Vinyl polymerization with a binary system of p‐chlorobenzenediazonium salt and sodium tetraphenylborate

Abstract

A combined system of sodium tetraphenylborate (STPB) and p-chlorobenzenediazonium tetrafluoroborate (CDF) serves as an effective initiator at low temperatures for acrylate monomers such as methyl methacrylate (MMA), ethyl acrylate, and di-2-ethylhexyl itaconate. The polymerization of MMA with the STPB/CDF system has been kinetically investigated in acetone. The polymerization shows a low overall activation energy of 60.3 kJ/mol. The polymerization rate (R p ) at 40°C is given by R p ϭ k[STPB/CDF] 0.5 [MMA] 1.6 , when the molar ratio of STPB to CDF is kept constant at unity, suggesting that STPB and CDF form a complex with a large stability constant and play an important role in initiation and that MMA participates in the initiation process. From the results of a spin trapping study, p-chlorophenyl and phenyl radicals are presumed to be generated in the polymerization system. A plausible initiation mechanism is proposed on the basis of kinetic and electron spin resonance results. A large solvent effect on the polymerization can be observed. The largest R p value in dimethyl sulfoxide is 11 times the smallest value in N,N-dimethylformamide. The copolymerization of MMA and styrene with the STPB/CDF system gives results somewhat different from those of conventional radical copolymerization.

The synthesis and application of novel benzodithiophene based reactive mesogens with negative wavelength dispersion birefringence

“…Following the work of Buchwald and co-workers, 35 the conversion of the aryl chloride to a phenol group via Pd catalysed hydroxylation worked well. Subsequent alkylation, saponification and alkylation with an acrylate precursor (3-chloropropanoyl chloride) afforded 13, which was converted into the reactive acid chloride (14). The reaction of 14 with diols 8a-j in the presence of triethylamine resulted in the double esterification of the dihydroxy groups with the simultaneous conversion of the 3chloropropionate to reactive acrylate groups in one pot to give the final products 15a-j (Scheme 5).…”

“…10 In addition due to their anisotropic optical properties, polymerised thin films of RMs are also used as optical corrective films for both LC 12 and OLED 13 displays. Films produced in this way offer several advantages in comparison to conventional stretched polymer films, 14 such as micro-patterning by inkjet printing, in-cell film coating processes and reduction in film thickness, in addition to the increased variety of optical films possible. 15 One of the challenges posed in the area of liquid crystal devices and films is that of optical dispersion.…”