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Heterophase polymerization of different methacrylates: Effect of alkyl ester group on kinetics and colloidal behavior
Author(s) -
OvandoMedina Víctor M.,
CoronaRivera Miguel A.,
MárquezHerrera Alfredo,
LaraCeniceros Tania E.,
ManríquezGonzález Ricardo,
Peralta René D.
Publication year - 2014
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.40191
Subject(s) - monomer , polymer chemistry , methacrylate , alkyl , chemistry , potassium persulfate , polymerization , differential scanning calorimetry , methyl methacrylate , kinetics , radical polymerization , polymer , organic chemistry , physics , thermodynamics , quantum mechanics
In this article, methyl‐ (MMA), ethyl‐ (EMA), n ‐butyl‐ (BMA), n ‐hexyl (HMA), and 2‐ethyl hexyl (2‐EHMA) methacrylates were homopolymerized in heterophase at 60°C using sodium dodecyl sulfate as surfactant and potassium persulfate as initiator. The effects of monomer content in the reaction mixture (2.5 and 3.5 wt %) and the alkyl ester groups of the methacrylates on the kinetics, average particle diameter (Dp), molar masses, tacticity, and glass transition temperature ( T g ) were studied. The final weight average molecular weights were in the range of 4.53 × 10 5 to 2.78 × 10 6 g/mol with polydispersities between 1.7 and 3.1 for different methacrylates. For 2.5 wt % of monomer concentration, the order of increase in polymerization rate was Rp HMA > Rp BMA > Rp 2‐EHMA > Rp EMA > Rp MMA , whereas for 3.5 wt % of monomer concentration was Rp BMA > Rp HMA > Rp 2‐EHMA > Rp EMA > Rp MMA . This behavior was ascribed to the differences in the water solubility, monomer partitioning between the different phases, and monomers reactivity. The Dp values varied between 42 and 65 nm, increasing according to the hydrophobicity of each monomer. 13 C‐NMR (nuclear magnetic resonance) and differential scanning calorimetry analysis demonstrated that 79–87% of syndiotactic configuration was obtained for the different polymers. The steric effect of the alkyl ester length in the methacrylates contributed directly to promote the syndiotactic configuration. Nevertheless, T g values (between −7 and 120°C) for these polymers decreased when the alkyl ester length increased. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131 , 40191.