. The rigidity of the PCHD block is set at the nanoscale by tuning the ratio of 1,4/1,2 linkages (chain microstructure) between the cyclohexenyl rings of the backbone during synthesis, affecting thermomechanical properties as well as self-assembly behaviors. The glass transition temperature of PS-b-PCHD diblock copolymers increases as the relative amount of 1,2 linkages in the PCHD block increases due to differences in packing of PCHD chains. Laser light scattering and imaging using electron microscopy and atomic force microscopy reveal how tuning chain microstructure influences the ability of the PS-b-PCHDs to micellize in solution and their organization in thin films. We find an unusual disconnect between the standard definition of persistence length, chain rigidity, and the ability of the chains to self-organize.