Synthesis of hydrogenated functional polynorbornene (HFPNB) and rheology of HFPNB-based miscible blends with hydrogen bonding

Hydrogenated functional polynorbornene (HFPNB) was first synthesized and then it was used to investigate the rheology of HFPNB-based miscible blends with hydrogen bonding. For the investigation, functional norbornene with carboxylic (–COOH) group was first synthesized and then it was polymerized, via ring-opening metathesis polymerization followed by hydrogenation, to obtain hydrogenated functional polynorbornene (HFPNB), HPNBCOOH. Subsequently, the miscibility of binary blends consisting of (1) HPNBCOOH and polycarbonate (PC) and (2) HPNBCOOH and poly(2-vinylpyridine) (P2VP) was investigated using differential scanning calorimetry (DSC). It has been found that both PC/HPNBCOOH and P2VP/HPNBCOOH blend systems exhibit a broad, single glass transition over the entire range of blend compositions as determined by DSC, indicating that the respective blend systems are miscible, and they were found to form hydrogen bonds as determined by Fourier transform infrared (FTIR) spectroscopy. The dynamic oscillatory shear rheometry has shown that reduced log G′ versus log aTω and log G″ versus log aTω plots with aT being a temperature-dependent shift factor of PC/HPNBCOOH and P2VP/HPNBCOOH blend systems, respectively, are independent of temperature. Further, log G′ versus log G″ plots for both blend systems were also found to be independent of temperature. These observations indicate that an application of time–temperature superposition to the PC/HPNBCOOH and P2VP/HPNBCOOH miscible blend systems with hydrogen bonding is warranted although the difference in component glass transition temperature is as large as 91 °C for PC/HPNBCOOH blends, leading us to conclude that concentration fluctuations and dynamic heterogeneity in the HPBNCOOH-based miscible blend systems might be insignificant.