Synthesis, characterization, and Diels–Alder extension of cyclopentadiene telechelic polyisobutylene. III. Silylcyclopentadiene‐telechelic polyisobutylene

Abstract

Telechelic polyisobutylenes with silylcyclopentadiene termini (CpSi‐PIB‐SiCp) were prepared, starting with α,ω‐di(t‐chloro)polyisobutylene and followed by dehydrochlorination, hydrosilylation, and cyclopentadienylation. The prepolymer was characterized and found to have a terminal functionality close to 2.0. Thermal chain extension by Diels–Alder addition of the end groups did not occur, most likely because of fluxional isomerization of the silylcyclopentadiene end groups, confirmed by model studies. Chain coupling of CpSi‐PIB‐SiCp prepolymers with stoichiometric amounts of bismaleimide gave rise to degrees of extension of more than 11.

Quest for a Symmetric [C–F–C]+ Fluoronium Ion in Solution: A Winding Path to Ultimate Success

“…Alarmingly, all attempts at a thermal or Lewis acid catalyzed Diels−Alder reaction using diene 29 and dienophile 28 utterly failed. The diene, it appeared, was very susceptible to rearrangement 17 and decomposition, a finding not surprising in light of the migratory aptitude of silicon groups. At this point, we tried a reaction under high pressure; after a few days at 12 kbar (several times the pressure at the bottom of the Mariana Trench!…”

“…Alarmingly, all attempts at a thermal or Lewis acid catalyzed Diels–Alder reaction using diene 29 and dienophile 28 utterly failed. The diene, it appeared, was very susceptible to rearrangement and decomposition, a finding not surprising in light of the migratory aptitude of silicon groups.…”

Photochemical Cross-Linking of Poly(ethylene terephthalate-co-2,6-anthracenedicarboxylate)

“…Thermally reversible cross-links can also be made by formation of labile covalent bonds. For example, polymers bearing dienes and dienophiles undergo reversible cross-linking reactions, and nitroso-substituted polymers undergo gelation upon formation of nitroso dimers . Other reactions that have been used as mechanisms for cross-linking include anhydride exchange, , complex formation, and disulfide formation…”

Thermally reversible polymer linkages. 3. Covalently crosslinked poly(azlactone)

“…Differential scanning calorimetry (DSC) was performed on a Perkin-Elmer DSC 7 instrument equipped with a N2 purge, a TAC7 data analysis package, and a PE 7500 data system; indium and lead were used as standards. Thermogravimetric analysis (TGA) was obtained using a Perkin-Elmer TGA 7 with N2 purge; the instrument was equipped with TAC7 data analysis and a PE 7500 computer.…”

“…T h i s c o n t e n t i s o n l y l i c e n s e d f o r c o n s u m p t i o n b y A u t h o r i z e d U s e r s a f f i l i a t e i n d i v i d u a l n o t d i r e c t l y a s s o c i a t e d w i t h s c i t e i s p r o h i b i t e d .PERKIN-ELMER7 Series Thermal Analysis Systee 0.0-j-1-r-1-H-1-1-…”