Diblock fluoroacrylate copolymers from two initiators: synthesis, self-assembly and surface properties
作者:Xia Dong、Ling He、Na Wang、Jun-Yan Liang、Ming-Jun Niu、Xiang Zhao
DOI:10.1039/c2jm35400d
日期:——
Diblock fluoroacrylate copolymers poly(methyl methacrylate) (PMMA)-b-poly(dodecafluoroheptyl methacrylate) (PMMA-b-PDFHM) for coating materials are synthesized via atom transfer radical polymerization (ATRP) by two different initiators, a brominated initiator end group terminated by 1H,1H,2H,2H-heptadecafluoro (F–Br) and the conventional initiator ethyl 2-bromoisobutyrate (EBiB). The copolymer structures are characterized by 1H NMR, 19F NMR and GPC analyses. The influence of the two initiators on the self-assembly behavior and the surface properties of PMMA-b-PDFHM films are explored. Because of the divergent solubility of the segments in chloroform (CHCl3), tetrahydrofuran (THF) and trifluorotoluene (TFT) solutions, the self-assembly of PMMA-b-PDFHM in CHCl3, THF and TFT was investigated using dynamic light scattering (DLS) and transmission electron microscopy (TEM). Accordingly, the properties of PMMA-b-PDFHM films cast from CHCl3, THF and TFT solutions were compared for their surface wettability, surface free energy, surface elemental composition, surface morphology and roughness, and surface water adsorption, through analysis of static contact angle (SCA), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and quartz crystal microbalance with dissipation (QCM-D). It is found that the copolymers F-PMMA-b-PDFHM using F–Br initiator and E-PMMA-b-PDFHM using EBIB initiator, reveal both unimers (7–9 nm) and micelles (220–360 nm) in THF and CHCl3 solutions, which are recognized by TEM as dichroic half-spherical or core–shell particles, but occur mainly as unimers (5–9 nm) in TFT solution, which is favorable for obtaining films with low surface free energies. F-PMMA-b-PDFHM films show lower surface free energy (17.1–17.7 mN m−1) than E-PMMA-b-PDFHM films (17.9–22.9 mN m−1) in each solvent. The surface morphology and roughness determined are strongly controlled by the cast solutions. F-PMMA-b-PDFHM films exhibit a low wettability and high stable surface due to a well-ordered fluorocarbon surface provided by both PDFHM and F–Br groups, and therefore can be developed into a high-performance coating material.
通过原子转移自由基聚合(ATRP)法合成了用于涂层材料的聚甲基丙烯酸甲酯(PMMA)-b-聚甲基丙烯酸十二氟庚酯(PMMA-b-PDFHM)双嵌段氟丙烯酸酯共聚物,该共聚物由两种不同的引发剂合成,一种是以 1H,1H,2H,2H-十七氟(F-Br)为端基的溴化引发剂端基,另一种是传统引发剂 2-溴异丁酸乙酯(EBiB)。共聚物结构通过 1H NMR、19F NMR 和 GPC 分析进行表征。研究还探讨了两种引发剂对 PMMA-b-PDFHM 薄膜的自组装行为和表面特性的影响。由于这些片段在氯仿(CHCl3)、四氢呋喃(THF)和三氟甲苯(TFT)溶液中的溶解度不同,因此使用动态光散射(DLS)和透射电子显微镜(TEM)研究了 PMMA-b-PDFHM 在 CHCl3、THF 和 TFT 溶液中的自组装情况。相应地,通过静态接触角 (SCA)、X 射线光电子能谱 (XPS)、扫描电子显微镜 (SEM)、原子力显微镜 (AFM) 和带耗散的石英晶体微天平 (QCM-D),比较了从 CHCl3、THF 和 TFT 溶液中浇铸的 PMMA-b-PDFHM 薄膜的表面润湿性、表面自由能、表面元素组成、表面形貌和粗糙度以及表面吸水性等特性。研究发现,使用 F-Br 起始剂的共聚物 F-PMMA-b-PDFHM 和使用 EBIB 起始剂的共聚物 E-PMMA-b-PDFHM,在 THF 和 CHCl3 溶液中均显示出单聚物(7-9 nm)和胶束(220-360 nm),TEM 可将其识别为二向色半球形或核壳颗粒,但在 TFT 溶液中主要以单聚物(5-9 nm)出现,这有利于获得表面自由能较低的薄膜。在各种溶剂中,F-PMMA-b-PDFHM 薄膜的表面自由能(17.1-17.7 mN m-1)均低于 E-PMMA-b-PDFHM 薄膜(17.9-22.9 mN m-1)。所确定的表面形态和粗糙度在很大程度上受浇注溶液的控制。由于 PDFHM 和 F-Br 基团提供了一个有序的碳氟化合物表面,F-PMMA-b-PDFHM 薄膜表现出低润湿性和高稳定性的表面,因此可以开发成一种高性能涂层材料。