PREAPARATION OF CATIONIC LATEXES OF POLY(STYRENE-CO-BUTYL ACRYLATE) AND THEIR PROPERTIES EVOLUTION IN LATEX DILUTION

Cationic latexes were prepared through emulsion copolymerization of styrene （St） and butyl acrylate （BA） with a cationic surfactant, cetyl trimethyl ammonium bromide （CTAB）. Latex properties, including particle size, size distribution, （ potential, surface tension and monomer conversion, were determined for latexes prepared with different CTAB amounts. Evolution of these properties during emulsion polymerization was followed in order to understand the mechanism of the particles formation. Results showed that both particle size and 6＂ potential were function of polymerization time and latex solids. Parallel emulsion polymerizations with cationic, anionic charged initiator and charge-free initiators were also carried out, the latex properties were determined at different polymerization time. All these results were attentively interpreted based on the mechanisms of emulsion polymerization, surfactant adsorption and latex particle stabilization.

Investigation of Cationic Soapless P(St-co-DMAEMA) Latex and Its Electrostatic Adsorption of Laponite

Cationic poly（styrene-co-N,N-dimethylaminoethyl methacrylate） （P（St-co-DMAEMA）） latexes were prepared in the absence of surfactant by using 2,2＇-azobis （2-methylpropionamidine） dihydrochloride （AIBA） as the initiator. The effects of the AIBA concentration, HC1/DMAEMA molar ratio and DMAEMA amount on the emulsion polymerization and the latex properties were investigated. The particle morphology and size, the zeta potential and the amino distribution of the P（St- co-DMAEMA） latexes were characterized by transmission electron microscope （TEM）, dynamic light scattering （DLS） and conductometric titration, respectively. Results showed that the emulsion polymerization performed smoothly with high monomer conversion and narrow particle size distribution under the optimized conditions with AIBA concentration of1 wt%, HC1/DMAEMA molar ratio of 1.2 and DMAEMA content of 5 wt%. The diameter of the dried latex particles decreased and the density of amino groups on the particle surfaces increased with increasing the DMAEMA content. The zeta potential of the P（St-co-DMAEMA） latexes was pH-dependent and the zero point was around at pH 7.2. A facile method was developed to fabricate P（St-co-DMAEMA）/laponite hybrid nanoparticles via electrostatic adsorption, in which the loading capacity of laponite platelets reached 17.7 wt%, and the resultant hybrid nanoparticles showed good thermal stability.

Effect of cationic monomer on properties of fluorinated acrylate latex

Cationic fluorinated acrylate latex was prepared via semi-continuous emulsion copolymerization of cationic monomer and other monomers. The resultant latex and its film were characterized with dynamic light scattering detector and contact angle meter. Influences of amount of DMDAAC on the properties of resultant latex and its film were investigated in detail. Results show that the particle size of the latex has the minimum value knd the zeta potential of the latex is increased when the amount of DMDAAC is increased. In addition, the particle size of the latex is unimodal distribution when the amount of DMDAAC is not more than 2.5%. However, the particle size of the latex is bimodal distribution when the amount of DMDAAC is more than 2.5%. The contact angle is varied slightly with the increase of amount of DMDAAC when it is not more than 2.5%. Nevertheless, the contact angle is decreased with the increase of the amount of DMDAAC when it is more than 2.5%.