Department of Chemical and Life Science Engineering, Virginia Commonwealth University, 601 West Main Street, Richmond, Virginia 23284-3028, USA.
Langmuir. 2010 Apr 20;26(8):5848-55. doi: 10.1021/la903770s.
A copolyacrylate with semifluorinated and polydimethylsiloxane side chains (D5-3) was used as a surface modifier for a condensation-cured PDMS coating. The decyl fluorous group is represented by "D"; "5" is a 5 kDa silicone, and "3" is the mole ratio of fluorous to silicone side chains. Wetting behavior was assessed by dynamic contact angle (DCA) analysis using isopropanol, which differentiates silicone and fluorous wetting behavior. Interestingly, a maximum in surface oleophobicity was found at low D5-3 concentration (0.4 wt %). Higher concentrations result in decreased oleophobicity, as reflected in decreased contact angles. To understand this unexpected observation, dynamic light scattering (DLS) studies were initiated on a model system consisting of hydroxyl-terminated PDMS (18 kDa) containing varying amounts of D5-3. DLS revealed D5-3 aggregation to be a function of temperature and concentration. A model is proposed by which D5-3 surface concentration is depleted via phase separation favoring D5-3 aggregation at concentrations >0.4 wt %, that is, the cmc. This model suggests increasing aggregate/micelle concentrations at increased D5-3 concentration. Bulk morphologies studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM) support this model by showing increased aggregate concentrations with increased D5-3 > 0.4 wt %.
一种带有半氟化和聚二甲基硅氧烷侧链的共聚丙烯酸酯（D5-3）被用作缩合固化 PDMS 涂层的表面改性剂。癸基全氟基团用“D”表示；“5”是一种 5 kDa 的硅氧烷，“3”是全氟和硅氧烷侧链的摩尔比。使用异丙醇通过动态接触角（DCA）分析评估润湿性，这可以区分硅氧烷和全氟润湿行为。有趣的是，在低 D5-3 浓度（0.4wt%）下发现了最大的表面疏油性。更高的浓度会导致疏油性降低，这反映在接触角的降低上。为了理解这一意外的观察结果，我们在含有不同量 D5-3 的端羟基 PDMS（18 kDa）的模型体系上启动了动态光散射（DLS）研究。DLS 表明，D5-3 聚集是温度和浓度的函数。提出了一个模型，其中 D5-3 的表面浓度通过相分离而耗尽，有利于在浓度>0.4wt%时发生 D5-3 聚集，即 cmc。该模型表明，随着 D5-3 浓度的增加，聚集物/胶束的浓度增加。通过扫描电子显微镜（SEM）和原子力显微镜（AFM）研究的体相形态学通过显示在 D5-3>0.4wt%时聚集物浓度的增加来支持该模型。
