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2,5‐Bis(chloromethyl)‐1,3,4‐oxadiazole was synthesized and dehydrohalogenation of this model compound was investigated under various base conditions. The formation of an intermediate with quinodimethane‐type structure is suggested for reaction in EtONa/EtOH. Polymerization of this intermediate proceeds via an anionic mechanism to form poly(1,3,4‐oxadiazole‐2,5‐diyl‐1,2‐vinylene). Polymerization at a toluene/water interface results in shorter polymerization times, milder conditions, higher molecular weights, higher yields and fewer defects in the polymer as compared to the corresponding polycondensation route.
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Summary: Amphiphilic graft polyphosphazenes (EtTrp/PNIPAm‐PPP) with different mole ratios of hydrophobic groups to hydrophilic segments were synthesized by ring‐opening polymerization and subsequent substitution reactions. The self‐assembly behavior of these graft copolymers was studied in detail by TEM, SEM, CLSM, and AFM. Depending on the copolymer composition and common organic solvent employed in dialysis process, supramolecular aggregates ranging from network, nanospheres, high‐genus particles to macrophage‐like aggregates were produced with graft copolymers.
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Per B. Zetterlund Hirotomo Yamazoe Bunichiro Yamada 《Macromolecular rapid communications》2003,24(2):197-201
Detection of the adduct radical by ESR spectroscopy and after‐effect ESR measurements of the adduct radical concentrations in the photosensitized polymerization of styrene (St) in the presence of dimers of α‐methylstyrene (MSD) and methyl methacrylate have revealed that the dominant mechanism of adduct radical loss changes from bimolecular termination to fragmentation as the temperature is increased beyond 90 °C for St/MSD.
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Weipeng Lv Shuoqi Liu Xiaobin Fan Shulan Wang Guoliang Zhang Fengbao Zhang 《Macromolecular rapid communications》2010,31(5):454-458
A dextran‐based dual‐sensitive polymer is employed to endow gold nanoparticles with stability and pH‐ and temperature‐sensitivity. The dual‐sensitive polymer is prepared by RAFT polymerization of N‐isopropylacrylamide from trithiocarbonate groups linked to dextran and succinoylation of dextran after polymerization. The functionalized nanoparticles show excellent stability under various conditions and can be stored in powder‐form. UV and DLS measurements confirm that the temperature‐induced optical changes and aggregation behaviors of the particles are strongly dependent on pH.
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Summary: Tetraaniline‐block‐poly(L ‐lactide) diblock oligomers are synthesized via ring‐opening polymerization. The diblock oligomers cast from an L ‐lactide selective solvent (chloroform) show spherical aggregates for the leucoemeraldine state, and ring‐like structures that are composed of much smaller spherical aggregates for the emeraldine state. The formation mechanisms of the two different surface morphologies are discussed in detail.
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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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Summary: The ring‐opening polymerizations of 2‐phenyl‐5,6‐dihydro‐4H‐1,3‐oxazine (PhOZI) with methyl tosylate (MeOTs) and butyl iodide (BuI) as initiators were performed in refluxing butyronitrile. Reaction kinetics under microwave irradiation was compared with conventional oil bath heating. The polymerization rates, under microwave irradiation, showed an acceleration by a factor of 1.8 (independently from the used initiator). The investigation of the thermal properties of the obtained poly(N‐benzoyl‐trimethyleneimine) showed the influence of molecular weight and end‐groups on the glass transition temperature.
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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.
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Shu‐Juan Liu Wen‐Juan Xu Ting‐Chun Ma Qiang Zhao Qu‐Li Fan Qi‐Dan Ling Wei Huang 《Macromolecular rapid communications》2010,31(7):629-633
The effects of temperature and solvent on the β‐phase formation and energy transfer in an Ir(III) complex‐containing polyfluorene were investigated. Efficient energy transfer from polyfluorenes host to Ir complexes guest can be realized at low temperature. The formation of β‐phase was observed both in THF solution at low temperature and as suspended nano‐particles at room temperature. In addition, phosphorescent polymer nanoparticles were prepared successfully and exhibited efficient phosphorescent emission.
