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Effect of counter-anion on the properties and morphology of aliphatic poly(oxytetramethylene) ionenes was investigated, and the relationship between the properties and morphology was elucidated. The ionenes possess elastic properties at low elongations whereas they predominantly exhibit a plastic deformation at high elongations. The morphology of the ionenes was analysed in the nanometer scale by fitting a cascade model for randomly branched f -functional polycondensates incorporated in Debye–Bueche random-two-phase model and the interference term by the interdomain interaction on their small-angle X-ray scattering profiles. The size of ionic domains and distance between the domains were smaller and shorter in the ionene with bromide counter-anion than those in the ionene with chloride counter-anion, respectively. The formation of crystallite of poly(oxytetramethylene) (POTM) segments was detected in the ionene with chloride counter-anion at room temperature. These characteristics of aliphatic POTM ionenes gave the difference in their mechanical and thermal properties.

α,β-Poly(N-hydroxyethyl)- dl -aspartamide (PHEA) and α,β-polyasparthydrazide (PAHy) are synthetic polymers previously studied for biomedical applications. We report here the results of a small-angle X-ray scattering analysis carried out on these two macromolecules in aqueous solution. The data obtained indicate that the two polymers assume remarkably different conformations in aqueous solution, although the backbone is supposed to be the same for the two chains. PHEA can be represented by a random coil conformation, whereas PAHy can be described in terms of an elliptical cylinder characterized by an almost planar structural arrangement with the backbone refolded on itself in a fashion somewhat similar to the β layer of globular proteins. This more rigid conformation of PAHy is related both to the network of hydrogen bonds capable of stabilizing the overall structure and to the lower molecular weight with respect to PHEA. Conformational and energetic analyses of PAHy are also discussed.

The inhomogeneous structure of crosslinked polyurethanes based on poly(butadiene)diol (PBD), 4,4′-diphenylmethane diisocyanate (MDI) and poly(oxypropylene) triol (POPT) prepared with various PBD contents were studied by dynamic mechanical analysis (DMA) and synchrotron small-angle X-ray scattering (SAXS). An inhomogeneous two-phase structure of networks containing PBD was revealed by SAXS. One phase consists of PBD chains while the other of densely crosslinked POPT/MDI network with much higher glass transition temperature. The range of inhomogeneity depends on PBD content, and is estimated as about 70–120 A from the Bragg spacing. The scattering data are fitted using the Percus-Yevick hard sphere model. © 1997 Elsevier Science Ltd.

The process of the microphase separation leading to an inhomogenous structure of the polyurethanes prepared from poly(butadiene)diol (PBD), 4,4′-diphenylmethane diisocyanate (MDI) and poly(oxypropylene)triol (POPT) has been investigated by synchrotron small-angle X-ray scattering (SAXS). The development of the two-phase structure of the polyurethanes, consisting of microdomains of higher electron density dispersed in the matrix of PBD chains, was revealed. When POPT is not used in the preparation, the interdomain distance does not increase with time and it corresponds to the root-mean-square end-to-end distance of the PBD chains. In the presence of POPT a distinct growth in the microdomain size and interdomain distance is observed. The scattering data are discussed in terms of the modified Percus-Yevick hard sphere model. © 1997 Elsevier Science Ltd.

The path-weighting generating function (pwgf) method is applied to calculate the hydrodynamic radii of the randomly crosslinked system as well as its monodisperse faction. Exactly the same relation is found for the z-average reciprocal effective hydrodynamic radius of the linear and the randomly crosslinked system as a function of the weight-average degree of polymerization DPw′, where b〈R h −1 〉 z = C(DP w ) − 1 2 with a constant C depending on the primary chain distribution. The weight-average reciprocal effective hydrodynamic radius, however, depends on the number average degree of polymerization and only moderately changes with crosslinking. The effective hydrodynamic radius of the monodisperse fraction is proportional to the quadratic root of the number of crosslinks. The technique is also applied to the dynamic scattering where formulae for the preaveraged and the non-preaveraged first cumulants are given.

The method of Lagrange's expansion is applied to the bivariate generating function (‘trail-weighting generating function’) previously introduced for combinatorial calculation in polymer science. The wide range of applicability of this method is illustrated by calculation of the moments of the molecular weight distribution function, the Stokes radius and the particle scattering factor of random f -functional branched molecules which are monodisperse (i.e. of fixed molecular weight). The branched molecules in our system are composed of the (random) isomeric mixtures of all possible monodisperse f -functional molecules. This is chemically more realistic than assuming a fixed number of branching units in a molecule, as in Zimm and Stockmayer's, or Kurata and Fukatsu's model. In our model, each branch unit is not necessarily f -functional but the maximum functionality of a branch unit is f , while in an extreme case, the molecule will be linear. Also, the route of the combinatorial calculation is more systematic and appreciably simpler, so that this work helps to clarify the competing effects of branching and polydispersity.