Interchain ordering structure and main chain conformation analysis of thermal stability in vinyl-addition polynorbornene

• Published in: Polymer (Guilford) 2022-10, Vol.257, p.125260, Article 125260
• Main Authors: Kai, Hideki, Izumi, Atsushi, Hayakawa, Shun, Niemiec, J. Alex, Ebner, Carl, Schofield, Mike, Skilskyj, Doug, Rhodes, Larry F.
• Format: Article
• Language: English
• Subjects: Interchain ordering structure; Thermal stability; Vinyl-addition polynorbornene
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2022.125260

The aggregation structure and formation mechanism during film casting using toluene of vinyl-addition poly(norbornene-co-hexylnorbornene)s (P(NB/HNB)s) synthesized using Ni and Pd catalyst were systematically investigated by wide- and small-angle X-ray scattering and gel permeation chromatography–right-angle laser light scattering–viscometry techniques. The correlation of these data with the glass-transition temperature (Tg) was discussed. The single-chain conformation of P(NB/HNB)s was a flexible, stretched structure with respect to the Gaussian chain in a good solvent, as characterized by an exponent of the Mark–Houwink–Sakurada equation, and P(NB/HNB)s formed thin-rod aggregates with a length of 30 nm in semi-concentrated toluene solution via interchain stacking of the rod-like chains. P(NB/HNB) films cast from toluene solution exhibit interchain ordering structures with distances between 0.9 and 1.7 nm depending on the NB/HNB ratio. These findings show that the interchain ordering is driven by the stacking of the rod-like chains, which resulted in the highly ordered interchain structure in the film. The Tg of the Pd-catalyzed polymer films were 20 °C higher than that of the Ni-catalyzed polymer films depending on the interchain structure. There is a strong correlation between interchain ordering structure and Tg, which shows that the Tg of P(NB/HNB)s is primarily influenced by the van der Waals interaction between main chains. [Display omitted] •Aggregation structure and mechanism of vinyl-addition polynorbornenes was investigated.•The polymers formed thin-rod aggregates in semi-concentrated solution and highly ordered interchain structure in the film.•The interchain ordering was driven by the stacking of the rod-like chains during drying process.•There is a strong correlation between Tg of the film and the interchain ordering structure.