Macromolecular Rapid Communications

Kim, GeunHyung; Son, JoonGon; Park, SuA; Kim, WanDoo

doi: 10.1002/marc.200890038pmid: N/A

Cover: The image shows a hybrid polymeric scaffold that was fabricated using a rapid prototyping (RP) method and electrospinning process. The panels clearly indicate that the layers of electrospun micro‐/nanofibers are located between the layers of dispensed poly(ε‐caprolactone) strands. Further details can be found in the article by G.‐H. Kim,* J.‐G. Son, S.‐A. Park, and W.‐D. Kim on page 1577.

doi: 10.1002/marc.200890039pmid: N/A

Kakiage, Masaki; Uehara, Hiroki; Yamanobe, Takeshi

doi: 10.1002/marc.200800316pmid: N/A

A novel in situ measurement system for evaluating molecular mobility during uniaxial drawing of polymeric materials was established by introducing drawing and stress‐detecting devices into a 1H pulse nuclear magnetic resonance spectrometer. In this study, we analyze the changes in molecular motion of amorphous chains during melt‐drawing of ultra‐high molecular weight polyethylenes (UHMW‐PEs) with different molecular weight distributions. In the initial stage of drawing, a three‐component resolution was possible for the relaxation decay curve, which includes “rigid”, “intermediate”, and “mobile” amorphous components. The quality and quantity changes in these components demonstrated that this intermediate amorphous component could be regarded as the index of the change in molecular entanglement characteristics during the orientation of PE chains.

Kim, GeunHyung; Son, JoonGon; Park, SuA; Kim, WanDoo

doi: 10.1002/marc.200800277pmid: N/A

An ideal scaffold should have good mechanical properties and provide a biologically functional implant site. A rapid prototyping system has been introduced as a good method of fabricating 3D scaffolds that mimic the structure in the human body. However, the scaffolds have strands that are too smooth and a pore size that is too large relative to the seeded cells and present unfavorable conditions for initial cell attachment. To overcome these problems, we propose a hybrid technology combining a 3D rapid prototyping system and an electrospinning process to produce a hierarchical 3D biomedical scaffold. The resulting structure consists of alternating layers of 3D‐structured/microsized polymer strands and nanofiber webs. The results of cell culturing of chondrocytes indicate that this technique is a feasible new method for fabricating high quality 3D polymeric scaffolds.

Maity, Arjun; Sinha Ray, Suprakas

doi: 10.1002/marc.200800356pmid: N/A

In this communication, the synthesis, characterization, and properties of highly conductive core–shell nanocomposites of poly(N‐vinylcarbazole) (PNVC)–polypyrrole (PPY) copolymers with multi‐walled carbon nanotubes (MWCNTs) are described. A unique free‐radical coupling reaction between PNVC and PPY cation radicals in chloroform solvent, using feric chloride as an oxidant, in the presence of suspended MWCNTs in the reaction medium, was used for the synthesis of nanocomposite. Field‐emission scanning and transmission electron microscopy studies showed the formation of the core–shell nanocomposite. Raman spectrocopy results as well as thermogravimetric analysis supported the electron microscopic observations. The resulting PNVC–PPY copolymer‐coated MWCNTs showed an unprecedentedly increased value of direct electrical conductivity (bulk) compared to the conductivity of all samples even with pure MWCNTs.

Lv, Jing; Ouyang, Canbin; Yin, Xiaodong; Zheng, Haiyan; Zuo, Zicheng; Xu, Jialiang; Liu, Huibiao; Li, Yuliang

doi: 10.1002/marc.200800256pmid: N/A

A novel water‐soluble poly(para‐phenylene) derivative with pendant thymine and sulfonate units (PBTS) has been prepared and its metal ion sensing properties have been investigated. PBTS exhibited a reversible and selective fluorescence quenching behavior toward Hg2+ ions as compared to Ag+, Ni2+, Mg2+, Ca2+, Hg2+, Co2+, Cd2+, Cu2+, Pb2+, Ba2+, Fe3+, and Zn2+ ions in aqueous solution. The fluorescence quenching resulted from the interpolymeric π‐stacking aggregation which was induced by the specific thymine–Hg–thymine interaction.

Michinobu, Tsuyoshi; Fujii, Nozomu; Tokita, Masatoshi; Watanabe, Junji; Shigehara, Kiyotaka

doi: 10.1002/marc.200800363pmid: N/A

Two types of liquid crystal poly(fumarate)s having cyanobiphenyl mesogen in side chain were prepared by radical polymerization of disubstituted fumarate monomers in bulk. The mesogen is thus connected via alkyl spacer to every carbon atom in the main chain. The liquid crystalline temperature range expands with an increase in the molecular weight and with alkyl chain spacer length. The poly(fumarate)s form a smectic Ad phase whose layer spacing decreases and increases on heating and cooling, respectively. The contraction ratio is up to 15.2%. This significantly large change in the layer spacing corresponds to temperature dependence of the orientational order parameter. It may be connected to high density of the mesogen hanging from the main chain.

Sen, Mustafa Y.; Puskas, Judit E.; Ummadisetty, Subramanyam; Kennedy, Joseph P.

doi: 10.1002/marc.200800359pmid: N/A

Methacrylate‐terminated polyisobutylenes (PIB‐MAs) were synthesized by transesterification of vinyl methacrylate by hydroxyl‐terminated polyisobutylenes (PIB‐OH) using Candida antarctica lipase B (Novozyme 435) catalyst in hexane at 50 °C. PIBCH2CH2CH2OH and GlissopalOH, synthesized by anti‐Markovnikov hydrobromination of allyl‐terminated PIB and Glissopal®2300 followed by hydrolysis, were quantitatively converted into the corresponding PIB‐MAs. 1H and 13C NMR spectroscopy verified the formation of the expected structures. This “green” chemistry is a very promising methodology for polymer functionalization in general, and biomaterial synthesis in particular.

Zhang, Wei; Li, Jun; Zhang, Bao; Qin, Jingui

doi: 10.1002/marc.200800336pmid: N/A

Three copolymers that incorporate dithieno(3,2‐b:2′,3′‐d)pyrrole with fluorene, carbazole, or pyridine have been prepared by Suzuki reaction and characterized by NMR spectroscopy and GPC. A new homopolymer of dithieno(3,2‐b:2′,3′‐d)pyrrole was also synthesized for the comparison of their structure–property relationships. Their thermal, optical, and electrochemical properties have been investigated. All the polymers exhibit good thermal stability with decomposition temperatures around 400 °C. The fluorescence quantum efficiencies of all these polymers in solution are in the range of 33.5–55.5%. The copolymers also show high film fluorescence quantum efficiencies of about 20% while the fluorescence of the homopolymer film is almost quenched.

Costa, Liborio Ivano; Kasëmi, Edis; Storti, Giuseppe; Morbidelli, Massimo; Walde, Peter; Schlüter, A. Dieter

doi: 10.1002/marc.200800250pmid: N/A

Radical polymerizations from third to fifth generation macromonomers were conducted in supercritical carbon dioxide (scCO2). It was found that all monomers were not soluble in such a medium, and reactions occurred in the CO2‐swollen monomer matrices. Despite the expected severe diffusion limitations, very high conversions and molecular weights were obtained. It is believed that the plasticization effect induced by the CO2 plays a key role in these surprising findings. Scanning force microscopical analyses confirmed that mainly linear dendronized polymers were obtained and therefore chain transfer to polymer is virtually irrelevant.