共查询到20条相似文献,搜索用时 781 毫秒
1.
Anthony J. Convertine Brad S. Lokitz Andrew B. Lowe Charles W. Scales Leslie J. Myrick Charles L. McCormick 《Macromolecular rapid communications》2005,26(10):791-795
Summary: The first example of a room temperature reversible addition‐fragmentation chain transfer polymerization conducted directly in aqueous media is detailed. Under these conditions acrylamide and N,N‐dimethylacrylamide may be polymerized in a controlled fashion to near quantitative conversions employing a difunctional trithiocarbonate chain transfer agent (CTA). Hydrolysis studies conducted at pH 5.5 suggest that the CTA is stable up to approximately 50 °C.
2.
Kazuki Miyake Per B. Zetterlund Bunichiro Yamada 《Macromolecular rapid communications》2004,25(22):1905-1911
Summary: Experimental and modeling studies of addition–fragmentation chain transfer (AFCT) during radical polymerization of methyl methacrylate in the presence of poly(methyl methacrylate) macromonomer with 2‐carbomethoxy‐2‐propenyl ω‐ends (PMMA‐CO2Me) at 60 °C are reported. The results revealed that AFCT involving PMMA‐CO2Me formed in situ during methyl methacrylate polymerization has a negligible effect on the molecular weight distribution.
3.
Summary: A water‐soluble gold nanoparticle aggregate 2 was prepared by chloroauric acid and a polypseudorotaxane 1 of mono‐6‐thio‐β‐cyclodextrin with poly(propylene glycol) bis(2‐aminopropyl ether) ( ≈ 2 000) in the presence of sodium borohydride in N,N‐dimethylformamide (DMF) solution. The investigative results indicated that the gold nanoparticle aggregate 2 might act as an efficient DNA‐cleavage reagent.
4.
Per B. Zetterlund Md. Nur Alam Hideto Minami Masayoshi Okubo 《Macromolecular rapid communications》2005,26(12):955-960
Summary: The nitroxide‐mediated controlled/living free radical copolymerization of styrene and divinylbenzene using a polystyrene‐TEMPO macroinitiator in aqueous miniemulsion and in bulk have been investigated. The crosslink densities were estimated based on the content of pendant vinyl groups as determined by 1H NMR. Considerably lower crosslink densities were revealed in the miniemulsion than in the corresponding bulk system. The rate of polymerization in the miniemulsion increased with decreasing particle size, and was significantly higher than in bulk.
5.
Montserrat Vera Alfonso Rodríguez‐Galn Jordi Puiggalí 《Macromolecular rapid communications》2004,25(7):812-817
Summary: A new method for the preparation of poly(ester amide)s derived from glycolic acid units has been developed. Glycolic acid units can be incorporated with a high yield into a nylon‐n or a nylon‐n,m. The synthesis is based on a final thermal polycondensation with the formation of a metal halide salt as a driving force. New poly(ester amide)s have high molecular weights, good mechanical behaviour, and variable thermal properties, giving rise to a group of materials with potential interest as biodegradable materials in applications like surgical sutures.
6.
Ning Zhao Jian Xu Qiongdan Xie Lihui Weng Xinglin Guo Xiaoli Zhang Lianghe Shi 《Macromolecular rapid communications》2005,26(13):1075-1080
Summary: A superhydrophobic coating was facilely fabricated in one step by casting bisphenol A polycarbonate (PC) solution under moisture. Vapor‐induced phase separation occurred during the solidifying process and a rough surface with a micro‐nano‐binary structure (MNBS) similar to the microstructure shown on lotus leaf was formed.
7.
Summary: This paper reports the microwave mediated direct synthesis of N‐phenylmaleimide ( 3 ) from maleic anhydride ( 1 ) and aniline ( 2 ) by using microwave irradiation. Good yields and very short reaction times were the main aspects of the method. The reaction conditions and kinetics of this process were investigated. Microwave irradiation in a boiling solvent showed the existence of a significant specific microwave effect. The microwave homopolymerization of 3 in bulk using 2,2′‐azoisobutyronitrile (AIBN) as a free radical initiator was also carried out.
8.
Lydie Viau Michael Even Olivier Maury David M. Haddleton Hubert Le Bozec 《Macromolecular rapid communications》2003,24(10):630-635
The synthesis of new star‐shaped polymers, prepared by atom transfer radical polymerization of methyl methacrylate with tris(dialkylaminostyryl‐2,2′‐bipyridine) zinc(II) and iron(II) metalloinitiators, is reported. Their thermal and optical (absorption and emission) properties are discussed.
9.
Rate constants for long‐chain branch formation during ethylene polymerization with metallocene catalysts were estimated and compared to polymerization rate constants for long α‐olefins. Unexpectedly, these branching constants were found to be comparable to the reactivity ratios of much shorter α‐olefins. Micromixing effects or a parallel mechanism for long‐chain branch generation are proposed as possible explanations for this finding.
10.
Richard Hoogenboom Martin W. M. Fijten Christof Brndli Josef Schroer Ulrich S. Schubert 《Macromolecular rapid communications》2003,24(1):98-103
Sixteen parallel polymerization reactions of 2‐ethyl‐2‐oxazoline have been performed at different temperatures in an automated synthesizer that allowed individual heating of each reactor. During the reactions samples were taken automatically, which were characterized by means of both online GPC and offline GC, in order to optimize the reaction temperature and to determine the activation energy of the polymerization.
11.
