Poly . solvent-nonsolvent

Most research into the study of dispersion polymerization involves common vinyl monomers such as styrene, (meth)acrylates, and their copolymers with stabilizers like polyvinylpyrrolidone (PVP) [33-40], poly(acrylic acid) (PAA) [18,41],poly(methacrylicacid) [42],or hydroxypropylcellulose (HPC) [43,44] in polar media (usually alcohols). However, dispersion polymerization is also used widely to prepare functional microspheres in different media [45, 46]. Some recent examples of these preparations include the (co-)polymerization of 2-hydroxyethyl methacrylate (HEMA) [47,48],4-vinylpyridine (4VP) [49], glycidyl methacrylate (GMA) [50-53], acrylamide (AAm) [54, 55], chloro-methylstyrene (CMS) [56, 57], vinylpyrrolidone (VPy) [58], Boc-p-amino-styrene (Boc-AMST) [59],andAT-vinylcarbazole (NVC) [60] (Table 1). Dispersion polymerization is usually carried out in organic liquids such as alcohols and cyclohexane, or mixed solvent-nonsolvents such as 2-butanol-toluene, alcohol-toluene, DMF-toluene, DMF-methanol, and ethanol-DMSO. In addition to conventional PVP, PAA, and PHC as dispersant, poly(vinyl methyl ether) (PVME) [54], partially hydrolyzed poly(vinyl alcohol) (hydrolysis=35%) [61], and poly(2-(dimethylamino)ethyl methacrylate-fo-butyl methacrylate)... 

Poly (S-leucinato-AT, 0) cobalt (III) -u- [3,3 -dithiobis (2,4-pentanedion-ato-0,0 )]).—Initially, 1.7460 g disulfur dichloride (12.93 mmol) in 6 mL dry dichloroethane was added dropwise to 5.0088 g Co(leu)(acac)2 (12.93 mmol) in 20 mL dimethylacetamide (DMAC) with 0.7095 g sodium carbonate (6.69 mmol) as a slurry in the dimethylacetamide solution under argon and with vigorous stirring. The mixture was stirred for 24 - 36 h and then precipitated with diethyl ether. Alternatively, the solvent was removed in vacuo at 45 C. The product was collected on a fritted funnel, washed with water, and dried in vacuo at lOO C yield, 5.5 g 95%. The polymer was fractionated (three times) by a DMAC/acetone or dimethyl sulfoxide/acetone solvent/nonsolvent precipitation to remove low molecular-weight material. 

CA films by using the phase inversion process. These CA films were cast from solvent/nonsolvent solutions to yield size exclusion membranes consisting of a thin permselective outer layer and a more porous sublayer. These membranes permitted the rapid permeation of a 1500-dalton poly (ethylene glycol) ester of ferrocene however the reproducibility of results presents a problem with these CA mem-branes. Christie et demonstrated that thin films of plasticized polyvinylchloride (PVC), normally used for potentiometric ion-selective electrode applications, applied to electrodes over a polycarbonate dialysis membrane offered improved selectivity ratios for the amperometric detection of phenolic compounds and H2O2 in the presence of the common biological interferents, ascorbic acid and uric acid, over those observed at the dialysis membrane alone or at a composite dialysis/membrane. 

Manjkow, J., Papanu, J. S., Soong, D. S., Hess, D. W., et al. (1987). An in situ study of dissolution and swelling behavior of poly(methyl methacrylate) thin-films in solvent/nonsolvent binary-mixtures. Journal of Applied Physics, 62(2), 682-688. 

Membrane structure has been observed to be affected by the choice of solvent. In a study preparing poly(vinylidene fluoride) (PVDF) membranes, eight solvents including V,V-dimethylacetamide (DMAc), A/,V-dimethylformamide (DMF), dimethylsulfoxide, V-methyl-2-pyrrolidone (NMP), hexamethylphosphoramide, tetramethylurea, triethyl phosphate (TEP), and trimethyl phosphate were employed and the resultant membranes were compared [25]. It was found that the membrane porosity and hence the water permeability of the membranes were dependent on the mutual diffusivity of solvent and nonsolvent (water). It was claimed that the formation path in the ternary phase diagram led to entry into the demixing region at a higher polymer concentration when the solvent-nonsolvent diffusivity was... 

Tan JMA, Noh SH, Chowdhury G, Matsuura T. Influence of surface tension of solvent/nonsolvent mixtures in membrane casting solutions on the performance of poly(2,6-dimethyl-l,4-phenylene) oxide membranes for gas separation applications. J. Memb. Sci. 2000 174 225-230... 

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