Search

Poly(methyl acrylate) (PMA) and 1:1 poly(styrene-co-methyl acrylate) (PSMA) were prepared by solution and bulk polymerization, respectively. The copolymer was analyzed with NMR to ascertain its composition and microstructure. The solution properties of unfractionated PMA and fractionated PSMA in ethyl acetate were investigated by light-scattering and viscosity techniques at 35°C. Narrow composition heterogeneity as revealed from the light-scattering measurements in different solvents justified the use of a single solvent for the copolymer characterization. The equations relating the limiting viscosity number to molecular weight, the molecular dimension to molecular weight, etc., were found for homopolymer and copolymers in ethyl acetate at 35°C. In the evaluation of the Flory constant K for the unperturbed state by methods based on Flory-Fox-Schaefgen, Kurata-Stockmayer, and Stockmayer-Fixman expressions, only the first method gave a value for PMA in ethyl acetate, consistent with that obtained in other solvents, whereas similar values of K were obtained by the three methods for PSMA in ethyl acetate. The studies indicate reduced thermodynamic interaction for PSMA-ethyl acetate compared to PMA-ethyl acetate, but increased steric effect in the copolymer compared with the homopolymer.

The pyrolysis of poly(methyl acrylate) has been studied with identification of the major pyrolysis products. The degradation mechanism of Cameron and Kane involving random homolytic scission of the polymer chain followed by a series of intermolecular and intramolecular transfer reactions is extended and confirmed, and it is apparent that a series of saturated and unsaturated oligomers of methyl acrylate are produced.

Poly (methyl acrylate) prepared by radical polymerization of methyl acrylate was saponified partially in acetone-water mixtures (5 : 2 and 100 : 1 by volume), using sodium hydroxide as the catalyst. Saponification in an acetone-water mixture of a 5 : 2 ratio by volume proceeded in a homogeneous state, but the reaction solution of a 100 :1 ratio by volume was in a white-turbid state, in which saponification proceeded in a heterogeneous state. The properties of the monolayers of polymers saponified in different states were studied at the air/water interface by measuring the surface pressure. The limiting areas obtained on distilled water for each polymer saponified in these two systems decreased linearly with an increase in the degree of saponification. However, the monolayers of polymer saponified in a homogeneous system were more stable on sodium chloride solution than those obtained in a heterogeneous system, and gave the limiting areas on solutions above 5% corresponding with the theoretical values calc...

The infrared absorption spectra of polymers and copolymers of methyl acrylate and methyl methacrylate have been measured, and then used as the basis of a spectrophotometric method for the analysis ...

The stereoregularity of poly(methyl acrylate) and poly(methyl acrylate-αd) was determined from the NMR spectra. A method of quantitative determination of stereoregularity of poly(methyl acrylate) proposed in this paper is based on the fact that in the 100 Mc./sec. NMR spectrum the absorption peaks due to methylene protons in syndiotactic configurations overlap absorptions due to only one of two methylene protons in isotactic configurations. The stereostructure of poly(methy1 acrylates) polymerized with anionic catalysts such as Grignard reagents, n-butyllithium, and LiAlH4 is generally richer in isotactic diads than in syndiotactic diads. For example, poly(methyl acrylate) polymerized with phenylmagnesium bromide as catalyst at −20°C. consists of 99% isotactic and 1% syndiotactic diads. In radical polymerization, the isotacticity of poly(methyl acrylate) is independent of polymerization temperature. Poly(methyl acrylates) polymerized with a Ziegler-Natta catalyst consisting of Al(C2H5)2Cl and VCl4 have configurations similar to those polymerized by radical initiators. The stereoregularity of poly(methyl acrylate-α-d) resembled that of poly(methyl acrylate) polymerized under the same conditions.

Nuclear magnetic resonance (NMR) spectroscopy was used to determine the stereoregularity of radically polymerized poly(ethyl acrylates), poly(trimethylsilyl acrylates), and poly(isopropyl acrylate-α,β-d2). The ethyl acrylate polymers consisted of a random configuration having about 50% of isotactic diads, and their stereoregularities were independent of the polymerization temperature (40 to −78°C). Poly(trimethylsilyl acrylates) and poly(isopropyl acrylate-α,β-d2) prepared at low temperatures had a syndiotactic configuration. Syndiotactic poly(methyl acrylate) was derived from syndiotactic poly(trimethylsilyl acrylate). For poly(methyl acrylate), an approximate estimation of the stereoregularity by infrared spectroscopy was proposed.

By copolymerizing methyl acrylate with methyl α-chloroacrylate at various ratios, the resulting poly(methyl acrylate) backbone had reactive chlorine sites. The poly(methyl acrylate-co-methyl α-chloroacrylate) was dehydrochlorinated by amine. After hydrolysis to convert methyl ester to sodium salt of the acid, the unsaturated bonds introduced by dehydrochlorination were oxidized to glycol by potassium permanganate and cleaved by periodic acid. The resulting poly(sodium acrylate) was converted to the free acid by ion exchange and reesterified with diazomethane. Degraded fragments having number-average molecular weights of 5,000–12,000 were obtained at 83% polymer recovery. Based on the original chlorine content, the efficiency of overall degradation was 20–26% and perhaps somewhat higher.

A film balance study of the mixed monolayers with various ratios of poly(methyl acrylate) and its saponified polymer or of the monolayers themselves was carried out on distilled water, and the mixed monolayers were compared with individual monolayers of the saponified polymers. These mixed monolayers expanded more than individual saponified polymers at the same degree of saponification, giving larger limiting areas. Their limiting areas deviated from the linearity between the limiting area and the degree of saponification, in contrast to the fact that the limiting areas of individual monolayers decreased linearly with an increase in the degree of saponification. This fact can be considered to be due to interactions between the side chains of the ploymers.

Benzophenone-sensitized photopolymerization of methyl acrylate was shown to be remarkably enhanced by the addition of small amounts of triethylamine. This was attributed to the efficient formation of an electron-transfer complex between photoactivated benzophenone and ground-state amine. Ketyl and amine free radicals derived from this complex were postulated to be the chain-initiating species. Quantum yield experiments indicated that methyl acrylate itself was also a quencher of the benzophenone triplet state.

The kinetics of copolymerization for the methyl acrylate–methyl methacrylate system was studied by using monomers which contain deuterium as a tracer. The experiments were made on two series of copolymerizations: methyl acrylate–deuteromethyl methacrylate, (CH2C(CH3)COOCH2D), and deuteromethyl acrylate (CH2CHCOOCH2D)–methyl methacrylate copolymerization systems. Mass spectrometric analysis was employed for determining the composition of copolymers. The agreement of the experimental results of the two series was reasonable. The monomer reactivity ratios for the methyl acrylate (M1)–methyl methacrylate (M2) system were determined as r1 = 0.47 ± 0.09 and r2 = 2.3 ± 0.5 at 130°C. These values were compared with those calculated from the Price-Alfrey Q-e scheme.