The carboxylic acid groups of poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMAA) were derivatized in the solid state using a procedure resulting in esterification by trifluoroethanol vapour. X-ray photoelectron spectroscopy analyses incidate that stoichiometric reaction with PAA was reached after 10 h. However, PMAA did not attain a yield greater than 60%, an effect rationalized in terms of steric hindrance. It is postulated that steric restraints are imppsed by conformational inflexibility related to the pendant methyl group within isotactic portions of the chain.
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Alexander et al. (1996) studied this question.
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