| Heterocoagulation is the aggregation of mixed particle systems where the colloidalparticles may differ in size, charge or chemical composition. The driving force toaggregation may be electrostatic interaction, hydrogen bonding or interfacial tensionbetween these colloid particles, so it is easy to produce the composition particles withdifferent morphological structure and tailorable properties. Hence, two kinds of nano-sizedlatexes with anionic and cationic charges were respectively prepared by semicontinuousmicroemulsion polymerization, then mixed to heterocoagulate to form the compositeparticles. Especially, the effects of the structure and amount of cationic surfactant werediscussed on the emulsion size, and the heterocoagulation conditions to control themorphology of composite particles the diameter and surface characters of componentparticles.The results showed that styrene (St)-butyl acrylate (BA) copolymer anionic colloidparticles with dispersion stability,56nm, glass transition temperature of67.5℃and Zetapotential of-33.1mV were synthesized using St and BA as co-monomers, sodium dodecylsulfate (SDS) and non-ionic surfactant TX-100(2:1) as co-emulsifiers, potassiumpersulphate (KPS) as initiator, and acrylic acid (AA) as a functional monomer. Similarly,St-BA copolymer cationic colloid nanoparticles with dispersion stability, and different sizeof30~80nm were synthesized using cetyltrimethylammonium (CTAB) or G16-6-16(a Geminiemulsifier) as emulsifier,2,2-azobis(2-methylpropionamidine) dihydrochloride (AIBA) asinitiator. By means of heterocogulation process, the strawberry-like micro-particles withdiameter of1-10μm were prepared through mixing the above anionic and cationicmicro-emulsions. And the heterocogulation process includes two steps, i.e. collision gelationand the following gel breaking, the size and morphology of the composite particles can becontrolled by adjusting string rate, non-ionic surfactant dosage and temperature. |
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