Spectroscopie analysis of epoxy/ block-copolymer blends

Abstract

Epoxy/block copolymer blends exhibit unique nanostructure, morphologies, phase behavior, and physical properties, which are determined by the cross-linking reaction of the thermosetting resin, the self-assembly of the block copolymer, and the process of phase separation. Understanding of the influence of different types of ER-miscible blocks on the microdomain structure and dynamics, as well as the underlying molecular mechanism responsible for the structure formation and evolution in these blends is still lacking at a molecular level. In this chapter, a variety of advanced multiscale solid-state NMR techniques were used to charac-terize the heterogeneous dynamics, miscibility, microdomain, and interphase structure, as well as the cross-linked network in nanostructured epoxy/block copolymer (ER/BCP) blends, focusing on the role of ER-miscible blocks containing poly(e-caprolactone) (PCL) or poly(ethylene oxide) (PEO) blocks having different intermolecular interactions with ER. 1H static and magic-angle spinning (MAS) experiments were used to detect the molecular mobility in these blends, and then detailed dynamic behavior and the miscibility of the BCPs with the cured-ER network were obtained by 1H dipolar filter experiments. Two-dimensional 13C-1H WISE experiment was used to gain information about the heterogeneous dynamics of individual components and to determine the extent of phase separation in the blends. 1H dipolar filter spin-diffusion experiments were used to quantitatively determine the evolution of interphase thickness. High- resolution 1H DQ filter and 1H-1H spin-exchange experiments under fast MAS were utilized to detect interphase composition and detailed intermolecular prox-imity between ER and BCPs in the interphase region. High-resolution 13C CPMAS experiments were employed to probe the driving force for the interphase formation and miscibility associated with the intermolecular interactions between ER and ER-miscible blocks. Finally, 13C Ti spin-lattice relaxation experiments were used to quantitatively determine the amount of local destroyed network and dynamics of cross-linked network in all blends. On the basis of these NMR results, we proposed a model to describe the unique structure and dynamics of the interphase and cross-linked network, as well as the underlying mechanism respon-sible for the nanostructure formation in ER/BCP blends with different ER-miscible blocks.