The Influence of Monomers upon Microemulsions with Short Chain Cosurfactant

Abstract

Several monomers (i.e., acrylonitrile (ACN), ethyl acrylate (EtA), acrylate of 2 ethylhexyl (EHA), butyl acrylate (BuA), vinyl acetate (VAc), methyl methacrylate (MMA) and styrene (St)) were investigated in order to study their capacities to form microemulsions. The surfactant was nonyl phenol ethoxylate with 25 moles ethylene oxide and ethanol was used as the cosurfactant. The phase diagrams prove that the capacity for microemulsion formation varies in the following sequence:Conductometric and refractometric studies allowed us to evidence the formation of microemulsions with WaO, bicontinuous or OaW structure. Fluorescence studies give interesting informations on the stabilization capacity of the monomers dispersed by interaction with hydrophobic chain of the cosurfactant. H-NMR studies suggest that the monomers in microemulsions lie in regions with various polarities as function of their chemical nature. In polymerization initiated with benzoyl peroxide the minimum conversions were obtained in zones of composition where the initial microemulsions possess a bicontinuous microstructure. The reactions of degradative transfer of the increasing macroradicals account for these conversion modi®cations. For initiation with ammonium persulphate, its rate of decomposition depends on its ability to displace the proton bonded to the substituted vinylic carbon of the monomer. The productivity of this initiator varies within the sequence MMAThe consumption of the initiator, as induced by the monomer, depends on its chemical nature and on the solubilization site of the microemulsions. 231

Effects of Additives upon Percolation Temperature in AOT-Based Microemulsions

“…The structure and properties of microemulsions can be modified by means of system variations (such as temperature, salinity, presence of unsaturations, etc.) in which the microemulsion is located [11,[44][45][46][47][48][49][50][51][52][53][54][55][56][57]. First, the increase of a physical property such as temperature produces noticeable changes in the microemulsion due to the fact that an increase of the carbon chain mobility is generated, originating a decrease of its efficient length and therefore producing an enhancement of the packing ratio.…”

Filmogen organic–inorganic hybrids obtained by sol–gel in the presence of cationic polymer

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] For filmogen 18,19 or nonfilmogen hybrids, dispersing nanometric-sized inorganics into polymer matrices, (i) an increase in both thermal and dimensional stabilities, (ii) improved physico-mechanical performances, [2][3][4]7,9 (iii) fire resistance, 9 (iv) decreased water absorption, 3 or (v) gas permeability 7,10 were achieved. Depending on the properties of the end-product, filmogen hybrids can be further used as waveguide materials with either nonlinear 1 or photochromic 11 properties, conducting films 6 membranes, 7,10 contact lenses, 15 and anticorrosive coatings.…”