Studies on the polymerization of bifunctional monomers. XVI. Cyclopolymerization of o‐divinylbenzene with triphenylmethyl fluoroborate and presumption of the presence of the free growing cation in this system

Abstract

Cyclopolymerization of o‐divinylbenzene was studied by using triphenylmethyl fluoroborate as initiator. The cyclization constant rc (ratio of the rate constant for intramolecular cyclization to that for intermolecular propagation) decreased with increase in polarity of the solvent. This solvent effect as well as the effect of catalysts reported previously could be accounted for by a revised model of the propagating species, where both the counter anion and the o‐vinyl group were coordinated to the carbonium ion. The difference in activation energy between intramolecular cyclization and intermolecular propagation was 6.2 kcal/mole. This value was close to that obtained previously with BF3·OEt2 catalyst but greater than those for anionic and radical polymerizations. When tetraalkylammonium flouroborates were added to the polymerization system in methylene chloride, rc and the molecular weight of the polymer decreased. These results were ascribed to the decrease in the amount of the free propagating cation by the common ion effect.

Syntheses and reactions of ferrocene‐containing polymers. Part IV. Cationic polymerization of 1.1′‐divinylferrocene. Influence of the polymerization condition on the polymer structure

“…The ratio of the frequency factor, A,/A, = 20-70, was much smaller than t h a t forthe cationic cyclopolymerization of o-divinylbenzene (2 -5 .lO*) 6,15) b u t was comparable to those of the anionic and radical polymerizations of the latter monomer (1511) and 507), respectively). Therefore, it seems that the entropic advantage of the intramolecular cyclization is diminished in the cationic polymerization of divinylferrocene, because of rotation of the cyclopentadienyl ring and/or the participation of the iron d-orbital.…”

Stable organic cation salts: Ion pair equilibria and use in cationic polymerisation

“…Probably the most rewarding experiments involving stable carbocation salts have been those using the monomers alkyl vinyl ethers (79)(80)(81), N-vinylcarbazole (82), p-methoxystyrene (21,67), cyclopentadiene (86), o-divinylbenzene (92), and to a lesser extent indene (34).…”

Synthesis of Linear Poly(divinylbenezene) through Proton-Transfer Polyaddition by Oxo Acids

“…Spectrum C for the product in the BF3OEt2-benzene system showed peaks which we attribute to the vinyl and -CH2CH< protons of unit V. Broad absorptions at [3][4][5] ppm distinguishable from the background noise are associated with cyclic structures15,16 formed by intramolecular reactions of pendent vinyl groups. It is concluded that, in this system, addition polymerization of DVB (eq 2) occurred and that about 30% of the pendent vinyl groups were consumed by cross-linking and intramolecular cyclization.…”