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Polypropylene with low isotacticity and high molecular weight is synthesized using specific C2-symmetric doubly bridged metallocene complexes. This polymer possesses some isotactic sequences in random order. Though it is the homopolymer of propylene, it is a characteristic polymer having low melting point, transparency and elasticity. This soft polypropylene does not have the drop in the glass transition temperature, and the drop in the compatibility to polypropylene in comparison with propylene copolymer, which is a kind of the conventional soft polypropylene.
This review focuses on using an organic (bio)polymer for the formation of organic/inorganic hybrid materials and on understanding the formation of new hybrid materials via bio-inspired approaches. The structure–function relationships of biomineralization-related proteins and molecular designs to control the properties of the hybrid materials are also described. The combination of experimentation and molecular simulation is also introduced. These studies provide useful ideas for the development of hybrid materials through biomimetic approaches.
Sol–gel transition entropy for k-carrageenan/water and gellan/water systems remains constant, regardless of polymer concentration, and species and concentration of added salts.
The distribution of polarization during the polarization reversal in a VDF/TrFE copolymer was studied by the piezoresponse force microscopy, PFM. After an application of a positive voltage pulse to a negatively polarized sample, PFM image was obtained. The regions of blue color corresponding to positively polarized domains were shown to nucleate and grow in negatively polarized regions (red color) as the duration of pulse increased. The change of each domain with the pulse duration was analyzed quantitatively and the nucleation rate and the growth speed of domains were obtained separately.
Relationships between the interfacial area between PS and PMMA in a PS/PMMA (1/1, w/w) composite particles including various amounts (white circles 0; filled circles 0.05; white triangles 0.11; filled triangles 0.18 (wt % relative to the total amount of PS and PMMA)) of PS-b-PMMA (B11:Mn 10.6 × 104–b-9.9 × 104) and the required time to cleave into two parts (cleavage time, Tc) by addition of the acetone/water (9:1, v/v) solution to the dried particles
Second- and third-generation hydroxy-terminated polyhedral oligomeric silsesquioxane (POSS)-core dendrons (that is, G2POSS-OH and G3POSS-OH, respectively) and third-generation carboxylic acid-terminated POSS-core dendron (G3POSS-COOH) were prepared. Casting of a methanol solution of G3POSS-OH provided optically transparent films. Methanol solution of G2POSS-OH generated opaque whitish films. Casting of a 2.6 m formic acid solution of G3POSS-COOH resulted in a highly transparent free-standing film. The peripheral functional groups may have been exposed on the surface of the cast films, which enabled control of the wettability of the films via the polarity of the COOH groups.
Gelatin nanofibers were electrospun using mild N,N-dimethylacetamide, N,N-dimethylformamide and N-methyl-2-pyrrolidone. Various gelatin nanofibers were fabricated, ranging from a thick, wide, porous nanofibrous structure to a thin, fine, nanofibrous mesh structure, depending on the solvents and their concentrations. In particular, Swiss 3T3 fibroblasts exhibited in vivo-like spindle morphologies on the thick nanofibers. A model protein, alkaline phosphatase, embedded in the gelatin nanofibers maintained high activity.
The alternating copolymers containing planar chiral 4,12-disubstituted[2.2]paracyclophane and quaterthiophene units in the main chain were prepared. The obtained optically active polymers exhibited mirror image Cotton effect, and split in the CD sign that was predicted by the exciton chirality method. A mirror-image CPL response in the polymer solution was also observed with a relatively large glum value on the order of 10–4, suggesting that the polymer forms optically active higher-ordered structures such as zigzag and/or helical structures in the excited state.
It is widely accepted that native xanthan forms a double helical structure and that it loses this structure upon heating (denaturation) and recovers the double helical structure upon cooling its solution (renaturation). The structure of renatured xanthan depends on the concentration of both xanthan and added salt, and temperature. Branched-rods and hairpin-shaped structures were observed by AFM depending on the conditions of denaturation and renaturation. The structural change observed by atomic force microscopy well agrees with the models proposed in our previous study.
![Synthesis of optically active through-space conjugated polymers consisting of planar chiral [2.2]paracyclophane and quaterthiophene](https://media.springernature.com/lw602/springer-static/image/art%3A10.1038%2Fpj.2014.118/MediaObjects/41428_2015_Article_BFpj2014118_Figa_HTML.jpg)
