Polymethyl methacrylate: Dilute solution properties by viscosity and light scattering

Abstract

A polymethyl methacrylate polymer, prepared by the emulsion technique, was fractionated three times to obtain essentially homogeneous fractions. The intrinsic viscosities and weight average molecular weights were determined in an ideal solvent at 23°C. and in nonideal solvents at 25°C. The constants K and a in the conventional modified equation [η] = KMa were determined. The intrinsic viscosity in an ideal solvent was found to fit closely over the molecular range studied with the relation [η]θ = KM1/2. Light scattering measurements giving root‐mean‐square distance between ends of a polymer chain were carried out. It was shown that these results support both Kuhn's relation (r̄2)1/2 ≈︁ M0.50 and Flory's relation (r̄2)3/2 = M[η]/2.1 × 1021 in an ideal solvent. In a nonideal solvent only Flory's relation was found to be in agreement with the experimental results. The values of volume expansion factor α3 ratios A2M italicw2/(r̄2)3/2 and A2Mw/[η] in a nonideal solvent and the value of the ratio [η]/M1/2 in an ideal solvent showed that the polymer molecules were expanded beyond their random flight dimensions in a nonideal solvent.

Association phenomena of PMMA in solutions and gels

“…The samples used are characterized by the data presented in Table 1. 23) we calculate an ap- Comparing the results of the solutions 2/1 and l/l with the solutions of the atactic samples we state that both reduced specific viscosities have very high values a t room temperature. I n Fig.…”

The relationship between optical exaltation and polymerizability of olefins. Correlation of exaltation with copolymerization

“…Table 7 shows Walling's values for the relative reactivities of styrene and several substituted styrenes toward the methyl methacrylate radical, the molecular exaltations for these styrenes, and LEM, which represents the molecular exaltations of the substituted styrenes less the molecular exaltation for styrene. The correlation of relative reactivities with the differences existing between the molecular exaltation of methyl methacrylate (50,51,22,52,53) and the molecular exaltations of the styrenes (AEM,') was also quite good; less than satisfactory, however, were the correlations of relative reactivities with the differences existing between the specific exaltations of substituted styrenes and styrene (AEZ,) and with the differences existing between the specific exaltations of the styrenes and methyl methacrylate. Figure 2 is a plot of the logarithms of the relative reactivities of these substituted styrenes against AEM,.…”

Reaction Rate of the Formation of Graft Copolymer by Coupling Reaction

“…The molecular weight of PMMA prepared by the radical polymerization was calculated by using the following equation. 4 [1)]=0.71 X 10- 4 Mw 0 . 73…”