Unique Interphase and Cross-Linked Network Controlled by Different Miscible Blocks in Nanostructured Epoxy/Block Copolymer Blends Characterized by Solid-State NMR
作者：Xin He, Yuan Liu, Rongchun Zhang, Qiang Wu, Tiehong Chen, Pingchuan Sun, Xiaoliang Wang, and Gi Xue
關(guān)鍵字：epoxy resin, block copolymer, interphase, hydrogen bonds, solid-state NMR
論文來源：期刊
具體來源：J. Phys. Chem. C 2014, 118, 13285
發(fā)表時(shí)間：2014年
A variety of multi-scale solid-state NMR techniques were used to characterize the heterogeneous structure and dynamics of the interphase and cross-linked network in nanostructured epoxy resin/block copolymer (ER/BCP) blends, focusing on the role of ER-miscible blocks containing poly(ε-caprolactone) (PCL) or poly(ethylene oxide) (PEO) blocks having different intermolecular interactions with ER. 1H spin-diffusion experiments indicate that the interphase thickness of PEO-containing blends is obviously smaller than that of PCL-containing blends. High-resolution 1H fast MAS spin-exchange experiments reveal detailed interfacial mixing between ER and BCPs for the first time, and two different types of interphase structure are found. 1H fast MAS DQ filter experiment provides a fast and convenient detection of interphase composition, including immobilized BCPs and partially cured or local damaged ER network. The driving force for the interphase formation and miscibility in PCL-containing blends is successfully determined by high-resolution 13C CPMAS experiments, demonstrating the formation of hydrogen bonds between PCL and ER, and competing hydrogen bonding interactions were also found when ER was blended with PEO-b-PCL (EOCL). A new calculation method was proposed to quantitatively determine the distribution of different blocks in the interphase and dispersed phase for PCL-containing blends in combination with 13C CPMAS and 1H spin-diffusion experiments. 13C T1 spin-lattice relaxation experiment provides a quantitative determination of the amount of local destroyed network in the interphase. Furthermore, it was found that incorporation of BCPs induces unexpected enhanced rigidity of cross-linked network. On the basis of NMR results, we proposed a model to describe the unique structure and dynamics of the interphase and cross-linked network as well as their underlying formation mechanism in ER/BCP blends.