Polymerization kinetics and microstructure of waterborne acrylic/alkyd nanocomposites synthesized by miniemulsion

Abstract

Waterborne acrylic‐alkyd nanocomposites are expected to combine the positive properties of alkyd resins and acrylic polymers. In this work, the kinetics of the miniemulsion polymerization used to synthesize these nanocomposites and the effect of the process variables on the polymer architecture and particle morphology was investigated. It was found that resin hydrophobicity and the type of initiator strongly affected the microstructure of these materials. The mechanisms responsible for these effects were discussed. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4871–4885, 2009

Transformation of waterborne hybrid polymer particles into films: Morphology development and modeling

“…synthesized with the hydrophobic resin had an alkyd rich dark core and an acrylic lighter shell, which agrees well with the equilibrium morphology predicted using the interfacial tensions measured for pure polyacrylates MMA/BA/SA/AA (1), alkyd resin SETAL 293 (2) and water (3):  13 = 20 mN/m and  23 = 33 mN/m [38]. The actual value of  12 is unknown, although a low value is expected due to the existence of a large amount of grafted copolymer.…”

“…Usually, the acrylic chains are substantially longer than the alkyd ones, and therefore most of the acrylic chains contain some alkyd grafted (i.e., ADG is high), whereas only a fraction of the alkyd is grafted to the acrylic polymer, namely, the majority of the alkyd is not grafted [38] (i.e., RDG is usually low). RDG can be increased by maintaining the alkyd resin and the acrylic polymer in close vicinity (hydrophobic resins give higher RDG than hydrophilic ones), using initiators that generate radicals active in hydrogen abstraction (e.g., tert-butyl hydroperoxide, TBHP/ascorbic acid, AsAc, which yields oxygen centered radicals and hydrophobic enough to readily enter into the polymer particles) [42], and using monomers of different reactivity with the double bonds of the alkyd resin (e.g., acrylates are more reactive than methacrylates) [31].…”

“…The formulations are summarized in Table 1. The reactions were carried out by batch miniemulsion polymerization following the procedure given elsewhere [38].…”

Particle Nucleation Using Different Initiators in the Miniemulsion Polymerization of Styrene

“…Note that N p increased at the beginning of the polymerization due to the early formation of new polymer particles by secondary nucleation, while it then decreased as a consequence of the later disappearance of non-nucleated droplets. Secondary nucleation is more probable to occur when water-soluble initiators (e.g., KPS) are used, yielding hydrophilic radicals that promote the formation of new particles by homogeneous or micelar nucleation [Lopez et al, 2011;Goikoetxea et al, 2009]. On the other hand, high organic phase viscosities limited the droplet diameter reduction and hence the number of droplets able to be nucleated with radicals coming from the aqueous phase.…”

Kinetics of MMA and VAc Miniemulsion Polymerizations Using Miglyol and Castor Oil as Hydrophobe and Liquid Core

“…In addition, slower kinetics was also shown to occur in miniemulsion copolymerizations of MMA and butyl acrylate in the presence of linoleic acid and sunflower seed oil [18], linseed oil-modified polyurethane [19], or alkyd resin [20] and was attributed to the chain transfer to those components and/or to reactions with the double bonds present in those components, both resulting in radicals with a lower reactivity.…”