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1.
The gecko adhesion phenomenon has stimulated efforts to produce synthetic patterned dry adhesives. Besides introducing surface patterns on dry adhesives, it is also highly desirable to understand their intrinsic material properties. This communication reports the viscoelastic behavior of non‐patterned epoxy elastomers exhibiting intrinsic adhesion that is much higher than that of elastomers typically used for structure patterning. The diverse molecular origin of the adhesion is revealed through the study of adhesion against various substrates.
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Aaron C. Jackson Jonathan A. Bartelt Kamil Marczewski Nancy R. Sottos Paul V. Braun 《Macromolecular rapid communications》2011,32(1):82-87
A generalized silica coating scheme is used to functionalize and protect sub‐micron and micron size dicyclopentadiene monomer‐filled capsules and polymer‐protected Grubbs' catalyst particles. These capsules and particles are used for self‐healing of microscale damage in an epoxy‐based polymer. The silica layer both protects the capsules and particles, and limits their aggregation when added to an epoxy matrix, enabling the capsules and particles to be dispersed at high concentrations with little loss of reactivity.
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Seung June Park Min Seong Cho Sung Taek Lim Hyoung Jin Choi Myung S. Jhon 《Macromolecular rapid communications》2003,24(18):1070-1073
Multi‐walled carbon nanotubes (MWNT) purified by acidic solution were processed with PMMA via an in‐situ polymerization. Experimental evidences indicate the role of radical initiator (AIBN) and MWNT, showing increases of polymerization rate and MWNT diameter. Induced radicals on the MWNT by AIBN were found to trigger the grafting of PMMA. Moreover, the solvent cast film showed a better nanoscopic dispersion of MWNT and possibilities of CNT composites in engineering applications.
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Subramanian Sundarrajan Kalathur S. V. Srinivasan 《Macromolecular rapid communications》2003,24(12):724-731
A series of poly(acyl sulfides) were synthesized by polycondensation of acid dichlorides with sodium sulfide using tetrabutylammoniumhydrogen sulfate as a phase transfer catalyst. The thermal stability of these polymers was determined by thermogravimetric analysis. A unique phenomenon of exothermic degradation behavior was observed by differential thermal analyses, which is attributed to the energetics of the acylsulfide linkage during the thermal degradation. The mechanism of formation of degradation products was investigated by the pyrolysis–gas chromatography/mass spectrometry (Py‐GC/MS) technique.
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Junsheng Wang Jixiao Wang Zhi Wang Fengbao Zhang 《Macromolecular rapid communications》2009,30(8):604-608
Urchin‐like PANI microspheres with an average diameter of 5–10 µm have been successfully prepared. Their surfaces consist of highly oriented nanofibers of ≈30 nm diameter and 1 µm length. The solvent composition plays an important role in the formation process of urchin‐like PANI microspheres. The structure of the products has been characterized by FT‐IR, UV‐vis, and XRD. To investigate the self‐assembly of urchin‐like PANI microspheres, the effect of polymerization time on the morphology of the products has been studied. The morphological evolution process indicates that the urchin‐like microspheres originate from the self‐assembly of nanoplates, which then grow into urchin‐like microstructures with nanofibers on the surface.
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The preparation of self‐assembled polyaniline (PANi) microspheres via facile interfacial oxidation polymerization of aniline in the presence of DL ‐tartaric acid dopant is reported. Compared with PANis reported in the literature, the PANi prepared in this study exhibits a nanorod‐bundle morphology with exceptionally high crystallinity. These nanorods or nanorod bundles can self‐assemble into microspheres with unique alignment. The chemistry, morphology, and crystal structure of DL ‐tartaric acid doped microspheres were studied using SEM, TEM, SAED, XRD, and FTIR.
8.
A photochemical approach toward the generation of enzyme‐containing redox polymer networks, which are the key material in enzymatic sensors and biofuel cells, is described. The approach is based on the incorporation of photo‐reactive benzophenone groups into the redox polymers. The obtained polymers are then deposited on the surface of glassy carbon electrodes and cross‐linked by illumination with UV light at 365 nm. If this step is done in the presence of the enzyme glucose oxidase, functional electrodes are obtained that yield electrical power upon addition of glucose. This work specifically addresses the question of electrode stability in buffer and demonstrates how slight variations in the chemistry of the redox polymer have a dramatic effect on the electrochemical performance of the electrodes. Different ferrocene‐containing redox polymer networks are synthesized and their properties in physiological buffer are studied.
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Summary: A composite film composed of porous polyurethane (PU) and polystyrene (PS) microspheres with both superhydrophobicity and superoleophilicity has been prepared. In this film, the dual‐scale structure enhances both the hydrophobicity and oleophilicity of the surface material. The composite film with such an ‘intelligent’ wettability property can be utilized to separate oil and water systems efficiently.
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Graft chitosan derivatives (CMCTS‐g‐MAAS and CMCTS‐g‐AAS) were prepared by the graft copolymerization of methacrylic acid sodium (MAAS) and acrylic acid sodium (AAS) onto the etherification product of chitosan‐carboxymethyl chitosan (CMCTS). Their antioxidant activity was estimated as superoxide anion scavengers by chemiluminescence techniques. The derivatives with low grafting percentages have a relatively low 50% inhibition concentration (IC50), which could be related to the fact that they have different contents of hydroxyl and amino groups in the polymer chains.
