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  1. Abstract

    Peptide self‐assembly is fast evolving into a powerful method for the development of bio‐inspired nanomaterials with great potential for many applications, but it remains challenging to control the self‐assembling processes and nanostrucutres because of the intricate interplay of various non‐covalent interactions. A group of 28‐residue α‐helical peptides is designed including NN, NK, and HH that display distinct hierarchical events. The key of the design lies in the incorporation of two asparagine (Asn) or histidine (His) residues at theapositions of the second and fourth heptads, which allow one sequence to pack into homodimers with sticky ends through specific interhelical Asn‐Asn or metal complexation interactions, followed by their longitudinal association into ordered nanofibers. This is in contrast to classical self‐assembling helical peptide systems consisting of two complementary peptides. The collaborative roles played by the four main non‐covalent interactions, including hydrogen‐bonding, hydrophobic interactions, electrostatic interactions, and metal ion coordination, are well demonstrated during the hierarchical self‐assembling processes of these peptides. Different nanostructures, for example, long and short nanofibers, thin and thick fibers, uniform metal ion‐entrapped nanofibers, and polydisperse globular stacks, can be prepared by harnessing these interactions at different levels of hierarchy.

     
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  2. ABSTRACT

    The phase behavior of [6,6]‐phenyl C61‐butyric acid methyl ester (PCBM) blends with amorphous polymers with different degrees of aromaticity has been investigated by differential scanning calorimetry (DSC) and small‐angle neutron scattering (SANS). The polymers investigated are the homologous series of polystyrene (PS), poly(2‐vinyl‐naphthalene) (P2VN), and poly(9‐vinyl‐phenanthrene) (P9VPh). The DSC results show that the miscibility of PCBM in these polymers increases nonlinearly from 16.5 wt % in PS, 57.0 wt % in P2VN, and 74.9 wt % in P9VPh. The SANS results show that at all concentrations of PCBM, the blends are composed of two mixed phases. Analysis shows that the phase dimensions remain largely independent of PCBM content, but there is a strong dependence of the PCBM concentration difference in the two phases with increasing PCBM content. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys.2016,54, 994–1001

     
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