We theoretically predict the thermal conductivity versus temperature dependence of Si and Ge nanowires. Three methods are compared: the traditional Callaway and Holland approaches, and our "real dispersions" approach. Calculations with the former two show large disagreements with experimental data. On the contrary, the real dispersions approach yields good agreement with experiments for Si nanowires between 37 and 115 nm wide, approximately. In all cases, only bulk data are used as inputs for the calculation. Predictions for Ge nanowires of varying diameters are given, enabling future experimental verification.

The Smith-Ewart equation has been modified to describe the kinetics of reversible additionfragmentation transfer (RAFT) (mini)emulsion polymerization. Two types of radicals (propagating and intermediate) are taken into account. The influence of RAFT reactions on the (mini)emulsion polymerization kinetics is investigated using the modified Smith-Ewart theory. In a simplified zero-one case, the average number of propagating radicals per particle can be described by n j RAFT -1 ) n j blank -1 + 2K[RAFT] 0 , where K is the RAFT equilibrium coefficient. It is found that the rate retardation is an intrinsic kinetic property of RAFT (mini)emulsion polymerization. The miniemulsion polymerization of styrene is also carried out with styrene oligomers of 1-phenylethylphenyl dithioacetate (PS-PEPDTA) and 2-cyranoprop-2-yl dithiobenzoate (PS-CPDB) as the RAFT agents. The experimental n j data are well described by the theory. The K values are estimated to be 314 L/mol for PS-CPDB and 22 L/mol for PS-PEPDTA. The fragmentation rate coefficients appear to be on the order of magnitude of 10 4 -10 5 s -1 .

Vegetable oils are very heterogeneous materials with a wide distribution of triacylglycerol structures and double-bond contents. The hydrogenation of epoxidized soybean oil (ESO) produces polyols having a functionality distribution related to that of soybean oil. Therefore, these polyols are convenient substances for studying the impact of structural heterogeneity on network formation and properties. Polyols of hydroxyl numbers ranging from 225 to 82 mg KOH/g and weight-average functionalities ranging from 4.4 to 2.7 were obtained by the variation of the time of hydrogenation of ESO. An analysis of the functionality distribution in polyols shows that gel points with diisocyanates vary from 54 to 76% conversion. The molecular weights of the network chains of polyurethanes prepared from these polyols and diphenyl methane diisocyanate varied from 688 to 1993. Polyols with hydroxyl numbers above 200 mg KOH/g gave glassy polymers, whereas those below that value gave rubbers. The heterogeneity of polyols had a negative effect on the elastic properties only at low crosslinking densities.