Anatoly N. Nikitin Patrice Castignolles Bernadette Charleux Jean‐Pierre Vairon 《Macromolecular rapid communications》2003,24(13):778-782
Unusual difficulties are faced in the determination of propagation rate coefficients (kp) of alkyl acrylates by pulsed‐laser polymerization (PLP). When the backbiting is the predominant chain transfer event, the apparent kp of acrylates determined in PLP experiments for different frequencies should range between kp (propagation rate coefficient of the secondary radicals) at high frequency and k at low frequency. The k value could be expressed from kinetic parameters: , where kfp is the backbiting rate coefficient, kp2 is the propagation rate coefficient of mid‐chain radicals, and [M] is the monomer concentration.
12.
Gaojian Chen Xiulin Zhu Jian Zhu Zhenping Cheng 《Macromolecular rapid communications》2004,25(7):818-824
Summary: Plasma‐initiated controlled/living radical polymerization of methyl methacrylate (MMA) was carried out in the presence of 2‐cyanoprop‐2‐yl 1‐dithionaphthalate. Well‐defined poly(methyl methacrylate) (PMMA), with a narrow polydispersity, could be synthesized. The polymerization is proposed to occur via a RAFT mechanism. Chain‐extension reactions were also successfully carried out to obtain higher molecular weight PMMA and PMMA‐block‐PSt copolymer.
13.
Azadeh Samadi Scott M. Husson Yong Liu Igor Luzinov S. Michael Kilbey 《Macromolecular rapid communications》2005,26(23):1829-1834
Summary: This contribution describes the graft polymerization of polystyrene (PS) by atom transfer radical polymerization at 50, 60, and 75 °C. Thick PS brushes were grown from initiator‐functionalized PGMA layers on silicon, and constant growth rates provide indirect evidence that the polymerizations were controlled.
14.
Himabindu Nandivada Hsien‐Yeh Chen Joerg Lahann 《Macromolecular rapid communications》2005,26(22):1794-1799
Summary: The vapor‐based synthesis and characterization of a reactive polymer, poly[(4‐formyl‐p‐xylylene)‐co‐(p‐xylylene)] ( 1 ), have been reported. The reactive polymer coating enables the immobilization of oligosaccharides via the chemoselective aldehyde‐hydrazide coupling reaction.
15.
Jun Ma Zhong‐Zhen Yu Hsu‐Chiang Kuan Arovind Dasari Yiu‐Wing Mai 《Macromolecular rapid communications》2005,26(10):830-833
Summary: A new strategy was developed to prepare disorderly exfoliated nanocomposites, in which a soft siloxane surfactant with a weight‐average molecular weight ( ) of 1 900 was adopted to modify the clay. The modified clay slurry was then mixed with silicone rubber by hand, and exfoliation was achieved. The proposed mechanism thereof was verified by TEM and XRD. The physical entanglement of the soft siloxane surfactant plays a vital role in the diffusion and intercalation of the matrix molecules during the compounding of the slurry‐polymer mixture. This simple method is applicable to other silicone‐based materials reinforced by clay.
16.
Yue Cui Cheng Tao Suping Zheng Qiang He Sufen Ai Junbai Li 《Macromolecular rapid communications》2005,26(19):1552-1556
Summary: Thermosensitive polymer nanotubes can be fabricated within an aminopropylsilane‐modified porous anodic aluminum oxide membrane by surface‐initiated atom transfer radical polymerization (ATRP) followed by template removal. DSC experiments prove that the synthesized PNIPAM‐co‐MBAA copolymer nanotubes have a reversible thermosensitive behavior. The temperature‐induced changes in dimension and shape of the nanotubes were studied by AFM in real time in an aqueous environment. It indicates that the nanotubes undergo a shape alteration from an “ellipse” to “circular” shape in water upon heating to LCST or above.
17.
Takanobu Sanji Daisuke Sunaga Yasuhiro Muto Hideki Sakurai 《Macromolecular rapid communications》2003,24(4):340-343
A novel method is described for transforming an anionic polymerization process into a cationic polymerization process assisted by organosilyl groups. The reaction of the p‐tolyldimethylsilyl end group of polystyrene and trifluoromethanesulfonic acid produced a silyl triflate end group that served as a macroinitiator for the living cationic polymerization of isobutyl vinyl ether. The Si O linkage in the block copolymers underwent specific cleavage by reaction with tetrabutylammonium fluoride.
18.
Bo Zhu Yong He Naoki Asakawa Naoko Yoshie Haruo Nishida Yoshio Inoue 《Macromolecular rapid communications》2005,26(8):581-585
Summary: A new crystal morphology (δ form) of poly(3‐hydroxypropionate) (PHP) is found in cast and melt‐crystallized PHPs with low molecular weight, in which the PHP chains possibly adopt a 21 helix rather than the trans conformation found in the β or γ form. The fusion temperature‐ and the crystallization temperature‐dependent polymorphism are responsible for the dual morphologies and the unique growth kinetics of spherulites in the melt‐crystallized PHPs.
19.
Summary: A multistep synthetic procedure for preparing novel C60‐anchored two‐armed poly(tert‐butyl acrylate) was developed. First, two‐armed poly(tert‐butyl acrylate) bearing a malonate ester core with well‐controlled molecular weight was synthesized through atom transfer radical polymerization. The effective Bingel reaction between C60 and the well‐defined polymer was then carried out to yield C60‐anchored polymer. GPC, 1H NMR, and UV‐vis spectroscopy indicated that the C60‐anchored polymer was a monosubstituted and ‘closed’ 6,6‐ring‐bridged methanofullerene derivative.
20.
Summary: Self‐oscillating polymers and nano‐gel particles consisting of N‐isopropylacrylamide and the ruthenium catalyst of the Belousov‐Zhabotinsky reaction have been prepared. In order to clarify the crosslinking effect on the self‐oscillating behavior, the phase transition behaviors were investigated by measuring the transmittance and the fluorescence intensity of the polymer solution and the gel bead suspension. Cooperative effects due to crosslinking will play an important role for the design of nanoactuators.