Unsubstituted vinyl-addition polynorbornene (VAPNB) possesses many outstanding properties, such as high thermal, chemical, and oxidative stabilities, which makes it a promising candidate for engineering and high-performance applications. However, VAPNB’s limited solubility in common organic solvents, brittleness, and narrow service window between its glass-transition temperature (T_g) and decomposition temperature (T_d) limit its processability and overall utility. While studies have shown that the solubility of VAPNB may be dramatically enhanced by the introduction of side-chain moieties, thereby facilitating solvent processing to yield robust films, their overall industrial appeal would be enhanced if they could be melt-processed into various form factors.
Herein, we describe our efforts to develop melt-processable VAPNBs (service window > 100 °C) via monomer design. In this work, a systematic series of VAPNBs with various functional groups were synthesized using a Pd-based vinyl-addition catalyst. This library of materials is used to examine the relationship between molecular structure and thermal properties. The T_g and T_d of homopolymers and copolymers were characterized by multiple techniques, including modulated DSC, DMA, ellipsometry, and TGA. Furthermore, T_g prediction curves were also constructed and compared to experimentally determined values. We found that the resulting (co)polymers possessed sufficiently suppressed T_g’sand consistently high T_dvalues to yield a tailored service window of > 100 °C while maintaining a T_g > 150 °C. Finally, we demonstrated the melt processibility of select VAPNBs by melt extrusion and characterized their mechanical properties via tensile testing.

Holly Stretz

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