Semi-continuous emulsion co-polymerisation of methylmethacrylate and butylacrylate using zwitterionic surfactants as emulsifiers: Evidence of coagulative nucleation above the critical micelle concentration

Coagulative Nucleation in the Copolymerization of Methyl Methacrylate-Butyl Acrylate under Monomer-Starved Conditions

Coagulative nucleation in the copolymerization of methyl methacrylate-butyl acrylate (MMA-BA) via semicontinuous emulsion heterophase polymerization (SEHP) under monomer-starved conditions in latexes with high solid content (50.0 wt %) and low concentrations of surfactant is reported. The SEHP technique allows the obtention of latex with high colloidal stability and has potential industrial application in polymer synthesis. High instantaneous conversions (>90%) and a high-ratio polymerization rate/addition rate (R_p/R_a) ≥ 0.9 were obtained at low times until the final copolymerization, which confirmed the starved conditions in the systems at the highest surfactant concentrations. The particle size exhibited a linear size increment at conversions between 0 and 40% induced by homogeneous nucleation, a transition region between 40 and 50%, and non-linear behavior at higher conversions by coagulative nucleation. These three behaviors were also observed in the particle surfactant coverage area (Sc), Z-potential, particle coagulation rate (dN_p/dt) by the Smoluchowski model, final particle size (Dp_z), and number particle (N_p) through the reaction. By means of transmission electron microscopy (TEM) images, the onset of coagulation was observed from 50% of conversion until the end of the reaction. In addition, in both processes of copolymerization, tacticity was displayed (mainly syndiotacticity).

Synthesis of Five and Six-Membered Heterocycles Using Activated Nitriles for Industrial Applications

The aim of this study is a synthesis of new bioactive heterocyclic compounds incorporated fatty chain for use in different industrial applications. Cyanoacetamide derivative (2) was successfully transferred into five and six membered heterocyclic derivatives by the reaction with various chemical reagents. Addition number of moles of propylene oxide to these compounds gave nonionic surface-active agents having a good solubility, biodegradability and hence lowers the toxicity to human beings and becomes environmentally friendly. The antimicrobial and surface activities were investigated that showed the most of them have pronounced activity, which makes them suitable for diverse applications like the manufacturing of drugs, pesticides, emulsifiers, cosmetics, etc.