Environmental Dependency of Weak Attractive Interactions of Polymers and Their Applications to Molecular Design of Polymers

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(1) Solution properties of poly (ethylene imine) Light scattering (LS) experiments on poly (ethylene imine) (PEI) have been conducted to find the theta conditions and to evaluate the unperturbed chain dimension. The sample preparation of PEI has been adapted for the LS measurements: after hydrolysis of the precursor polymer, the residual hydrochloric acid was neutralized with ammonia, and PEI thus obtained was purified by dialysis and fractionated. Well-defined Zimm plots were obtained from the ethanol solutions, but the data indicate that PEI chains are aggregated even in dilute solutions. We will continue to search for the theta renditions, for example, by adding inorganic salt (s) into the aqueous solution and analyze the aggregate structure formed in the ethanol solutions.(2) Crystal structure determination by the ab initio molecular orbital (MO) calculations Crystal structures of anhydrous and 0.5- 1.5-, and 2.0-hydrous PEIs have been optimized by ab initio MO calculations with di … More fferent theories and basis sets under three-dimensional periodic boundary conditions. For three polyselenoethers to be mentioned below, the crystal structures were successfully determined, and their electronic structures, electronic properties, and optical properties were predicted.(3) Conformational analysis of polyselenoethers Conformational characteristics of poly (methylene selenide), poly (ethylene selenide), and poly (trimethylene selenide) have been elucidated and discussed by comparison with those of related polyethers and polysulfides, and their crystal structures and physical properties were also characterized; that is, the higher structures and physical properties were predicted from the primary structures.(4) Prediction and characterization of polymers with different heteroatoms Conformations, secondary structures, and crystal structures of poly (ethylene imine-alt-ethylene oxide), poly (ethylene imine-alt-ethylene sulfide), and poly (ethylene oxide-alt-ethylene sulfide) have been predicted and well characterized by abinitio MO calculations and the rotational isomeric state scheme. The above (3) and present studies have afforded actual examples of molecular design for polymers. Less