Synthesis and Structure-Property Relationships of Random and Block Copolymers: A Direct Comparison for Copoly(2-oxazoline)s

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• 作者：Martin W. M. Fijten ; Johannes M. Kranenburg ; Hanneke M. L. Thijs ; Renzo M. Paulus ; Bart M. van Lankvelt ; Jos de Hullu ; Menno Springintveld ; Davin J. G. Thielen ; Catherine A. Tweedie ; Richard Hoogenboo
• 刊名：Macromolecules
• 出版年：2007
• 出版时间：August 7, 2007
• 年：2007
• 卷：40
• 期：16
• 页码：5879 - 5886
• 全文大小：279K
• 年卷期：v.40,no.16(August 7, 2007)
• ISSN：1520-5835

文摘

The purpose of this study was to synthesize copolymers of different molecular architecture, i.e.,monomer distribution over the polymer chain, and to compare their physical and mechanical properties. A seriesof random copolymers of 2-ethyl-2-oxazoline (EtOx) and 2-nonyl-2-oxazoline (NonOx) were synthesized via acationic ring-opening polymerization procedure in acetonitrile under microwave irradiation. The polymerizationkinetics for EtOx and NonOx were studied in refluxing butyronitrile using thermal heating. The resulting kineticdata were applied to synthesize a series of block copolymers with the same chemical composition as the randomcopolymers. The random and block copolymers exhibited the desired composition, molecular weight, and narrowmolecular weight distribution. The surface energies of the random copolymers with 65-85 wt % NonOx werehigher than the surface energy of their block copolymer counterparts as the random distribution of EtOx unitshindered the segregation of the NonOx units to the surface. The variation in polymer architecture also resultedin different phase segregation behavior and different transition temperatures, as shown by differential scanningcalorimetry (DSC). The observed elastic moduli, which differed considerably between the random and the blockseries, were well explained by the phases identified through DSC.