Chognot D, Six J L, Leonard M, Bonneaux F, Vigneron C, Dellacherie E
Laboratoire de Chimie Physique Macromoléculaire, UMR CNRS-INPL 7568, Groupe ENSIC, BP 451, 54001 Nancy Cedex, France.
J Colloid Interface Sci. 2003 Dec 15;268(2):441-7. doi: 10.1016/s0021-9797(03)00591-5.
Different water-soluble MPEO-PLA diblock copolymers with various alpha-methoxy-omega-hydroxyl polyethylene (MPEO) and poly(lactic acid) (PLA) block lengths have been synthesized. Their surface-active properties were evidenced by surface tension (water/air) measurements. In each case the surface tension leveled down above a critical polymer concentration, which was attributed to the formation of a dense polymer layer at the liquid-air interface. The applicability of copolymers as emulsion stabilizers in the preparation of PLA nanospheres by an o/w emulsion/evaporation technique was then investigated. Four copolymers presenting sufficient water solubility and good surfactive properties were used to prepare PLA nanospheres with MPEO chains firmly anchored at the particle surface. The effect of polymer concentration in emulsion on particle size and surface coverage was examined. Whatever the copolymer characteristics, it was found that the optimal concentration to obtain a large amount of MPEO at the particle surface was similar (around 2 g/l). The effect of the copolymer composition on MPEO layer characteristics and on colloidal stability was also evaluated. The conformation of MPEO blocks at the PLA particle surface is discussed in relation to the layer thickness and the surface area occupied per molecule.
已合成了具有不同α-甲氧基-ω-羟基聚乙二醇（MPEO）和聚乳酸（PLA）嵌段长度的不同水溶性MPEO-PLA二嵌段共聚物。通过表面张力（水/空气）测量证明了它们的表面活性性质。在每种情况下，表面张力在高于临界聚合物浓度时趋于平稳，这归因于在液-气界面形成了致密的聚合物层。然后研究了这些共聚物作为乳液稳定剂在通过水包油乳液/蒸发技术制备PLA纳米球中的适用性。使用四种具有足够水溶性和良好表面活性性质的共聚物来制备MPEO链牢固锚定在颗粒表面的PLA纳米球。研究了乳液中聚合物浓度对粒径和表面覆盖率的影响。无论共聚物的特性如何，发现要在颗粒表面获得大量MPEO的最佳浓度相似（约2 g/l）。还评估了共聚物组成对MPEO层特性和胶体稳定性的影响。结合层厚度和每个分子占据的表面积讨论了PLA颗粒表面MPEO嵌段的构象。
