The sophisticated use of self-organizing materials, which include liquid crystals, block copolymers, hydrogen- and π-bonded complexes, and many natural polymers, may hold the key to developing new structures and devices in many advanced technology industries. Synthetic materials are usually designed with only one structure-forming process in mind. However, combination of both complementary and antagonistic interactions in macromolecular systems can create order in materials over many length scales. Here polymer materials that make use of competing molecular interactions are summarized, and the prospects for the further development of such materials through both synthetic and processing pathways are highlighted.
The average residence time τ of a polymer of length N passing through a narrow hole under a chemical potential gradient is calculated. In the proposed model, details of the hole parametrize the rate constant k0 for transporting a monomer across the hole, independent of the chain length. We show that any asymmetry in the average conformations of the polymer across the hole is sufficient to generate the driving force for the polymer translocation. If chemical potential gradient is absent, τ∼N2, with the proportionality constant depending on the size exponent of the polymer before and after the translocation. For translocation along the chemical potential gradient Δμ, τ is proportional to N(T/k0Δμ) and N2/k0, respectively, for large and small NΔμ/T. For translocation against the chemical potential gradient, τ∼exp(N) for long polymers.
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