Synthesis, Surface Preparation And Wettability Of Amphiphilic Copolymer PS-g-MPEO

Amphiphilic copolymers containing both hydrophilic and lipophilic groups in the same molecular chain will lead to micro-phase separation.It has a potential application in many respects such as nanomaterials, biomaterials, drug delivery and separation membrane. In selective interface, lipophilic moiety or hydrophilic moiety of amphiphilic copolymers are prone to surface enrichment. It causes change in composition changes and surface properties. In this paper we synthesized amphiphilic graft copolymer PS-g-MPEO by macromonomer, prepared smooth film and rough film of PS-g-MPEO and copolymer mixture, investigated the influence of surface topography on the film surface wettability, explored the surface wettability change under different treatment conditions and explain the change mechanism. The main contents are as follows:1、Synthesized amphiphilic graft copolymer PS-g-MPEO of the different PEO contents by macromonomer method. Purified the product and characterized it by infrared (FT-IR), nuclear magnetic resonance (1H-NMR), gel permeation chromatography (GPC) to analyze its composition and structure.2、PS-g-MPEO smooth and rough film were prepared by dispensed and templated method. The contact angle changes of the film were measured with after annealing and water soaking treatment. Copolymer film surface water contact angles decreased as PEO content increased and water contact angles increased after annealing and decreased after water soaking. The change was more obvious in the rough film because of the increased interfacial area, especially PEO content 45.8% of PS-g-MPEO rough film, in the annealing and water soaking water condition contact angles reduced from 141.6° to 63.1°, film surface changes from hydrophobic into hydrophilic. The molecular chain of flip explain this phenomenon.This is because PEO chains in different processing conditions have different aggregation. Annealing and water soaking can make the PEO chain segment eversion in the macromolecular chains, lead to reversible change of the film surface wettability.3、The TGA result of PS-g-MPEO mixture shows that PS-g-MPEO content in the mixture is 93.26%. That is to say a large number of PS-g-MPEO is wasted in the purification process.So we preapared PS-g-MPEO mixture film,then washed the film to removed impurities. The film were measured with annealing and water soaking treatment after washed and got the film surface water contact angle.The water contact angle has the same change as PS-g-MPEO pure copolymer.We also investigated the effect of annealing temperature on the membrane surface contact angle.