Nanodomain formation in a liquid polymer blend: The initial stages of phase separation

Abstract

Interfacial behavior of phase separated asymmetric compressible binary polymer blendsTheory of domain boundary effects in a phaseseparated mixture of polymer and liquid crystalThe morphology of nanodomain structures in binary polymer blends of a random copolymer and a homopolymer is determined using electronic excitation transport ͑EET͒ studies. The experimental system employed is a copolymer, 6.5% atactic poly͑methyl methacrylate-co-2-vinyl naphthalene͒ ͓P͑MMA-2VN͔͒, in atactic poly͑vinyl acetate͒ ͑PVAc͒. The naphthalene groups serve as chromophores in the EET experiments. The mixtures are prepared such that initially the P͑MMA-2VN͒ chains are randomly distributed in the PVAc matrix. The nanodomains are formed while low-concentration mixtures of the P͑MMA-2VN͒ in PVAc are held at constant temperature in the melt state (TϾT g ), above the temperature at which phase separation occurs. In the melt the chains diffuse, and P͑MMA-2VN͒ chains aggregate until the temperature is quenched below T g . The structures of the resulting domains are examined with time-resolved fluorescence depolarization measurements, and the data are analyzed using an analytical theory to model EET among interacting polymer chains. The agreement between theory and data is very good. The results of the analysis indicate that the nanodomains correspond to aggregates with a characteristic size equal to the radius of gyration of the copolymer, R g . The number of P͑MMA-2VN͒ chains in aggregates prepared under different conditions is determined.

A Dynamical Transition in the Protein Myoglobin Observed by Infrared Vibrational Echo Experiments

“…A way to visualize what might be happening is to consider a hypothetical phase-separated polymer blend in which the minority component, A, is contained in nanometer size domains, 58 , then the host will become liquid at a temperature at which the nanodomains are still solidlike. This changes the boundary condition and could very well reduce the nanodomain glass transition temperature because, for a nanometer-sized object, the surface region has a substantial influence on the interior.…”

Effect of Membrane Microheterogeneity and Domain Size on Fluorescence Resonance Energy Transfer

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Phase Separation in Binary and Ternary Polymer Composites Studied with Electronic Excitation Transport

“…Refined procedures were developed for measuring the extinction coefficient, resulting in a more accurate value for the extinction coefficient than was previously reported. 7 The complete details of the determination of the extinction coefficient appropriate for use in these studies are described in ref 8.…”