Cationic polymerization of 5-methylene-2norbornene, 5-ethylidene-2-norbornene, 5-vinyl-2-norbornene, dicyclopentadiene, and norbornadiene-2,5 in the presence of boranes was systematically studied. It was found that B(C 6 F 5 ) 3 in combination with caprylic acid, 1-phenylethanol or water was a highly active catalyst for the polymerization of 5-alkylidene-2norbornenes. The corresponding cationic polymers were obtained with up to yields 95% and with high molecular weights (M w ≤ 430 000). The activity of 5-alkylidene-2-norbornenes in the polymerization using B(C 6 F 5 ) 3 containing systems was the highest among the other monomers (5-vinyl-2-nobornene, dicyclopentadiene, and norbornadiene-2,5). BF 3 •O(C 2 H 5 ) 2 based catalysts turned out to be not so active for cationic polymerization of monomers compared with the systems containing B(C 6 F 5 ) 3 . They produced polymers predominantly containing the addition (vinyl) units instead of isomerization units. The structure of the polymer main chain units depended on the nature of the monomers: in the case of norbornadiene-2,5, 5-methylene-2-norbornene, and 5-ethylidene-2-norbornene the transannular polymerization proceeded, while dicyclopentadiene and 5-vinyl-2-norbornene formed the addition type polymers under the studied conditions.
The influence of crosslinking process on the resulting structural properties of phthalonitrile matrices is studied through theoretical and experimental investigations. Multiscale procedure for generating fully atomistic phthalonitrile networks with simulation of radical polymerization reactions and specific reactions of triazine formation at the mesoscale level is presented and applied to the case of phthalonitrile resin based on low-melting monomer bis(3-(3,4-dicyanophenoxy)phenyl)phenyl phosphate. The structural properties of the generated networks of various conversions and with various amount of triazine are analyzed using the dissipative particle dynamics and atomistic molecular dynamics. Triazine-containing networks are much sparser in comparison with triazine-free ones in terms of simple cycle size. The values of density, coefficients of linear thermal expansion and glass transition temperatures (T g s) agree with obtained experimental data, and are very similar for different crosslinking mechanisms. The dependence of T g on conversion correlates well with the sol-gel transition in network structure.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.