We have discovered that, using polar solvents in the presence of a proton trap, BClg alone can initiate the polymerization of isobutylene. The polymerization rate increased in the order methyl chloride, methylene chloride, 1,2-dichloroethane. Increasing the BCls concentration increases the rate; however the molecular weights are similar at similar conversions. Change in temperature in the studied range -25 to -60 °C had no effect on the polymerization rate or on the molecular weights. The products are low molecular weight asymmetric telechelic polymers carrying a BC12-head group and a tertiary chloro end group. A new initiation mechanism via haloboration is proposed to explain the apparent livingness of the polymerization and the structure of the polymers.

The succinylation of cornstarch by extrusion processing has been studied. Several different factors affecting the succinylation of starch were investigated including water content, succinic anhydride quantity, catalyst type and quantity, and reaction temperature. The degree of substitution (DS) increases with decreasing water content and increasing succinic anhydride quantity. Higher temperature favors hi-gher DS using sodium bicarbonate as catalyst while the opposite is true using magnesium hydroxide as catalyst. Of the three catalysts used, sodium bicarbonate is best. Aqueous solubility and viscosity of the starch succinates tend to increase with increasing DS. Based on the results of aqueous solution viscosity, some samples appear to be promising as commercial thickening agent.Starch/StZrke 49 (1997) Nr. 3. S. 116-120 0 VCH Verlagsgesellschaft mbH, D-69451 Weinheim, 1997

The polymerization of R-methylstyrene was studied in the absence of a separately added cationogen (i.e., initiator) and in the presence of a proton trap, using boron halides (BX3, X ) Cl, Br, and I). The effect of the monomer and BX3 concentration, solvent polarity, and temperature was examined. The polymerization rates increased with decreasing temperature and with increasing solvent polarity. The molecular weight (Mn) of the products also increased with decreasing temperature; however it was relatively independent of solvent polarity. Under identical conditions the Mn's were highest with BCl3, lower with BBr3, and lowest with BI3. Kinetic experiments support that initiation is by haloboration, but direct proof was only obtained for BI3. For polymers made with BI3 the presence of one boron per chain was confirmed by elemental analysis, while the high Mn's obtained with BCl3 and BBr3 prevented quantitative analysis of head and end groups.

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