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Yunze Long Lijuan Zhang Yongjun Ma Zhaojia Chen Nanlin Wang Ze Zhang Meixiang Wan 《Macromolecular rapid communications》2003,24(16):938-942
Camphor sulfonic acid (CSA) doped polyaniline (PANI) nanotubes (175 nm in outer diameter and 120 nm in inner diameter) were synthesized successfully by a self‐assembly method. It is found that the room‐temperature conductivity of an individual PANI nanotube is 30.5 S · cm−1; in particular, the intrinsic resistance of an individual nanotube (30 kΩ) is much smaller than the contact resistance of crossed nanotubes (500 kΩ).
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Micro‐Raman spectroscopy has been used to investigate the chemical micro‐heterogeneity of multiphase‐separated poly(ether urethanes) (PETU). Analysis of PETU cross‐sections by means of micro‐Raman spectroscopy revealed the nearly complete absence of soft segments in AI aggregates (called globules). These aggregates are in the order of a few micrometers in size. The composition of the matrix and the AII aggregates (spherulites) was comparable.
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Xiaowei Jiang Yao Wang Wangqing Zhang Peiwen Zheng Linqi Shi 《Macromolecular rapid communications》2006,27(21):1833-1837
Summary: Raspberry‐like aggregates containing secondary nanospheres were studied. The formation of raspberry‐like aggregates was due to complexation between core‐shell microspheres and core‐corona micelles. The core‐shell microspheres were synthesized with soap‐free polymerization of styrene and methyl acrylic acid, which included carboxyl groups in the periphery. The micelles were self‐assembled by polystyrene‐block‐poly(4‐vinylpyridine), which contained pyridine groups in the corona. The driven force to form raspberry‐like aggregates was due to the affinity between the carboxyl and pyridine groups. The morphology of the raspberry‐like aggregates could be tuned by changing the ratio of the microspheres to micelles. IR measurements suggested that the raspberry‐like aggregates were like zwitterions.
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Weijie Lin Lorenz T. Biegler Annette M. Jacobson 《Macromolecular theory and simulations》2011,20(2):146-165
A comprehensive kinetic model is developed for a semi‐interpenetrating polymer network (SIPN) process, which involves simultaneous crosslinking, grafting, and degradation. Computational expense has been reduced considerably through a new component decomposition strategy, where a continuous variable approximation and a fixed pivot technique are applied for modeling each component. The inter‐polymer formulation is then reconstructed by a statistical approach. Based on the kinetic parameters obtained from the literature and a series of experiments, the model provides consistent agreement for gel fraction, joint molecular weight distribution (MWD) and polymer composition predicted in the studied cases, showing promising capability for the SIPN industrial application as well as for other polymer composite systems.
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Carlos Peniche Mar Fernndez Alberto Gallardo Antonio Lpez‐Bravo Julio San Romn 《Macromolecular bioscience》2003,3(10):540-545
Porous microspheres have been prepared by suspension free radical polymerization of acrylic acid (AA) in the presence of chitosan (CHI). The microspheres were characterized by FTIR and environmental SEM. The PAA content of the microspheres was estimated to be in the range 45–50 wt.‐%. The swelling degree of these particles is almost constant in the range 2 < pH < 5, but it increases considerably as the pH is raised from 5 to 10. The release profiles of microspheres loaded with meclofenamic acid (MF) were determined at pH 2, 7.4, and 10. The in vitro release of MF at different pHs was modulated by the solubility of the drug. These microcapsules are biodegradable and presented good biocompatibility and biodegradability during in vivo experiments.
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Nadezda G. Balabushevich Gleb B. Sukhorukov Natalia I. Larionova 《Macromolecular rapid communications》2005,26(14):1168-1172
Summary: Polyelectrolyte multilayer microspheres were prepared by alternating adsorption of dextran sulfate and protamine on melamine formaldehyde cores followed by the partial decomposition of the core. Peroxidase and glucose oxidase were immobilized in the prepared microspheres. Retention of enzymatic activity of the peroxidase/glucose oxidase system incorporated into the microspheres was demonstrated. Applicability of the bienzyme system immobilized in the microspheres for kinetic glucose assay was shown.
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Victoria L. Workman Stephen B. Dunnett Peter Kille Daniel D. Palmer 《Macromolecular rapid communications》2008,29(2):165-170
We report the use of a PTFE‐based microfluidic device for the encapsulation of living, therapeutically‐active cells within monodisperse alginate microspheres. We present a novel microfluidic platform and a flexible experimental method for the production of alginate microspheres. Cell lines HEK293, U‐2 OS and PC12 were separately encapsulated using this method, with minimal loss of cell viability.
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Summary: Ethylene and 10‐undecen‐1‐ol have been successfully copolymerized by an organically modified montmorillonite (OMMT)‐intercalated metallocene catalyst, Et[Ind]2ZrCl2, activated by methylaluminoxane (MAO). The obtained hydroxy‐functionalized polyethylene (PE‐OH)/OMMT nanocomposites exhibit enhanced structural stability as compared with the neat PE‐based ones, with no significant collapse of the nanocomposite structure being detected by WAXD examination after high‐temperature processing. The simultaneous polyolefin functionalization provides an effective and convenient solution to stabilize the PE/MMT nanocomposite structure formed by in‐situ polymerization.
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Summary: A simple sonochemical approach has been successfully developed to deposit poorly dissolved phthalocyanine dyes onto the surface of a highly‐ordered mesoporous nanostructured TiO2 thin film. The aggregation‐free phthalocyanines are effectively encapsulated and stabilized in the nanopore arrays of the zeolite‐like mesoporous nanocrystalline TiO2 thin film. Highly dispersed dye∥TiO2 heterojunction arrays with a large contact area can be obtained by using this interesting approach.