Hydrodynamic and optical methods were applied to study conformational and physical properties of hyperbranched pyridylphenylene polymers in dilute solutions. The samples were synthesized using Diels–Alder polycyclocondensation. It was demonstrated that hydrodynamic properties of the studied macromolecules were typical for compact non‐percolated spheres. Optical and electro‐optical methods revealed information regarding the shape and asymmetry of the macromolecules (p ≈ 1.4). The contributions of optical shape effect to the observed flow birefringence of polypyridylphenylene solutions and intrinsic anisotropy of polarizability were evaluated and analysed. It was shown that varying the polymer composition (i.e. the degree of branching) caused considerable changes in the anisotropy of optical polarizability of the polymers. Dramatic difference of the electro‐optical properties in non‐polar (toluene) and polar (tetrachloroethane) solvents was found; this difference was related to the orientational correlation of polar solvent molecules with respect to the macromolecules. Dynamic properties were studied by non‐equilibrium electric birefringence which had a reasonable agreement with the dimensions estimated from hydrodynamic data. © 2016 Society of Chemical Industry

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Nano-segregated morphologies and the resulting thermoplastic elastomer (TPE) properties, e.g., in multiblock copolymers based on isoprene (I) and styrene (S), depend on chain architecture (overall molar mass, block number, composition profile). In this work nonconventional (IS) n I type multiblock copolymers possessing two flexible polyisoprene end blocks are introduced. Molar masses between 120 and 400 kg·mol–1 and block numbers ranging from 3 to 13 with either precisely defined blocks or tapered segment structures were obtained by (i) sequential monomer addition or (ii) statistical S/I copolymerization steps, respectively. All polymers are based on a 30/70 molar ratio styrene/isoprene (36 vol % PS). The materials were investigated with respect to their self-assembly and mechanical response, respectively, by small-angle X-ray scattering (SAXS) and tensile tests. While the sequential multiblock copolymers generally exhibited strong segregation into well-ordered lamellar morphologies and more extended chain conformations, their tapered counterparts showed only weak order and a smaller scaling exponent δ with d ∼ N δ. In addition, a higher bridge-to-loop ratio was found for the sequential multiblock copolymers. On the other hand, the tapered structures exhibited accessible order–disorder transition temperatures for low molar masses and high block numbers, which is relevant for processing. Generally, tensile tests revealed high toughness (20–70 MJ·m–3) for the multiblock copolymers bearing at least two polystyrene blocks, with the tapered structures being softer and more flexible. The stiffness also increased with increasing block number, reflecting shrinking of the domain sizes. Moreover, the maximum deformation was found to increase with the overall molar mass. With their soft, albeit resilient properties, these materials with low T g polyisoprene end blocks are promising as a substitute for plasticized polymers, e.g., poly(vinyl chloride), avoiding migration and release of a plasticizer.

The interaction of silver nitrate with star-shaped poly(2-ethyl-2-oxazoline) and poly(2-isopropyl-2-oxazoline) containing central thiacalix[4]arene cores, which proceeds under visible light in aqueous solutions at ambient temperature, was studied. It was found that this process led to the formation of stable colloidal solutions of silver nanoparticles. The kinetics of the formation of the nanoparticles was investigated by the observation of a time-dependent increase in the intensity of the plasmon resonance peak that is related to the nanoparticles and appears in the range of 400 to 700 nm. According to the data of electron and X-ray spectroscopy, scanning and transmission electron microscopy, X-ray diffraction analysis, and dynamic light scattering, the radius of the obtained silver nanoparticles is equal to 30 nm. In addition, the flow birefringence experiments showed that solutions of nanoparticles have high optical shear coefficients.