Interfacial activity of polymeric surfactants at the polystyrene carbon dioxide interface

被引:38
作者
Harrison, KL
da Rocha, SRP
Yates, MZ
Johnston, KP [1 ]
Canelas, D
DeSimone, JM
机构
[1] Univ Texas, Dept Chem Engn, Austin, TX 78712 USA
[2] Univ N Carolina, Dept Chem, Venable & Kenan Labs, Chapel Hill, NC 27599 USA
关键词
D O I
10.1021/la980323x
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
The reduction of the interfacial tension at the polystyrene (PS, M-n = 1850)-supercritical CO2 interface is reported for poly(1,1-dihydroperfluorooctyl acrylate) (PFOA) and the block copolymers PS-b-PFOA (3.7K/ 27K) and PS-b-poly(dimethylsiloxane) (PDMS) (2K/16K, 500/10K) at 45 degrees C. PS-b-PDMS (2K/16K) lowers the interfacial tension to 0.5 dyn/cm at 45 degrees C and 238 bar, more than that of any of the other copolymers. On the basis of the dynamics of the lowering of the interfacial tension, the apparent diffusion coefficient of PS-b-PDMS (2K/16K) is 8 x 10(-6) cm(2)/s. The critical micelle concentration of PS-b-PFOA (3.7K/27K) is 9 x 10(-4) wt %. Whereas both the PDMS- and PFOA-based copolymers studied adsorb on the PS surface, PS-b-PFOA is much more effective in stabilizing the PS emulsions. The difference in stabilization is discussed in terms of the surfactant adsorption and the interactions of the anchor and buoy blocks with CO2 and the PS surface.
引用
收藏
页码:6855 / 6863
页数:9
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