[en] Selectivity in inter polymer complex formation involving a typical four-component phenolic copolymer (ρ-chloro phenol-ρ-aminophenol-ρ-toluidine-ρ-cresol- HCHO copolymer), poly electrolytes such as polyethylene imine and polyacrylic acid, a non-ionic homopolymer polyvinyl pyrrolidone, and some transition metal ions (e.g., Cu (II), Ni (11)) have been studied in dimethylformamide-methanol solvents mixture. The coordinating groups of phenolic copolymer form complexes through hydrogen bonding and ion-dipole interactions. The different stages of interactions have been studied by several experimental techniques, e.g., viscometry, potentiometry and conductometry. Some schemes have been suggested to explain the mode of interaction between these components

[en] Analysis of dynamic properties of a simple globular protein, myoglobin, has demonstrated that it possesses a hierarchically organized energy landscape. It shows two types of specific protein motions, besides vibrations: 1) individual motions of small atomic groups - transitions between conformational substates (CS) of the lower tier 2, and 2) cooperative motions of secondary structure elements ( α-helices) - transitions between CS of the upper tier 1. The profile of macromolecule dynamic properties is highly heterogeneous. Only vibrations occur near the active center. The number of CS grows towards the periphery where specific type 1 and 2 motions become predominant. Such a picture is consistent with the concept of a protein as 'a random copolymer slightly edited in the vicinity of the active center'. (reviews of topical problems)

[en] The surface structure of a lamellar polystyrene-block-polybutadiene-block-polymethylmethacrylate (SBM) triblock copolymer forms a complex reconstruction, which breaks the two-dimensional continuous translational symmetry of an ideal (homogeneous) SBM surface. Despite the very different types of matter and order, our findings reveal a remarkable analogy with the well-known phenomenon of surface reconstruction of single crystals, in particular, with the (2 x 1) ''buckling row'' reconstruction of the Si(100) surface. Similarities and differences between both classes of materials are discussed on the basis of symmetry considerations

[en] Bicontinuous morphologies are ubiquitous in nature and occur at various length scales. Topological features of two such morphologies arising in an ordered block copolymer at equilibrium and a polymer blend during spinodal decomposition are measured from three-dimensional images. Interfacial curvature, coordination number, and interjunction distance distributions exhibit remarkable similarity in these systems, despite vastly different length scales. A channel coordination of 3 is dominant in both morphologies, and topological measurements such as the Euler-Poincare characteristic and genus are reported

No abstract available

[en] Hydrogels are polymers characterized by their ability to absorb a considerable amount of water. Hydrogels consist of polymer molecules physically or chemically crosslinked, forming a molecular network, so that in water they swell to an equilibrium value, preserving their shape [1]. The aim of this work was to prepare by gamma radiation poly (2-hydroxyethyl methacrylate-co-acrylamide) hydrogels, p(HEMA-co-AAm), doped with Nanoclay (laponite XLG). (Author)

[en] A centrosymmetric polymer precursor, 4-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl)butan-1-amine (TPBA), was synthesized via a Knorr–Paal reaction and its copolymer with EDOT was electrochemically synthesized and characterized. While P(TPBA) has only two colors in its oxidized and neutral states, its copolymer with EDOT has eight different colors. Electrochromic devices based on P(TPBA)/PEDOT and P(TPBA-co-EDOT)/PEDOT were constructed and characterized. The oxidized state of the device shows blue color whereas it shows purple for the reduced state. At moderate potentials the device has good transparency with green and gray colors. The maximum contrast and switching time of the multielectrochromic copolymer device were measured as 25% and 0.8 s at 575 nm. Copolymerization not only increases the polymer’s color scheme, but also improves its properties, such as redox stability and switching time. (paper)

No abstract available

[en] The maximum stress and strain at break remained high and stable after MDI-mediated crosslinking. Similarly, shape recovery and shape retention tests also showed excellent and reproducible results. The MDI-mediated crosslinking was responsible for the interesting tensile and shape memory results. Therefore, it was demonstrated in this investigation that the allophanate type crosslinking, unlike previous misleading information, was possible under the mild reaction conditions. Polyurethane (PU) has long been investigated due to its excellent mechanical properties, shape memory effect, and biocompatibility, and was grafted with pendant functional groups to tailor the polymer characteristics without affecting their basic structure. Actually, polyethyleneglycol has been grafted to polyurethane to improve biocompatibility in biomedical applications, and low temperature flexibility could be improved by the pendant naphthol group grafted to PU. In the field of shape memory polyurethane, mechanical and shape memory properties could be improved by terminal crosslinking with glycerol, pentaerythritol, and dextrin. Alternatively, a flexible crosslinking method was devised to demonstrate both high mechanical strength and shape recovery

[en] This work presents the synthesis of magnetite nanoparticle (MNP) coated with poly(N,N-diethylaminoethyl methacrylate)-b-poly(N-isopropyl acrylamide-st-thiolactone acrylamide) (PDEAEMA-b-P(NIPAAm-st-TlaAm) copolymer and its use in controlled drug release and bio-conjugation. TlaAm units in the copolymer were ring-opened with various alkyl amines to form thiol groups (-SH), followed by thiol-ene coupling reactions with acrylamide-coated MNP and then quaternized to obtain cationic copolymer-MNP assemblies (the size < 200 nm/cluster). The use of alkyl amines having various chain lengths (e.g., 1-propylamine, 1-octylamine, or 1-dodecylamine) in the nucleophilic ring-opening reactions of the thiolactone rings affected their magnetic separation ability, water dispersibility, and release rate of doxorubicin model drug. In all cases, when increasing the temperature, they showed a thermo-responsive behavior as indicated by the decrease in hydrodynamic size and the accelerated drug release rate. These copolymer-MNP assemblies could be used as a novel platform with thermal-triggering controlled drug release and capability for adsorption with any negatively charged biomolecules. .