十二烷基硫酸钠在聚苯乙烯胶乳粒子上的吸附  

Adsorption of Sodium Dodecylsulfateon Polystyrene Latex Particles

作　　者：赵剑曦[1] 戴闽光[1] 

机构地区：[1]福州大学化学系,福州350002

出　　处：《Chinese Journal of Chemical Physics》1999年第4期500-506,共7页化学物理学报（英文）

基　　金：大连理工大学染料;表面活性剂精细化工国家重点实验室开放课题基金

摘　　要：光子相关谱和吸附等温线测量表明，SD－离子吸附在聚苯乙烯胶乳粒子表面类似毛发状的高分子链上，并聚集形成串在这些高分子链上的表面胶园，导致高分子链伸展状态改变。吸附等温线是S型，对此分析表明，在25℃且无电解质添加剂时，表面吸附胶团的平均聚集数（n）为2．9，每根高分子链吸附的平均胶团数（m）为5．5．在15℃～35℃升温，n不变但m增加．在32mmol／LNaBr时，n增加而m不变，这表明由于NaBr屏蔽了SD－头基间的静电斥力，引起表面胶团聚集数增加．The adsorption of an anionic surfactant, sodium dodecyl sulfate(SDS), on polystyrene (PS) latex particles has been investigated using dynamic light scattering and adsorption isotherms measurements. The surface of the latex particle studied was found to have a layer of PS chains terminating in negatively-charged sulfate groups. The results showed that SD- adsorbed on these pendant PS chains. Since SD- have the same negative groups in comparison with the end-groups of PS chains and cannot also form hydrogen -bonding with the PS chains, the driving force for the adsorption came mainly from hydrophobic interaction between the alkyl tails of SD- and PS chains. The adsorption isotherm displayed an S-type, which supported the assume of single hydrophobic interaction. Thus initially SD- adsorbed with the hydrocarbon tails in contact with the PS chains, and with the polar groups extending into aqueous solution. On further increasing SDS concentration, SD-aggmpatively adsortal about the sites initially occupied by SD- and finally yielded the surface micelles string along the PS chains at saturaion. The electrostatic repulsion between the charged end-groups of SD- adsorbed along the PS chains caused violent extension of these chains, thus a strong increase in RH. The analysis to the adsorption isotherms showed that, at 25 ℃ and salt-free system. the average aggregation number (n) of the surface micelle is 2.9 and the average micelle number (m) along per polymer chain is 5.5. With increasing temperature over the range of 15℃ ~ 35℃, n does not change but m increases. At 32mmol/L NaBr, n increases whereas m keeps unchanged, which suggested a growth of the adsorbed micelles due to NaBr screening to the electrostatic repulsion between the ionic groups of SDS.

关 键 词：吸附等温线 十二烷基硫酸钠 聚苯乙烯胶乳 

分 类 号：O647.2[理学—物理化学]