Dual roles of alkyl alcohols as syndiotactic‐specificity inducers and accelerators in the radical polymerization of N‐isopropylacrylamide and some properties of syndiotactic poly(N‐isopropylacrylamide)

Abstract

The effects of simple alkyl alcohols on the radical polymerization of N‐isopropylacrylamide in toluene at low temperatures were investigated. We succeeded in the induction of syndiotactic specificity and the acceleration of polymerization reactions at the same time by adding simple alkyl alcohols such as 3‐methyl‐3‐pentanol (3Me3PenOH) to N‐isopropylacrylamide polymerizations. The dyad syndiotacticity increased with a decrease in the temperature and an increase in the bulkiness of the added alcohol and reached up to 71% at −60 °C in the presence of 3Me3PenOH. With the assistance of NMR analysis, it was revealed that the alcohol compounds played dual roles in this polymerization system; an alcohol compound coordinating to the NH proton induced syndiotactic specificity, and that hydrogen‐bonded to the CO oxygen accelerated the polymerization reaction. The effect of syndiotacticity on the properties of poly(N‐isopropylacrylamide)s was also examined in some detail. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4450–4460, 2006

Prolong and sustain

“…Recently, we have reported stereospecific radical polymerization of N ‐alkylacrylamides by controlling the structures of hydrogen bonding‐assisted complexes of the monomers with added reagents 2–7 . N ‐Alkylacrylamides behaved as hydrogen donors in the presence of Lewis bases such as phosphoric acid derivatives2, 3 or pyridine N ‐oxide derivatives:4 syndiotactic or isotactic polymer was obtained through 1:1 or 2:1 complex formation.…”

Application of multivariate analysis of NMR spectra of poly(N-isopropylacrylamide) to assignment of stereostructures and prediction of tacticity distribution

“…[8][9][10][11] Only the initiating system was changed, from n-Bu 3 B under air to dimethyl 2,2 0 -azobisisobutyrate (supplied by Otsuka Chemical Co., Ltd, Osaka, Japan) under UV irradiation with a UV-LED lamp (375 nm, Optocode Co., Tokyo, Japan) at a distance of ca. 5 cm from the polymerization mixture.…”

“…[5][6][7] Recently, we reported stereospecific radical polymerizations of N-isopropylacrylamide (NIPAAm), at low temperatures, in polar solvents or in non-polar solvents, in the presence of alcohols. [8][9][10][11] The diad tacticities were easily determined from the 1 H NMR signals of the methylene groups in the main chain; the signals showed typical splitting as a result of diad stereostructures, as measured in deuterated dimethyl sulfoxide (DMSO-d 6 ) at 150 1C. [12][13][14][15] However, assignments, in terms of triad stereostructures, had not previously been made.…”

Water sorption on a thin film of stereocontrolled poly(N-ethylacrylamide) and poly(N,N-diethylacrylamide)

“…The weight-average molecular weight (M w ) and polydispersity (M w /M n ) were determined by a size exclusion chromatography. The m content was determined by 1 H NMR [12,16,17]. The cloud point (T c ) of a 1 wt % aqueous solution was estimated by the transmittance curve [12].…”