Environmentally-Friendly Acrylates-Based Polymer Latices - Advanced Materials for Agriculture, Food and Environmental Safety - page 165

Hidalgo et al. [139] prepared latex with a styrene/BA/amide functional
monomer of varied hydrophilicity through emulsion polymerization. h e
polymerization kinetics, size and morphology of latex particles and the
location of the functional groups in the i nal latexes were studied. It was
shown that increasing the hydrophobicity led to better homogeneity in the
copolymer formed during the polymerization, while the more hydrophilic
functional monomer partly homopolymerized in a separate phase.
Duarte et al. [140] studied the equilibrium solubility of carbon dioxide
in P(MMA-co-EHA-co-EGDMA) by gravimetric method at dif erent tem-
peratures and pressures. h e crosslinked copolymer showed the Fickian
behavior and Fick's dif usion model was applied to determine the amount
of carbon dioxide and the dif usion coei cients.
h e ef ect of crosslinking on intercellular polymer dif usion in P(BMA-
co-BA-co-EGDMA) latex i lms containing 0.1-4 mol% EGDMA as a
crosslinking agent was monitored by l uorescent energy-transfer measure-
ments and by atomic force microscopy in a study by Tamai et al. [141]. h e
polymer dif usion decreased with an increase in the levels of crosslinking.
A i lm was prepared from BMA/ethylene urea (EU) emulsion copoly-
mer by Okubo et al. [142]. h e wet adhesion of the emulsion i lm on an
alkyd resin was signii cantly improved by copolymerization with a small
amount of EU (0.5-1.0 mol%). h e localization of EU and the cleanliness
at the particle surface were also key factors in the improvement of the wet
adhesion of the polymer emulsion i lm.
A reactive monomer, acetoacetoxyethyl methacrylate (AAEM), has long
been recognized for its ability to provide a versatile crosslinking site in
thermoset coatings [143]. An important feature of this crosslinking mono-
mer was reported to be a better crosslinking agent for the epoxy resins
in comparison to aziridine and isocyanates. It has relatively low toxicity,
which makes it attractive for high performance, environmentally-friendly,
non-hazardous coatings. h e AAEM-containing waterborne coatings have
gained such high interest as evidenced by recent patents [144-147] and
literature reports [148, 149]. Noomen [150] synthesized acid-functional
resins based on MMA-BA-AAEM and methacrylic acid in a ratio of
21:37:30:12, by weight using emulsion technique. h e mechanism of drying
and crosslinking of acetoacetoxy functional latexes was also investigated.
h e ef ects of divinyl monomers (AMA and BDA) on the kinetics and
mechanical properties (i.e., Tg, storage modules and molecular weight
between entanglements) of the i lm were studied by Bouvier-Fontes et al.
[55]. h e results showed that the addition of the crosslinkers did not sig-
nii cantly af ect the kinetics. Surprisingly, the most reactive crosslinker,
BDA, produced the least crosslinked latex, while AMA formed a highly