Polymerization of allyl esters of unsaturated acids. IX. Controlled ring closure in the radical cyclopolymerization of allyl methacrylate

Abstract

Radical cyclopolymerization of allyl methacrylate (AMA) was investigated in detail, especially under the specified conditions; that is, above the ceiling temperature for a head‐to‐tail propagation (ΔGht ≥ 0) in the polymerization of methacrylate. Thus the structure of the polymer obtained was examined by 1H‐ and 13C‐NMR and infrared (IR) spectroscopy; no existence of unreacted pendant methacrylyl groups was observed, which suggests that, as a cyclopolymerization mechanism of AMA, intermolecular propagation of growing radicals, followed by intramolecular cyclization or intermolecular propagation of the resulting uncyclized methacrylyl radical, occurs exclusively with methacrylyl group. Temperature dependency of cyclization constant Kc was unusual; Kc increased rapidly at elevated temperatures and no linear relationship of ln Kc vs. 1/T was observed. Five‐membered ring formation was favored at an elevated temperature and diluted monomer concentration. These results are discussed thermodynamically in terms of controlled ring closure in cyclopolymerization.

Free-radical crosslinking polymerization of unsymmetrical divinyl compounds, 1 Gelation in the polymerization of allyl methacrylate

“…Now, we need to estimate the values of both r and P wY0 values for calculating the gel point according to Eq. (1): First, the r value of 0.992 was employed by referring to our previous article [4] concerned with the cyclopolymerization of AMA. Second, the primary chain length P wY0 was estimated by the extrapolation of the conversion dependence of weight-average degree of polymerization of the prepolymer determined by light scattering to zero conversion as shown in Fig.…”

“…We have extensively investigated the free-radical polymerization of a variety of symmetrical or unsymmetrical divinyl compounds including diallyl dicarboxylates, [1] dimethacrylates, [2] bis(alkyl fumarate)s, [3] and allyl unsaturated carboxylates [4] in terms of cyclopolymerization and gelation, although our research goal is aimed at the elucidation of the crosslinking reaction mechanism and the control of network formation in order to moleculardesign vinyl-type network polymers with high performance and functionality. Thus, we have recently reviewed the mechanistic discussion of the three-dimensional network formation in the radical polymerization of multivinyl compounds, based on the experimental results obtained mainly in our laboratory.…”

“…[7,8] In this connection, the crosslinking polymerization of allyl methacrylate (AMA) as an unsymmetrical divinyl compound was explored for comparison: Because AMA has two different types of double bonds, i. e., conjugated methacryloyl and unconjugated allyl groups, and the reactivity of the methacryloyl group relative to the allyl group is quite high, the preferential polymerization of methacryloyl group leading to the formation of prepolymer having abundant pendant allyl groups occurs at an early stage of polymerization. [4] With the progress of polymerization, the intermolecular and intramolecular crosslinking reactions occurs graduFull Paper: As an extension of our continuing studies concerned with the free-radical crosslinking polymerization of multivinyl compounds, this article deals with the gelation in the polymerization of allyl methacrylate (AMA) as a typical unsymmetrical divinyl compound containing two types of vinyl groups such as methacryloyl and allyl ones having quite different reactivities. Thus, AMA was polymerized in bulk or in a 1,4-dioxane solution using an azo-initiator at 50 8C in the presence of lauryl mercaptan as chain transfer agent.…”

Oligomerization of Allyl Methacrylate in the Presence of Ethylaluminum Compounds and Isolation of Its Unimer and Dimer

“…The former, strong absorption is attributed to the pendant esters and i5-lactone units, and the latter, weak to y-lactone units. The ylactone content of the cyclized units was estimated to be 5% for A!Et 3 and 0% for AIEt2 Cl at the AI/M molar ratio of 0.5 using the calibration curve presented by Matsumoto et al 3 1 H NMR spectroscopy, cyclization was calculated at 23% for A1Et 3 and 30% for AIEt2Cl at an AI/M molar ratio of 0.5. The addition of A1Et 3 and A!Et 2 Cl to ally] methacrylate caused increase in cyclopolymerization, because the common radical polymerization gave the polymer with cyclization below 10% under similar conditions.…”

“…1 • 2 Cyclopolymerization, though very low under the usual conditions, was highly enhanced with rise in temperature. 3 Ethylaluminum compounds as complexing agents caused great increase the cyclopolymerization of oallylphenyl acrylate and methacrylate. 4 The addition of SnCl 4 to allyl methacrylate induced partial cyclopolymerization, but that of AlEtuClu diminished the yield of polymer with increasing Al/M molar ratio.…”