The polymerization of propylene oxide catalyzed by solid anhydrous KOH is shown to have essentially the same mechanism a s the well-known horriogeneous base-catalyzed polymerizations. The reaction is not surfacecatalyzed and the role of solid KOH is to convert hydroxylic groups almost quantitatively to alkoxide groups. Unsaturated end groups are shown to conie from rearrangement of propylene oxide to allyl alcohol, which initiates new polymer chains. Allyl ethers thus formed are converted t o &-propenyl ethers a t rates dependent upon their molecular weights. A kinetic analysis shows that the proposed reaction sequence accounts for all the characteristics of the polymerization including reaction rates, induction period, average molecular weight, and molecular weight distribution, and the arnount and type of unsaturation in the polymer. (51 C. C Price, lecture delivered a t Sorthwestern University, Dec. 8, 1959 I6J I ) M. Simons and J. J. I'erbanc, J. Polymer Sci , 44, 803 (1!>60) ( 7 ) G. Gee, Chem I n d . fI.ondonj, 678 (19.59).

Copolymers of 2‐sulfoethyl methacrylate, (SEM) were prepared with ethyl methacrylate, ethyl acrylate, vinylidene chloride, and styrene in 1,2‐dimethoxyethane solution with N,N′‐azobisisobutyronitrile as initiator. The monomer reactivity ratios with SEM (M1) were: vinylidene chloride, r1 = 3.6 ± 0.5, r2 = 0.22 ± 0.03; ethyl acrylate, r1 = 3.2 ± 0.6, r2 = 0.30 ± 0.05; ethyl methacrylate, r1 = 2.0 ± 0.4, r2 = 1.0 ± 0.1; styrene, r1 = 0.6 ± 0.2, r2 = 0.37 ± 0.03. The values of the copolymerization parameters calculated from the monomer reactivity ratios were e = +0.6 and Q = 1.4. Comparison of the monomer reactivities indicates that SEM is similar to ethyl methacrylate with regard to copolymerization reactivity in 1,2‐dimethoxyethane solution. The sodium salt of 2‐sulfoethyl methacrylate, SEM⊖Na⊕, was copolymerized with 2‐hydroxyethyl methacrylate (M2) in water solution. Reactivity ratios of r1 = 0.7 ± 0.1 and r2 = 1.6 ± 0.1 were obtained, indicating a lower reactivity of SEM⊖Na⊕ in water as compared to SEM in 1,2‐dimethoxyethane. This decreased reactivity was attributed to greater ionic repulsion between reacting species in the aqueous medium.