The effect of surfactant (sodium dodecyl sulfate) concentration on particle size, molar masses, glass transition, and tacticity of poly(methyl methacrylate) (PMMA) nanoparticles synthesized by semicontinuous heterophase polymerization under monomer-starved condition at constant monomer feeding rate is reported. Starved conditions are confirmed by the low amount of residual monomer throughout the reaction and by the fact that the instantaneous polymerization rate is similar to the feeding rate of monomer. Under these conditions, polymer particles in the nanometer range (20-30 nm) were obtained with narrow size distribution (1.07 < D w /D n < 1.18), depending of surfactant concentration. Final particle size diminishes as the surfactant concentration is increased. Glass transition temperatures and syndiotactic content (54%-59%) of the produced polymers are substantially higher than those reported for commercial and bulkmade PMMA. Molar masses are much lower than those expected from termination by chain transfer to monomer, which is the typical termination mechanism in 0-1 emulsion and microemulsion polymerization of this monomer.

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ABSTRACT:The compatibilizing effect of the ionomer, poly(styrene-co-sodium acrylate) (PSSAc), on immiscible blends of polystyrene (PS)/polyamide 6 (PA6) was studied by mechanical tests and scanning electron microscopy. The PSSAc acts as an effective compatibilizer because both the deformation at break (%) obtained by tensile stress-strain tests and the impact rupture energy are larger in blends containing small amounts of PSSAc. The morphologies of the fractured surfaces produced by tensile stress-strain tests of blends with or without the ionomer confirm that PSSAc increases the interfacial adhesion between PS and PA6 phases.

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Multiwalled carbon nanotubes (MWNTs) were functionalized with four different functional groups and used as nanofillers to reinforce biodegradable polyurethanes (PU), in an effort to explore their effect on the thermal and mechanical properties of the obtained nanocomposites. The PU were synthesized via one step process, by the reaction between a αω‐telechelic polyester diol (obtained by biocatalysis from ε‐caprolactone and diethylene glycol), and hexamethylene diisocyanate. The MWNTs were synthesized via a chemical vapor deposition process using ethanol as a carbon source. Functionalization with (i) hydroxyl and carboxyl groups OH‐COOH; (ii) aliphatic amine: ethylene diamine; (iii) aromatic amine: 4‐amine benzoic acid (4AB); or (iv) aromatic amine and carboxyl acid: 4‐amine benzoic acid, hidroxyl, and carboxyl groups (4AB‐OH‐COOH) were achieved. Nanocomposites were obtained by adding functionalized CNTs during the polymerization reaction between αω‐telechelic diol and the isocyanate. Three different percentages of functionalized CNTs were tried: (a) 0.25; (b) 0.5; or (c) 1%wt. The structural, morphological, and mechanical features of MWNTs/PU nanocomposites were studied by FT‐IR, differential scanning calorimetry, field emission scanning electron microscopy, TGA, wide angle X‐ray diffraction, solid‐state NMR, and mechanical properties. A better interfacial adhesion was observed for nanocomposites containing 0.5% wt of filler, compared to the neat PU. POLYM. COMPOS., 39:E697–E709, 2018. © 2016 Society of Plastics Engineers