Zwitterion polymerization of tetrahydro-1-[4-hydroxy-3-(2-hydroxyethoxy)phenyl]thiophenium hydroxide inner salt

Abstract

phenyl]thiophenium hydroxide inner salt was synthesized and then polymerized in bulk and solution over the temperature range 65-140 °C. Bulk polymerization gave linear polymer in 88.3-90.6% yield. The polymer was identified as poly-[oxytetramethylenethio[3-(2-hydroxyethoxy)-l,4-phenylene]] by elemental analysis, IR, and NMR. Sizeexclusion chromatography showed the number-average molecular weight to be in the range 51 300-67 800, depending on the reaction temperature. These are the highest polymer molecular weights ever reported for a zwitterion polymerization. Cyclic oligomers from dimer to hexamer were identified by mass spectroscopy and NMR as minor products. The polymer yields were no higher than 19.4% in solution polymerization unless the TFA salt of the zwitterion was present as an initiator. The yields increased to 62% in the presence of TFA salt. The polymer molecular weights varied from 4420 to 9730, depending on concentration, temperature, and the presence of TFA salt. The predominant polymer end groups were identified by NMR as vinyl and phenol for bulk polymerization and alcohol and phenol for solution polymerization. Our previously proposed mechanism for this type of zwitterion polymerization is discussed in terms of the present study.

Comparative Study of the Silk Fiber Structure and Properties before and after the Tensional Twisting Treatment

“…Fourier transform infrared spectroscopy (FTIR) has been widely used to detect the molecular reaction and conformation transition of silk fibroin; the position and intensity of amide peaks can well indicate the molecular conformation [23][24][25]. The studies on the silk fibroin molecular conformation by Tsukada et al [26][27] showed that silk fibroin was characterized by α-helix absorption peaks around 1655 cm (amide IV).…”

Ring‐Opening Polymerization

“…The polymerization of LXIII, a stable isolable zwitterion, on heating or photolysis involves nucleophilic attack by phenoxide anion on the cyclic sulfonium ring [Hoyle et al, 2001;Odian et al, 1990]. The reaction proceeds as a step polymerization.…”

“…With only a very few exceptions, these polymerizations do not yield polymer molecular weights higher than 1000-3000. Low molecular weights are a consequence of the low concentration of the reacting species, the zwitterions, coupled with facile termination of the zwitterion þ and À centers by reaction with the nucleophilic and electrophilic monomers [Odian and Gunatillake, 1984;Odian et al, 1990]. High molecular weights are obtained in zwitterion polymerizations only when the zwitterion concentrations are high relative to other materials present that can act as terminating agents.…”

Zwitterionic polymerization of 1-[(4-carboxyphenyl)methyl]quinuclidinium hydroxide inner salt

“…Although 0 Sample sealed in a vacuum of 0.1 Torr. 6 Sample sealed in a nitrogen atmosphere.= Sample polymerized with continuous pumping in a vacuum of 0.1 Torr.…”