화학공학소재연구정보센터
Langmuir, Vol.26, No.11, 7717-7724, 2010
Use of Hydrophobically Modified Inulin for the Preparation of Polymethyl Methacrylate/Polybutyl Acrylate Latex Particles Using a Semicontinuous Reactor
The seeded semicontinuous emulsion copolymerization of methyl methacrylate (MMA) and butyl acrylate (BuA) stabilized with a graft polymeric surfactant based on inulin, INUTECSPI, as well as its mixture with sodium lauryl sulfate (SLS) is described. The mixture of SLS and Brij58 (alcohol ethoxylated) and the mixture of SLS and Pluronic P85 (block copolymer PEO-PPO-PEO) are also used as surfactant systems. The addition of methacrylic acid (MAA) or acrylic acid (AA) as comonomers is also studied. Previous results proved this inulin-derivative surfactant, INUTEC SPI, to be very effective on synthesizing latexes using a very low surfactant concentration. The kinetic features of the emulsion polymerization (instantaneous conversion and total conversion) were gravimetrically determined along the reactions. Latex dispersions were characterized by photon correlation spectroscopy (PCS) and transmission electron microscopy (TEM) to obtain the average particle size, the particle size distributions (PSDs) as well as the polydispersity index (PdI). The stability was determined by turbidimetry measurements and expressed in terms of critical coagulation concentration. The results showed that the use of the graft polymeric surfactant allowed obtaining highly stable nanorarticles. at low surfactant concentrations and high solid contents (up to 37 wt %). This is an improvement with respect to previous works, in which a mixture of the graft polymeric surfactant with another surfactant was required to obtain stable nanoparticles with low polydispersity. at high solid content. In the present work, low polydispersity was achieved using INUTEC as the only emulsifier, which was related to the absence of secondary nucleations. When a mixture of INUTEC SPI and SLS is used, a wider PSD is obtained due to secondary nucleations. Replacing INUTEC SPI by other nonionic surfactants such as Brij58 or Pluronic P85 leads to an increase of average particle size and wider PSD.