Poly(2-cyclopropyl-2-oxazoline): From Rate Acceleration by Cyclopropyl to Thermoresponsive Properties

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• 作者：Meta M. Bloksma ; Christine Weber ; Igor Y. Perevyazko ; Anette Kuse ; Anja Baumga虉rtel ; Antje Vollrath ; Richard Hoogenboom ; Ulrich S. Schubert
• 刊名：Macromolecules
• 出版年：2011
• 出版时间：June 14, 2011
• 年：2011
• 卷：44
• 期：11
• 页码：4057-4064
• 全文大小：954K
• 年卷期：v.44,no.11(June 14, 2011)
• ISSN：1520-5835

文摘

The synthesis and microwave-assisted living cationic ring-opening polymerization of 2-cyclopropyl-2-oxazoline is reported revealing the fastest polymerization for an aliphatic substituted 2-oxazoline to date, which is ascribed to the electron withdrawing effect of the cyclopropyl group. The poly(2-cyclopropyl-2-oxazoline) (pCPropOx) represents an alternative thermo-responsive poly(2-oxazoline) with a reversible critical temperature close to body temperature. The cloud point (CP) of the obtained pCPropOx in aqueous solution was evaluated in detail by turbidimetry, dynamic light scattering (DLS) and viscosity measurements. pCPropOx is amorphous with a significantly higher glass transition temperature (T_g 80 掳C) compared to the amorphous poly(2-n-propyl-2-oxazoline) (pnPropOx) (T_g 40 掳C), while poly(2-isopropyl-2-oxazoline) piPropOx is semicrystalline. In addition, a pCPropOx comb polymer was prepared by methacrylic acid end-capping of the living cationic species followed by RAFT polymerization of the macromonomer. The polymer architecture does not influence the concentration dependence of the CP, however, both the CP and T_g of the comb polymer are lower due to the increased number of hydrophobic end groups.