Cylindrical molecular brushes with a loose grafting density |
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| Authors: | Guohua Deng Yongming Chen |
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| Institution: | 1. School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, 510640, People's Republic of China;2. State Key Laboratory of Polymer Physics and Chemistry, Joint Laboratory of Polymer Science and Materials, Institute of Chemistry, The Chinese Academy of Sciences and Beijing National Laboratory for Molecular Sciences, Beijing 100190, People's Republic of China |
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| Abstract: | A cylindrical molecular brush with a low graft density was synthesized by two steps. Firstly, free radical alternating copolymerization of styrene (St) and N‐2‐(2‐bromoisobutyryloxy)ethyl] maleimide (BiBEMI) gave a macroinitiator where pendant initiating sites for atom transfer radical polymerization (ATRP) being positioned along the backbone with an interval of four C? C bonds. The backbone‐to‐be with an alternating sequence was verified by elemental analysis (EA). Secondly, grafting poly(tert‐butyl acrylate) chains from the macroinitiator by ATRP produced the novel molecular brush. Size exclusion chromatography, static light scattering (SLS), and 1H NMR and atomic force microscopy (AFM) were used to characterize the macroinitiator and the molecular brush. The results show that the backbone contains an average 730 repeat units (1 repeat unit = a pair of St and BiBEMI) and the absolute molecular weight of the brush, Mw,SLS, was 4.88 × 106 Da. The brush reveals a number average length Ln to be 96 nm under AFM observation on carbon coated mica, corresponding to the length per main chain monomer unit (Lunit) of 0.066 nm, indicating a less extended conformation due to the low grafting density. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5527–5533, 2009 |
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| Keywords: | ATRP copolymerization graft copolymers molecular brushes |
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