Rouzes C, Durand A, Leonard M, Dellacherie E
Laboratoire de Chimie Physique Macromoléculaire, UMR CNRS-INPL 7568, Groupe ENSIC, BP 451, Nancy Cedex 54001, France.
J Colloid Interface Sci. 2002 Sep 1;253(1):217-23. doi: 10.1006/jcis.2002.8357.
Neutral polymeric surfactants were synthesized by covalent attachment of hydrophobic groups (aromatic rings) onto a polysaccharide backbone (dextran). By changing the conditions of the modification reaction, the number of grafted hydrophobic groups per 100 glucopyranose units (substitution ratio) was varied between 7 and 22. In aqueous solution, these polymers behaved like classical associative polymers as demonstrated by viscometric measurements. The associative behavior was more pronounced when the substitution ratio increased. The surface-active properties of the modified dextrans were evidenced by surface tension (air/water) and interfacial tension (dodecane/water) measurements. In each case the surface or interfacial tension leveled down above a critical polymer concentration, which was attributed to the formation of a dense polymer layer at the liquid-air or liquid-liquid interface. Dodecane-in-water emulsions were prepared using the polymeric surfactants as stabilizers, with oil volume fractions ranging between 5 and 20%. The oil droplet size (measured by dynamic light scattering) was correlated to the amount of polymer in the aqueous phase and to the volume of emulsified oil. The thickness of the adsorbed polymer layer was estimated thanks to zeta potential measurements coupled with size measurements. This thickness increased with the amount of polymer available for adsorption at the interface. The dextran-based surfactants were also applied to emulsion polymerization of styrene and stable polystyrene particles were obtained with a permanent adsorbed dextran layer at their surface. The comparison with the use of an unmodified dextran indicated that the polymeric surfactants were densely packed at the surface of the particles. The colloidal stability of the suspensions of polystyrene particles as well as their protection against protein adsorption (bovine serum albumin, BSA, used as a test protein) were also examined.
通过将疏水基团（芳香环）共价连接到多糖主链（葡聚糖）上，合成了中性聚合物表面活性剂。通过改变改性反应条件，每100个吡喃葡萄糖单元的接枝疏水基团数量（取代率）在7至22之间变化。在水溶液中，这些聚合物表现得像典型的缔合聚合物，粘度测量证明了这一点。当取代率增加时，缔合行为更明显。通过表面张力（空气/水）和界面张力（十二烷/水）测量证明了改性葡聚糖的表面活性性质。在每种情况下，表面或界面张力在临界聚合物浓度以上趋于平稳，这归因于在液 - 气或液 - 液界面形成致密的聚合物层。使用聚合物表面活性剂作为稳定剂制备水包十二烷乳液，油体积分数在5％至20％之间。油滴尺寸（通过动态光散射测量）与水相中聚合物的量和乳化油的体积相关。借助于ζ电位测量和尺寸测量估计了吸附的聚合物层的厚度。该厚度随着可用于在界面处吸附的聚合物的量而增加。基于葡聚糖的表面活性剂也应用于苯乙烯的乳液聚合，并获得了表面具有永久吸附的葡聚糖层的稳定聚苯乙烯颗粒。与使用未改性葡聚糖的比较表明，聚合物表面活性剂在颗粒表面紧密堆积。还研究了聚苯乙烯颗粒悬浮液的胶体稳定性以及它们对蛋白质吸附（牛血清白蛋白，BSA，用作测试蛋白质）的防护作用。
