表面活性单体2-丙烯酰胺基十四烷磺酸钠的合成及其胶束化行为的研究

以丙烯腈与1-十四烯为主要原料合成了表面活性单体2-丙烯酰胺基十四烷磺酸钠(N aAM C14S),用红外光谱与核磁共振谱确认了N aAM C14S的化学结构,用紫外光谱测定了N aAM C14S在水中的溶解度,用表面张力法(环法)与电导法测定了N aAM C14S在不同温度下的临界胶束浓度(CM C)。结果表明,以丙烯腈与1-十四烯为原料可较顺利地合成N aAM C14S,其K rafft点为22℃,25℃下CM C为9.2×10-4m o l.L-1,且CM C随温度变化很小,25℃的表面张力为48.2mN.m-1,表明N aAM C14S具有较高的表面活性。     

阳离子型表面活性单体(2-丙烯酰胺基)乙基十四烷基二甲基溴化铵的合成及其胶束化行为

以丙烯酸、N,N-二甲基乙二胺及溴代十四烷为主要原料合成了阳离子型表面活性单体(2-丙烯酰胺基)乙基十四烷基二甲基溴化铵(AM C14AB);通过红外光谱与核磁共振谱对AM C14AB的化学结构进行了确认;使用紫外分光光度法测定了N aAM C14S在水中的溶解度,同时采用表面张力测定(环法)与电导测定两种方法测定了AM C14AB在不同温度下的临界胶束浓度(CM C)。实验结果表明,通过酰氯化、酰胺化与季铵化三步反应成功地合成出了丙烯酰胺型阳离子表面活性单体AM C14AB;其K rafft点为21.3℃;25℃下其CM C为6.51×10-4m o.lL-1,对应的表面张力为46.3mN.m-1。     

Polymeric particles prepared with fluorinated surfmer

Fluoro-containing particles have been obtained by miniemulsion polymerization of styrene and n-butyl methacrylate in presence of fluorinated monomer mono-fluoroalkyl maleate (MFM) which acts as a surfmer providing efficient stability to obtained dispersion and functionalization of particle surface with fluoro-groups. Increase of the MFM concentration in reaction mixture reduces the particle size and dispersions with narrower particle size distribution can be obtained. Blends of fluorinated latexes with styrene-butadiene copolymer latex were examined with regard to formation of low free energy surfaces. It has been shown that blends containing MFM-functionalized polymeric particles possess more hydrophobic surfaces then similar latex films, where particles prepared by polymerization of expensive fluorinated monomer have been applied.     

Fluorescence studies of associative behavior of cationic surfactant moieties covalently linked to poly(acrylamide) at the surfactant head or tail

Association properties of hydrophobically modified water-soluble polymers bearing the same (or similar) hydrophobic and charged groups at different relative positions (with respect to the polymer main chain) were compared. Two types of surfactant monomers (surfmers) were synthesized; a cationic surfactant was linked to the p-position of styrene at the surfactant charged head (dimethyldodecyl-4-vinylbenzylammonium chloride (St-QC₁₂)) or at the tail end (13-(4-vinylphenyl)tridecyltrimethylammonium bromide (St-C₁₃Q)). These surfmers were copolymerized with acrylamide (AAm), and the association behavior of the copolymers in water was characterized using different fluorescence techniques. The surfmer contents in the AAm/St-QC₁₂ and AAm/St-C₁₃Q copolymers were fixed to more or less 10 mol%. The surfmer units in the copolymers self-associate to form multipolymer aggregates. An apparent critical micelle concentration (cmc) (i.e. a polymer concentration for the onset of interpolymer association of the surfmer units) estimated from excitation spectra of pyrene probes for AAm/St-QC₁₂ (cmc=2.6×10⁻⁴ g/l) was several times lower than that for AAm/St-C₁₃Q (cmc=1.3×10⁻³ g/l), surfmer units in AAm/St-QC₁₂ showing a stronger tendency for interpolymer association than those in AAm/St-C₁₃Q. The presence of excimer emissions in steady-state fluorescence spectra for the p-substituted styrene residues (phenylene groups) in AAm/St-C₁₃Q indicated that the benzene rings are in close proximity to one another in the polymer aggregates. Steady-state fluorescence spectra and fluorescence quenching by thallium nitrate and 1-nitrohexane indicated that the phenylene groups in AAm/St-C₁₃Q were incorporated in hydrophobic microdomains formed from surfactant hydrocarbon chains, whereas the phenylene groups in AAm/St-QC₁₂ are located near the surface of polymer aggregates in a way that they are sufficiently apart from each other and hence no excimer is formed.     

Use of Polybutylene Terephthalate and Other Engineering Resins for Electrical Connectors: A Cost/ Performance Comparison

Electrical connectors are widely used in products ranging from common electrical household appliances to highly sophisticated electronic equipment. In the simplest terms, a connector is any device used to provide rapid connect/ disconnect service for electrical cable and wire terminations. Styles are so numerous that classification by function might make more sense. Following are some broad classes which give some indications of the various types [11]: