Isophorone diisocyanate was first reacted with bis(3-(1-methoxy-2-hydroxypropoxy) propyl) terminated polysiloxanes (PMTS) to input cyanate groups in polysiloxane chains, followed by reaction of these cyanate-containing polysiloxanes with polypropylene and dimethylol propanic acid to get polysiloxanes modified polyurethane (PSU) prepolymers. Dihydroxyl glyceryl methacrylate (GM) was then used as coupling agent to react with the PSU prepolymers to introduce vinyl groups with objective to conduct graft-polymerization with acrylics in a subsequent step in order to finally get polysiloxane-polyacrylic modified polyurethane (PSU-X-AC) ternary grafting hybrid latexes. Non-grafting polysiloxane-polyacrylic- polyurethane (PSU-AC) ternary hybrid latexes were also prepared under the same experimental conditions without coupling agent GM. Regardless of using GM as the coupling agent, the stability of the ternary hybrid latexes was enhanced in the presence of polyacrylics (PAC). When compared with the ternary non-grafting latexes (PSU-AC) prepared without use of GM, the corresponding ternary PSU-X-AC latexes prepared with GM demonstrated smaller particle size combined with narrower size distribution and they also showed lower surface tension. For the latex films, higher mechanical performance was observed for the grafted PSU-X-AC, and phase separation was not observed except in cases where PMTS of high molecular weight (＞2000) was used. Use of GM, the coupling agent, was effective to improve the mechanical properties and water resistance of the hybrid materials. No significant impacts of PMTS level and of its molecular weight were noted with regard to the particle size, the surface tension and the viscosity of the latexes. However, when it comes to the properties of the PSU-X-AC latex films, upper limits were observed for PMTS level and its molecular weight, which were around 2000 and 10% relative to the polymer in binary PSU latex, respectively. Below these limits, use of PMTS in the ternary latexes contributed to enhancement of mechanical property and of water resistance.

Key words: hydroxyalkyl polysiloxane, acrylics, polyurethane modification, coupling agent, tri-component hybrid latex