Coagulation and Surface Adsorbability of Polymer Latices in Aqueous Solution of Cationic Surfactants

Abstract

The coagulation and surface adsorbability of styrene/acrylic acid [P (St/AA)], styrene/methyl methacrylate/methacrylic acid [P (St/MMA/MAA)], styrene/acrylamide [P (St/AAm₅) and P (St/AAm₁₀), subscripts of 5 and 10 representing the acrylamide fraction in total monomer (wt%)] copolymer latices and polystyrene (PS) latex in aqueous solution of alkyl pyridinium bromides (abbr.APB, C_nH_2n+1NC₅H₅Br;n=12 : DPB, n=14 : TPB and n=16 : HPB) and alkyl trimethyl ammonium bromides [abbr.ATAB, C_nH_2n+1N (CH₃) ₃Br;n=12 : DTAB, n=14 : TTAB and n=16 : HTAB] were investigated by method of stopped flow and ζ-potential measurement. The distance t from the Stern layer to the slipping plane in the electrical double layer on the latex surface increased with an increase of hydrophilic property of the latex, that is, PS, P (St/AA), P (St/MMA/MAA), P (St/AAm₅) and P (St/AAm₁₀) in this order. The surfactant adsorption increased with the hydrocarbon chain length of APB in the order DPB, TPB and HPB, and the adsorption of APB exceeded that of ATAB. Surfactant adsorption onto the latices decreased with increasing distance t, i.e., in the order PS, P (St/AA), P (St/MMA/MAA), P (St/AAm⁵) and P (St/AAm₁₀). Surfactant concentration for the minimum stability ratio (log W=0) of latex particles corresponded to that of ζ=O of the latex on the ζ-log C (C : surfactant concentration) curve.