Mechanistic aspects of the cationic polymerization of vinylformamide

Abstract

SUMMARY:The electron density distributions of the four possible configurational isomers of the monomer vinylformamide (VFA) and of the cationically propagating species were examined by means of quantum chemical calculations. They show that the electrophilic attack of the propagating chain at the carbonyl oxygen of the VFA monomer is kinetically controlled whereas the attack at the C2C bond of the VFA is thermodynamically controlled. For experimental proving of this theoretical argument, VFA is cationically polymerized in toluene at different reaction temperatures by means of iodine, trifluoromethanesulfonic acid (HOTf), and trimethylsiliyl triflate (TMST) as initiators. Head group functionality and molecular weight distribution (MWD) of the oligo(vinylformamide) (OVFA) were investigated by means of 1 H NMR spectroscopy, matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS), gel permeation chromatography (GPC), and combustion analysis. In all cases, OVFAs with narrow MWD were obtained in moderate yield (5 -50%) in the temperature range from 253 to 313 K. A reaction temperature below 253 K is not suitable for the cationic polymerization of VFA because no oligomeric products are obtained. The properties and chemical constitution of the OVFAs, such as the average molecular weight, yield, and the chain structure are strongly determined by the reaction temperature used. With increasing reaction temperature the head group functionality decreases and the yield of OVFA increases. The correspondence between the results of quantum chemical calculations with those of the experiments is discussed.

A new route to poly(N-isopropylacrylamide) microgels supporting a polyvinylamine corona

“…A series of cationic polymerizations of NVF in toluene was conducted using iodine as an initiator following the work of Spange's group [11]. This procedure produced a mixture of useful iodine-terminated oligomer and inactive methyl-terminated product (see Scheme 2).…”

“…Following the procedure of Madl et al [11], 2.0 ml (0.028 mol) of NVF was added to a test tube that contained a solution of 0.071 g iodine in 25 ml toluene. The tube was sealed with Parafilm and kept in a thermostat water bath.…”

“…Oligo(NVF) (Scheme 2) were prepared by cationic polymerization following the recent work of Madl and coworkers [11]. This procedure gave two major products shown in Scheme 2-the iodine-terminated oligomer and a methyl-terminated oligomer.…”

N-vinylformamide - a new environmentally friendly water-soluble monomer

“…Rozstrzygaj¹ce powinny byae w tym przypadku obliczenia kwantowo-chemiczne. Wyniki w³asne pokrywaj¹ siê ca³kowicie z opublikowanymi danymi [25]. Wartooeci ciep³a tworzenia konformerów zamieszczono w tabeli 2. nologii syntezy rozpuszczalnego w wodzie monomeru -N-winyloformamidu o wielu w³aoeciwooeciach wyraŸnie odmiennych od w³aoeciwooeci stanowi¹cego jego izomer akryloamidu.…”

“…W pe³ni kompatybilne z widmem 13 Próbuj¹c wyt³umaczyae obecnooeae dwóch sygna³ów pochodz¹cych od ka¿dego z trzech obecnych w cz¹steczce NVF atomów wêgla, nale¿y przede wszystkim zwróciae uwagê na silnie sprzê¿on¹ strukturê cz¹steczki NVF, co powoduje, ¿e jest ona p³aska, a ponadto mo¿e wystêpowaae w postaci czterech konformerów (wzór V). Na podstawie otrzymanych wartooeci autorzy [25] przyjêli, ¿e sygna³y w widmach NMR (por. rys.…”