The microstructure of polybutadiene produced by anionic initiation in diethyl ether and tetrahydrofuran with counterions Li+, Na+ and K+ was determined by 1H‐ and 13C‐NMR. Ionization suppressing salts were added in tetrahydrofuran to ensure that only the ion‐pair reaction was studied. Results are compared with older published data. In general, the 1,4 content of the polymer increases with increasing counterion size but varies somewhat with solvent with a given counterion. The cis component of the 1,4 structures changes with temperature and counterion. It is suggested that this change reflects the proportion of cis and trans centers that carry the reaction.
SYNOPSISPolysulfone membranes were modified heterogeneously by lithiation, using n -butyllithium and low concentrations of tetrahydrofuran (THF). The effects of various conditions of reactant concentration, temperature, and time were determined quantitatively. The degree of substitution was measured by XPS and FTIR, using the carbonyl absorption band of lithium-activated membranes that had been converted to ones containing acyl fluoride substituents. The optimum conditions for membrane functionalization were 0.2M n-butyllithium in hexane at room temperature. The reaction rate increased substantially in the presence of 2% THF. The surface-lithiated membranes can be derivatized, potentially with a wide variety of functional groups.
The rates of reaction of acid chloride groups with nitrophenol groups were measured with the groups attached to polymer chains. The average degree of substitution was kept low, near to one or less groups per chain. It was found that the interpolymer reaction rates decreased several fold in dilute solution for high polymers compared with the rates in more concentrated solutions or with those for low‐molecular‐weight polymers. The results were compared with the models proposed by Morawetz and the effect was of the predicted magnitude. The results also confirmed Morawetz' prediction that smaller effects could be expected for terminally substituted than for randomly substituted polymers.
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