Volume 45 Issue 9, September 2013

Polyion complex (PIC) formation is one of the most powerful techniques for obtaining molecular self-assemblies in aqueous media, and useful for material syntheses particularly in the biomedical field. In this review article, recent progress on PIC vesicles (PICsomes) is summarized. PICsomes are characterized by their simple preparation, semipermeability and environment-sensitivity. Very recently, the methods to control structural uniformity and size of the vesicles have been established, and the potential utility of PICsomes has been expanded by crosslinking their PIC layers. In addition, the unique dynamic nature of PICs is also described.

Using the syndiotactic-rich poly(methacrylic acid) (PMAA), the stereocomplex formation and template effect were investigated. The partially irregular porous isotactic poly(methyl methacrylate) (PMMA) film, which was prepared by syndiotactic-rich PMAA and isotactic PMMA with layer-by-layer method, incorporated the large amount of syndiotactic PMAA, while the template polymerization of methacrylic acid in the porous film did not achieve high syndiotactic PMMA synthesis. The present results suggested the difference of the monomer–polymer interaction and polymer–polymer interaction of PMMA stereocomplex.

Bis-cyclopentadienyl titanium dichloride (Cp₂TiCl₂) is utilized as initiator for aqueous emulsion homopolymerization of 1,3-butadiene and isoprene and for copolymerization of the same diene monomers with styrene. The obtained homo- and copolymers are fully characterized by ¹³C nuclear magnetic resonance spectroscopy, thermal analysis and gel permeation chromatography.

Self-polycondensation of four different AB-type monomers including two novel monomers (monomers C and D) were carried out in the presence of potassium carbonate. High-molecular-weight poly(ether sulfone)s (M_w >110 000) were obtained from monomers C and D.

Effect of α- or β-Copper phthalocyanine (CuPc) as a nucleating agent through crystallization of trans-1,4-polyisoprene (TPI) was evaluated. Observation by polarized optical microscopy showed that the low-melting crystal form is generated at the interface between TPI and either of α- or β-CuPc selectively when crystallized at 38 °C. In differential scanning calorimetry measurements, TPI composites containing α- or β-CuPc showed higher crystallization temperature than that of pure TPI during the cooling process from the melt.

Crystallization kinetics and lamellar structure were revealed for miscible crystalline/crystalline blends of poly(vinylidene fluoride) (PVDF)/isotactic-poly(methyl methacrylate) (i-PMMA). i-PMMA was crystallized following the PVDF crystallization. In the crystallization of i-PMMA under the pre-existing PVDF crystalline lamellar structure, the induction period was considerably shortened compared to that of the neat i-PMMA, and the spacing of the PVDF crystalline lamellae was expanded.

The morphology of PLLA/PBA crystalline/crystalline system reveals abundant morphologies in different crystallization condition. Neat PLLA and PBA usually show Maltese-cross spherulites. However, banded spherulites and branched structures of blends formed in high-temperature region in this work. In addition, fragments morphology is discovered in low-temperature region. These different morphologies are related to the changes of crystallization environment caused by crystalline/crystalline blending.

In the graph, the effect in the antibacterial activity of time and filler content in isotactic polypropylene (iPP)/ZnO composites is reported. Neat iPP has no bactericidal activity. For the composites, a decrease in the E. coli concentration is observed by increasing time. The effect is more evident for iPP/ZnO 95/5.

An original dispositive is used to study the effect of temperature on the conductivity of new materials based mainly on the conducting composites containing poly(aniline) and zeolite, these later exhibit reaction toward the carbon dioxide gas.

A supramolecular polymer consisting of crystalline poly(ethylene adipate) end-functionalized with quadruple hydrogen-bonding ureidopyrimidinone via tolylene unit [PEA-Toly-UPy] were synthesized. When PEA-Toly-UPy was torn, the degree of crystallinity at the torn surfaces was more or less decreased by the energy dissipated by the tearing process.

Diblock functional poly(ɛ-caprolactone)s (PαN₃CL-g-BioM)-b-PCLs grafted with bioactive molecules were performed by Huisgen’s 1,3-dipolar cycloaddition. These amphiphilic copolymers can self-assemble into micelles in the aqueous medium with critical micelle concentration (CMC) in the range 4.6–20 mg l⁻¹, and the average micelle size ranged from 105 to 162 nm. In vitro cell viability assays showed that (PαN₃CL-g-BioM)-b-PCL has low cytotoxicity.

The novel thermoresponsive polycation, poly(N-vinylbutyramide-co-vinylamide) (poly(NVBA-co-VAm)), was synthesized by free radical copolymerization of poly(N-vinylbutyramide-co-N-vinylformamide) (poly(NVBA-co-NVF), followed by acid hydrolysis. The mole ratio of PVAm and PNVBA was varied by adjusting the feeding ratio of NVF and NVBA. PNVBA showed a lower critical solution temperature of 32 °C, while that for poly(NVBA-co-VAm) increased as the VAm mole ratio increased owing to the increasing hydrophilicity, and the more physiologically relevant temperature of 36.5 °C was obtained at a VAm mole ratio of 5%.

Donor–acceptor-type alternate polymers composed of dithienometallole (metal=Si or Ge) and pyridinocalcogenadiazole (chalcogen=S or Se) units were obtained as black solids, which showed highly red-shifted broad bands centered at 732–745 nm in chlorobenzene. Photovoltaic properties of the polymers were examined as blend films with PC₇₀BM and the maximum power conversion efficiency of 3.46% was obtained.

Poly(sodium styrenesulfonate)-block-poly(ethylene glycol)-block-poly(sodium styrenesulfonate) (PSS–PEG–PSS) and poly(methacrylic acid) (PMA) homopolymer were prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization. When aqueous solutions of PSS–PEG–PSS and PMA were mixed below pH 5, water-soluble PSS–PEG–PSS/PMA complexes were formed due to hydrogen bonding interactions between the PEG block and the pendant carboxylic acids in PMA.

Novel nickel–molybdenum–platinum ternary alloy nanoparticles (NiMoPtNPs) stabilized by oleylamine were prepared by a hot-soap method. The following ligand-exchange reaction of oleylamine with 50% N-methylated linear poly(ethyleneimine-co-N-methylethyleneimine) (poly(EI-co-NMEI)) provided poly(EI-co-NMEI)-protected NiMoPtNPs. The average radii of poly(EI-co-NMEI)-protected NiMoPtNPs were 1.9–2.5 nm and were decreased as compared with oleylamine-protected NiMoPtNPs. Poly(EI-co-NMEI)-protected NiMoPtNPs were dispersed in methanol, ethanol and water in the range of pH −1 to 14. The energy-dispersive X-ray spectrometric analysis showed that poly(EI-co-NMEI)-protected NiMoPtNPs are a ternary metal alloy.

Synthetic spider fibers have particular structural and mechanical features that can be improved through extrusion treatments. The surface irregularity, elasticity and strength of fibers are likely to be dependent on their molecular organization and an alcohol bath appears to initiate the transition of random coil structures to β-sheets, resulting in smoother, stronger and more elastic fibers. Atomic force microscopy/force spectroscopy complemented by scanning electron microscopy was able to qualitatively describe synthetic fibers and quantify their roughness and mechanical properties, representing a significant step toward spider silk characterization, and for its application as a biomaterial.