Effect of Isoalkyl Lactates as Pendant Group on Poly(acrylic acid)

Abstract

AbstractEsterification of lactic acid with secondary alcohols such as isopropanol and isobutanol followed by acrylic acid was carried out by azeotropic distillation. Mass, Fourier Transform Infrared,1H-Nuclear Magnetic Resonance and proton decoupled 13C-Nuclear Magnetic Resonance spectroscopic techniques confirmed the formation of isoalkyl lactates and isoalkyl lactate acrylates. Poly(isoalkyl lactate acrylate)s were synthesized by free radical solution polymerization technique and molecular weights of the polymers were determined by gel permeation chromatography. Wide angle X-ray Diffraction studies indicated the polymers were amorphous and their average molecular interchain spacing (<R>) value was calculated from 2θ value of amorphous halo. Moisture absorption and glass transition temperature of the polymers decreased with increase in number of carbon atoms of isoalkyl groups and <R> value. Moisture absorption of the polymers were in the range of 2 to 6% (w/w) depending upon the isoalkyl lactate group, relative humidity and time. The moisture absorption of polymers followed Fikian process. Two-step thermal degradation was observed in nitrogen atmosphere and the thermal stability trend can be explained on the basis of <R> value.Keywords: Isolactatesacrylatesmolecular interchain spacingmoisture absorptionthermal degradation