Effect of β-Cyclodextrin on the Preparation of Poly(methyl methacrylate-co-lauryl methacrylate) Nanoparticles and Their Latex Blending with Natural Rubber

Poly(methyl methacrylate-co-lauryl methacrylate) (PMLMA1) latex with two-layer spheroidal particles and low coagulum was successfully carried out using synthesized surfactants and β-cyclodextrin (β-CD) by suspension polymerization. PMLMA1 was then latex blended with natural rubber (NR) compared to conventional core-shell poly(methyl methacrylate-co-lauryl methacrylate) (PMLMA2) particles. The influences of reaction temperature, mass ratios of surfactants and β-CD, reaction time and initiator loading on conversion, coagulum and molecular weight of PMLMA1 were firstly analyzed. Before contrast analysis of NR/PMLMA1 and NR/PMLMA2, the effect of surfactants and β-CD on NR was discussed. Characterizations of dynamic light scattering, scanning electron microscope (SEM), X-ray diffraction and mechanical strength clearly indicated the good interaction between these stabilizers and NR. According to the analysis of transmission electron microscope, PMLMA1 and PMLMA2 particles were homogeneously distributed on the surface of NR particles, while, SEM measurement showed that surface and cross section of NR/PMLMA1 films were much denser and smoother than correspondingly NR/PMLMA2 blends. The data from tensile strength and elongation at break also indicated that NR/PMLMA1 films were superior to NR/PMLMA2 due to high LMA molar ratio in chemical composition of PMLMA1. Differential scanning calorimetry analysis further demonstrated the strong interfacial adhesion between PMLMA1 phase and NR matrix compared to NR/PMLMA2. Because the preparation was eco-friendly and economical, the novel PMLMA1 latexes are expected to be directly used for the manufacture of dipped films.