Preparation of Temperature-Sensitive Core−Shell Poly(glycidol)/Poly(N-isopropylacrylamide) Nanohydrogels under Surfactant-Free Conditions

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• 作者：Sebastian Mendrek ; Aleksandra Mendrek ; Hans-Jrgen Adler ; Andrzej Dworak ; Dirk Kuckling
• 刊名：Macromolecules
• 出版年：2009
• 出版时间：November 24, 2009
• 年：2009
• 卷：42
• 期：22
• 页码：9161-9169
• 全文大小：906K
• 年卷期：v.42,no.22(November 24, 2009)
• ISSN：1520-5835

文摘

A new method for synthesis of smart nanohydrogels under additives-free conditions and at high solid content is presented. The new core−shell nanohydrogels with cross-linked poly(N-isopropylacrylamide) (PNIPAAm) core and hydrophilic poly(glycidol) (PGl) shell were obtained by photo-cross-linking of PGl-b-PNIPAAm copolymers above their phase transition temperature (T_c). As UV-active group, the chromophore 2-(dimethylmaleimido)-N-ethylacrylamide (DMIAAm) was synthesized and successfully incorporated in the PNIPAAm segment, while poly(glycidol) chains were responsible for stability of aggregates above T_c. Photo-cross-linkable block copolymers with different PGl length (DP = 55 and 100), DMIAAm chromophore content, and PGl/PNIPAAm block ratio were synthesized for this investigation. It was found that the efficacy of cross-linking strongly depended on the length of PGl block in the copolymer. In the case of copolymers with shorter PGl chains formation of fully cross-linked nanohydrogels was observed already at 45 °C, while for copolymers with longer PGl chains monomodal nanohydrogels were formed at 55 °C. In contrast at given temperature, the rate of cross-linking was independent of chromophore content in copolymer and copolymer composition.