The structure of branched polymers of diallyl phthalate

Abstract

AbstractThe complete characterization of a branched polymer involves many factors, the most difficult to assess being the average number of elementary linear portions, or branches, of which the polymer is composed, the degree of polymerization of the branches and the extent of cyclic structure formation. A method of analysis of branched polymers is proposed which should be applicable to polymers of any polyfunctional monomer the unsaturated groups of which are separated by saponifiable links. The method is based on the measurement of degree of polymerization and residual unsaturation of the polymer followed by saponification and determination of degree of polymerization of the resulting polymer, and involves the assumptions that branching in the polymer occurs only by the sharing of a monomer unit by two or more linear portions or branches depending on the number of double bonds in the monomer and also that the average degree of polymerization of the branches remains unchanged by the saponification treatment. Evidence from experiments on the saponification and re‐esterification of poly(allyl acetate) and poly(allyl benzoate) indicates, that, in the case of diallyl esters, the above conditions are satisfied. The technique was therefore applied to three polymers of diallyl phthalate, and in each case the average number of chains and degree of polymerization of the chains were estimated. Evidence of considerable extents of cyclic structure formation was found, each individual branch in the polymers consisting of approximately fourteen diallyl phthalate units, six of which are doubly reacted. It is suggested that the existence of extensive formation of cyclic structures may be partly responsible for the poor correlation of predicted with actual degrees of conversion at gelation in polymerizations involving multifunctional monomers.