High-Glass-Transition-Temperature Hydrocarbon Polymers Produced through Cationic Cyclization of Diene Polymers with Various Microstructures

Abstract

A series of prepolymers were treated with CF3SO3H to cationically cyclize adjacent diene–styrene/diene–diene units into main-chain cyclic units. Diene–diphenylethylene alternating copolymers synthesized using anionic copolymerization were first cyclized completely without intermolecular linking reactions. The cyclization produced much higher T g values (approximately 200 °C) than those of cyclized random diene–styrene copolymers (approximately 130 °C). To eliminate the number of spacer carbons between cyclic repeating units, poly­(1-phenyl-1,3-butadiene) (PPB) was used as a prepolymer in cationic cyclization. The T g increased substantially from 200 to 271 °C as the 3,4-structure content increased from 8% to 80%. The cyclized PPB with high 3,4-structure content is the highest T g hydrocarbon polymer yet reported. All results indicated that the backbone rigidity of the cyclic hydrocarbon polymer can be drastically increased by reducing the number of spacer carbons and increasing carbon sharing between cyclic repeating units.

Extremely High Glass Transition Temperature Hydrocarbon Polymers Prepared through Cationic Cyclization of Highly 3,4‐Regulated Poly(Phenyl‐1,3‐Butadiene)

“…The signal (b) at 5.0–6.5 ppm assigned to the olefinic protons disappeared after cyclization; this implied 100% cyclization (Figure B). The gel permeation chromatography (GPC) curves of P(1‐PB) precursor and its cyclized product show that the curve peak shifted to a lower molecular weight after cyclization because of a reduction in hydrodynamic volume, but the absolute molecular weight did not decrease, as confirmed in our previous work (Figure S3, Supporting Information) . The Tg of cyclized P(1‐PB) can reach 304 °C, corroborating the Tg estimate of 307 °C for a 100% 3,4‐structure through data processed using linear curve fitting (Figure S4, Supporting Information).…”

“…In our previous work, the Tg of cyclized poly(1‐phenyl‐1,3‐butadiene) (P(1‐PB)) increased with the increase in its 3,4‐structure content. The Tg of cyclized P(1‐PB) reached 271 °C when P(1‐PB) exhibited 80% 3,4‐structure content . We thus inferred that the Tg of cyclized P(1‐PB) might be higher than 300 °C if higher 3,4‐selective polymerization of 1‐phenyl‐1,3‐butadiene (1‐PB) could be achieved.…”

“…The Tg of cyclized P(1-PB) reached 271 °C when P(1-PB) exhibited 80% 3,4-structure content. [28] We thus inferred that the Tg of cyclized P(1-PB) might be higher than 300 °C if higher 3,4-selective polymerization of 1-phenyl-1,3-butadiene (1-PB) could be achieved. This is because nearly perfect backbone structure (bridged cyclic configuration) existed simultaneously with bulky pendant groups.We hereby report the synthesis of highly regulated P(1-PB) prepolymers and their cationic cyclization.…”

Synthesis of 1,3-Butadiene and Its 2-Substituted Monomers for Synthetic Rubbers

“…In the typical procedure, acetophenone is first converted into 2-phenylbut-3-en-2-ol in the presence of vinylmagnesium bromide at 0 • C, followed by a dehydration reaction to afford 2-PB in the presence of pyridinium p-toluenesulfonate at 80 • C; THF and toluene are employed as solvents, respectively. Similar to 2-PB, 1-phenyl-1,3-butadiene (1-PB) and 1-(4-methypenyl)-1,3-butadiene (1-MPB) have also gained much attention [120][121][122][123][124][125]. As displayed in Figure 8, vinyl bromide and magnesium are used to prepare the THF solution of vinylmagnesium bromide, followed by the addition of acetophenone (Figure 8a).…”

Dienes and diamondoids: poly(2‐[1‐adamantyl]‐1,3‐butadiene) and random copolymers with isoprene via redox‐emulsion polymerization and their hydrogenation

“…For comparison, poly(n-decyl-1,3-butadiene), with a linear C 10 2-substituent, exhibited a T g at −53 C. Thus, the poly(1-ran-isoprene) system presents itself to entirely new applications. Unsaturation in the poly(1,3)-diene backbone also allows for chemical, enzymatic, and bacterial degradation 22 and presents opportunities for additional modifications including grafting, 23 cyclization, 24 addition of solubility modifiers 25 and blending or covulcanization with other butadiene rubbers. 26 With these possibilities at hand, this report documents a new exploration of poly(1-ran-isoprene).…”