Joncheray Thomas J, Denoncourt Kristina M, Meier Michael A R, Schubert Ulrich S, Duran Randolph S
The George and Josephine Butler Polymer Research Laboratory, Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, FL 32611-7200, USA.
Langmuir. 2007 Feb 27;23(5):2423-9. doi: 10.1021/la062626u. Epub 2007 Jan 23.
The interfacial properties of amphiphilic linear diblock copolymers based on poly(ethylene oxide) and poly(epsilon-caprolactone) (PEO-b-PCL) were studied at the air-water (A/W) interface by surface pressure measurements (isotherms and hysteresis experiments). The resulting Langmuir monolayers were transferred onto mica substrates and the Langmuir-Blodgett (LB) film morphologies were investigated by atomic force microscopy (AFM). All block copolymers had the same PEO segment (Mn = 2670 g/mol) and different PCL chain lengths (Mn = 1270; 2110; 3110 and 4010 g/mol). Isothermal characterization of the block copolymer samples indicated the presence of three distinct phase transitions around 6.5, 10.5, and 13.5 mN/m. The phase transitions at 6.5 and 13.5 mN/m correspond to the dissolution of the PEO segments in the water subphase and crystallization of the PCL blocks above the interface similarly as for the corresponding homopolymers, respectively. The phase transition at 10.5 mN/m was not observed for the homopolymers alone or for their blends and arises from a brush formation of the PEO segments anchored underneath the adsorbed hydrophobic PCL segments. AFM analysis confirmed the presence of PCL crystals in the LB films with unusual hairlike/needlelike architectures significantly different from those obtained for PCL homopolymers.
通过表面压力测量（等温线和滞后实验）研究了基于聚环氧乙烷和聚己内酯（PEO-b-PCL）的两亲性线性二嵌段共聚物在空气-水（A/W）界面的界面性质。将所得的朗缪尔单分子层转移到云母基底上，并通过原子力显微镜（AFM）研究朗缪尔-布洛杰特（LB）膜的形态。所有嵌段共聚物都具有相同的PEO链段（Mn = 2670 g/mol）和不同的PCL链长度（Mn = 1270；2110；3110和4010 g/mol）。嵌段共聚物样品的等温表征表明在6.5、10.5和13.5 mN/m左右存在三个不同的相变。6.5和13.5 mN/m处的相变分别对应于PEO链段在水亚相中溶解以及PCL嵌段在界面上方结晶，这与相应的均聚物情况类似。单独的均聚物或它们的共混物未观察到10.5 mN/m处的相变，该相变源于锚定在吸附的疏水PCL链段下方的PEO链段形成刷状结构。AFM分析证实LB膜中存在PCL晶体，其具有与PCL均聚物显著不同的异常毛发状/针状结构。
