Polyethyl methacrylate. II. Dilute solution properties by viscosity and light scattering

Abstract

A polyethyl methacrylate polymer, prepared by the emulsion technique, was fractionated three times to obtain ten fractions. The intrinsic viscosity‐molecular weight relations were established in an ideal and in a nonideal solvent at 23°C. Light scattering measurements giving polymer dimensions were compared with the viscosity theories advanced by Debye‐Bueche, Kirkwood‐Riseman, and Flory‐Fox. The calculated values of the effective bond length b for polymethyl methacrylate and polyethyl methacrylate show that polymethyl methacrylate chain has greater hindrance to rotation than the polyethyl methacrylate chain. The results are explained by consideration of the free volume occupied by the solvent molecules.

Diffusion and viscosity measurements on macromolecules in solution

“…In the meanwhile, we wish to point out the fact that this method could be extended to osmotic pressure and light scattering measurements, some examples of which are already in the literature. 13 In addition, we wish to call attention to the advantage of making measurements at any temperature, instead of a t a temperature predetermined by the nature of the solvent and the possibility of eliminating uncertainties of values of the constants and simplifying calculations by performing all viscosity measurements in a @-solvent. Also, the swelling coefficient, a, can be determined correctly a t any temperature, by utilizing the ratio between intrinsic viscosities in a solvent and in a corresponding 8-solvent.…”

P. J. Flory

“…It is necessary therefore to consider the bonds pairwise consecutively, and to formulate a set of statistical weights for bond i that take account of the state of bond i-1. These statistical weights are c~nvenient1y presented in the form of an array, or matrix, as follows: (15) where the rows are indexed in the order t, g+, g to the state of bond i-1, and the columns are indexed to the state of bond i in the same order. According to the analysis of the alkane chain conformations presented briefly above, U i takes the form,2~,26,28 (16) for any bond 1 < i < n.…”

“…Owing to the three-fold symmetry of the terminal methyl groups of the alkane chain, rotations about the terminal bonds are inconsequential and hence are ignored. The statistical weight for the specified conformation of the chain is obtained by selecting the appropriate factor for each bond from the array (15) according to the state of this bond and of its predecessor, and taking the product of such factors for all bonds 2 to n-l. In the example above this product is ug+ ug+t u tt utg-ug-g-, etc.…”

The effect of stereochemical structure on the viscoelastic behaviour of poly(ethyl methacrylate)

“…The JA values for T, are practically identical with JeN and increase with increasing temperature. The dependences of vertical factors l 0 g F 3~ on 1/T are linear; the activation energies determined from these dependences (PEMA-1 AH=7,9 kJ, PEMA-2 AH= 13,8 kJ, PEMA-3 AH = 13,3 kJ) characterize the dissociation of physical bonds with temperature3'). The rate of decrease in X with T becomes faster with increasing length of the side chain of samples prepared by radical polymerization.…”