We have measured the density of liquid sulfur as a function of temperature near the polymerization temperature. We measure between 424 and 445 K, with a precision in density of 2×10−5 and an accuracy of 5×10−4. We see upward shifts of the density within 3 K of the polymerization temperature of about 8×10−4 with each cycle in temperature; these shifts could be due to the reaction of the sulfur with the quartz cell, or to the persistence of metastable polymeric forms of sulfur. Thus we consider the data from the first heating run to be the best, since the sample was then the purest. Our results differ from those in the literature in that, while we see a change in slope at the transition, we do not see a sharp minimum or a singularity. We compare our data to two models of the sulfur polymerization as a second order phase transition: the mean field model [A. V. Tobolsky and A. Eisenberg, J. Am. Chem. Soc. 81, 780 (1959)] and the n→0 magnet model [S. J. Kennedy and J. C. Wheeler, J. Chem. Phys. 78, 1523 (1983)]. Both models assume that the sulfur forms linear polymers which are in an ideal solution in monomeric sulfur, and that the thermal expansions of monomeric and polymeric sulfur are linear within the temperature range under consideration. For the most physically reasonable choice of thermodynamic parameters for the models, the mean field model describes the data better than does the n→0 model. The n→0 model is superior if the change of specific volume on polymerization is adjusted. One possible explanation is that sulfur belongs in the n=1 universality class, not in the n→0 class.

We have measured the mass density, p, of solutions of living poly(a-methylstyrene) in tetrahydrofuran as a function of temperature, T, near the polymerization temperatures, Tp. We measure with a precision in density of 4 X 10"6; the accuracy is limited by our knowledge of the composition to about 3%. We compare our p(T) data to two models of equilibrium polymerization as a second-order phase transition: the -* 0 magnet model (Kennedy, S.

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We present the experimental determination of the liquid–liquid coexistence curve of living poly-α-methylstyrene (initiated by n-butyllithium) in methylcyclohexane. We measured the coexistence curve by measuring the phase separation temperatures of a set of samples of different mole fractions of the initial monomer, x*m. All the samples had the same ratio, r(=0.008), of the mole fraction of the initiator to the mole fraction of the monomer. We also measured the polymerization line by measuring the temperatures at which increases in viscosity signaled the onset of polymerization. The measured upper critical solution point for this system is at a temperature of 274±1 K and at x*m = 0.18 ± 0.02. At this x*m, the polymerization temperature Tp is 285 K, well above the critical temperature. Tp decreases as x*m decreases, so that the polymerization line meets the coexistence curve at about x*m = 0.12. We compare the predictions of a lattice model which is equivalent to the mean field limit of the dilute n→0 magnet model for constant r to the measured phase diagram and find good qualitative agreement. Better agreement might result if we could solve the model without taking the mean field limit.

The cationic photopolymerization of 3-benzyloxymethyl-3-ethyl-oxetane (MOX104) initiated by triphenylsulfonium hexafluoroantimonate under UV light was conducted. The kinetics were investigated by real-time Fourier transform IR spectroscopy and the mechanical and thermal properties of poly(MOX104) were examined by dynamic mechanical analysis and TGA. To adjust the properties of the polymer, different initiator concentrations and comonomer composition were applied. The results showed that the conversion of MOX104 was improved significantly from 17% to almost 90% by adding a certain amount of 3,4-epoxycyclohexane carboxylate or diglycidyl ether of bisphenol A epoxy resin, while not much effect was observed by adding 1,4-butanediol diglycidyl ether. Moreover, the glass transition temperature, decomposition temperature and Young's modulus of poly(MOX104) were improved by adding different amounts of diglycidyl ether of bisphenol A epoxy resin.