SURFACE-ACTIVE PROPERTIES OF POLY(N-ALKYLSUBSTITUTED ACRYLAMIDE)S ANDTHEIR ADSORPTION ONTO POLYSTYRENE LATEX-PARTICLES IN WATER

Surface-active properties of copolymers of N,N-dimethylacrylamide (DMA ) with n-alkylsubstituted acrylamides, namely as n-butylacrylamide (NB A), n-hexylacrylamide (NHA), n-octylacrylamide (NOA), n-dodecylacrylam ide (NDA), and their adsorption onto polystyrene (PS) latex particles were studied at 25 degrees C in water. Surface tension lowering (Delta gamma) at a concentration of 0.1 g dL(-1), where adsorption at air-wa ter interface is close to saturation, increased with the content of N- alkylacrylamide units for respective copolymers containing different N -alkylacrylamide units. The dependence was stronger for copolymers wit h N-alkylacrylamides bearing the higher alkyl group. The amount of ads orption (W-s) onto PS particles at saturation also increased with the content of N-alkylacrylamide units in the copolymers. W-s linearly inc reased with Delta gamma for copolymers with NEA and those with lower c ontents of NHA and NOA which do not form intramolecular hydrophobic mi crodomains, whereas copolymers of NDA and those with higher contents o f NHA and NOA, which form the microdomains, exhibited large W-s but a small increase with Delta gamma. W-s were lower and also slightly incr eased with Delta(g)amma for polymers of DMA, N-acryloylpyrrolidine (AP R) and N-isopropylacrylamide (IPA). It was deduced that the adsorption s of polymers and copolymers used here al air-water and PS particle-wa ter interfaces are mainly governed by their overall hydrophobicity and that of their alkyl groups of n-alkylacrylamide units, respectively.