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Synthesis And Characterization Of Grafted Polymer SBS-g-PMMA Via Atom Transfer Radical Polymerization

Posted on:2011-05-12Degree:MasterType:Thesis
Country:ChinaCandidate:P R YuFull Text:PDF
GTID:2211330371463185Subject:Chemical Engineering and Technology
Abstract/Summary:PDF Full Text Request
Because of the good balance of mechanical properties along with favorable processability, the styrene-butadiene-styrene triblock copolymer (SBS) is widely used in various applications, such as footwear, additive of resin, adhesives, asphalt modifier and so on, and is one of the most productive and important thermoplastic elastomers (TPEs). But due to the existence of double bonds, the age resistance of SBS is poor, and it is sensitive to light, heat and oxygen. What's more, the low polarity of SBS leads to the poor resistance to solvent, and the compatibility of SBS with polar material is not good, too. All these disadvantages restrict its application. In order to improve the service performance of SBS to exploit its application, the modification of SBS has been focused by scholars from home and abroad.Considering the disadvantage of low polarity, the polar monomer methyl methacrylate (MMA) was used to modify SBS and a grafted polymer was obtained. The way to get the polymer was not the traditional radical polymerization, but a effective and controlled method, that was atom transfer radical polymerization (ATRP). The process of synthesis can be carried through by two routes:"graft from"and"graft onto", and"click chemistry"was introduced in"graft onto"system.In the first part of this paper, the application, current problems and research situation of SBS were summarized. Then, ATRP and click chemistry were introduced, and the basic theories and application were mentioned briefly, too.The synthesis of grafted polymer SBS-g-PMMA with"graft from"method was expatiated in the second part. Firstly, the hydroxylated SBS (SBS-OH) was synthesized, then the chlorinated SBS (SBS-Cl) was prepared by reacting with chloroacetic chloride. Finally, the grafted polymerization was carried through ATRP with SBS-Cl as a macroinitiator. The structures of each product were characterized by fourier transform infrared spectrometer (FTIR) and proton nuclear magnetic resonance (1H-NMR), and X-ray photoelectron spectroscopy (XPS) was used to confirm the existence of chlorine. Furthermore, the properties of the grafted polymer were characterized by gel permeation chromatography (GPC), thermogravimetric analysis (TGA) and atomic force micrograph (AFM). Besides, the synthesis conditions of SBS-OH were also investigated in this part.In the last part of the paper, the synthesis of SBS-g-PMMA with"grafted onto"method was elaborated. The acetylenic SBS (SBS-C≡CH) and azido-functionalized side chains PMMA-N3 were obtained firstly, then combined together by click chemistry method with CuBr as catalyzer. The structures of products were also characterized by FTIR and ~1H-NMR.
Keywords/Search Tags:SBS, Grafted modification, Atom transfer radical polymerization (ATRP), Click chemisty
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