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Richard Hoogenboom Renzo M. Paulus ke Pilotti Ulrich S. Schubert 《Macromolecular rapid communications》2006,27(18):1556-1560
Summary: The use of microwave heating in polymer science is a rapidly growing field of research leading to faster and cleaner polymerization procedures. However, the majority of the investigations are performed at small scales (≈1 mL), which is far away from potential commercial applications of microwave‐assisted polymerizations. In addition, it has been shown in organic chemistry that microwave‐assisted reaction protocols can be directly scaled without the need for process optimization. In this contribution, we have investigated the direct scaling of microwave‐assisted polymerization procedures under pressure conditions using the cationic ring‐opening polymerization of 2‐ethyl‐2‐oxazoline as the model system. This polymerization was performed at scales ranging from 4.0 mmol (1 mL) to 1.0 mol (250 mL) in different microwave synthesizers covering both monomode and multimode devices.
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Helmut Schlaad Christina Diehl Anja Gress Matthias Meyer A. Levent Demirel Yusuf Nur Annabelle Bertin 《Macromolecular rapid communications》2010,31(6):511-525
Poly(2‐alkyl‐2‐oxazoline)s can be regarded as pseudo‐peptides or bioinspired polymers, which are available through living/controlled cationic polymerization and polymer (“click”) modification procedures. Materials and solution properties may be adjusted via the nature of the side chain (hydrophilic‐hydrophobic, chiral, bio‐functional, etc.), opening the way to stimulus‐responsive materials and complex colloidal structures in aqueous environments. Herein, we give an overview over the macromolecular engineering of polyoxazolines, including the synthesis of biohybrids, and the “smart”/bioinspired aggregation behavior in solution.
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Highly efficient and well‐controlled ambient temperature reversible addition–fragmentation chain transfer (RAFT) polymerization is readily carried out under environmentally friendly mild solar radiation. This discovery has significantly extended studies from man‐made separated‐spectroscopic‐emission UV‐vis radiation (Macromolecules 2006 , 39, 3770) to natural continuous‐spectroscopic‐emission solar radiation for ambient temperature RAFT polymerization.
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Tsutomu Yokozawa Ryosuke Suzuki Masataka Nojima Yoshihiro Ohta Akihiro Yokoyama 《Macromolecular rapid communications》2011,32(11):801-806
tBu3 PPd(Ph)Br ( 1 )‐catalyzed Suzuki‐Miyaura coupling polymerization of 2‐(4‐hexyl‐5‐iodo‐2‐thienyl)‐4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolane ( 2 ) was investigated. Monomer 2 was polymerized with 1 at 0 °C in the presence of CsF and 18‐crown‐6 in THF containing a small amount of water to yield P3HT with a narrow molecular weight distribution and almost perfect head‐to‐tail regioregularity. The values increased up to 11 400 g · mol−1 in proportion to the feed ratio of 2 to 1 . The MALDI‐TOF mass spectra showed that P3HT with moderate molecular weight uniformly had a phenyl group at one end and a hydrogen atom at the other, indicating involvement of a catalyst‐transfer mechanism. Successive 1 ‐catalyzed polymerization of fluorene monomer 3 and then 2 yielded a well‐defined block copolymer of polyfluorene and P3HT.
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Jan P. Robert Hiroshi Uyama Shiro Kobayashi Rainer Jordan Oskar Nuyken 《Macromolecular rapid communications》2003,24(2):185-189
The polymerization behavior of phenolic azosulfonates and triazene by means of enzymatic polymerization using horseradish peroxidase was studied. While for the latter one, only oligomerization was observed, sodium 4‐hydroxybenzenediazosulfonate was successfully homopolymerized. The obtained polymer had an average molecular weight of M n = 3 000 with a polydispersity index of 1.51. This is the first example of a homopolymer bearing an azosulfonate function in every monomer unit.
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Chakravarthy S. Gudipati Maureen B. H. Tan Hazrat Hussain Ye Liu Chaobin He Thomas P. Davis 《Macromolecular rapid communications》2008,29(23):1902-1907
Poly(glycidyl methacrylate) (PGMA) was synthesized by the RAFT method in the presence of 2‐cyanoprop‐2‐yl dithiobenzoate (CPDB) chain transfer agent using different [GMA]/[CPDB] molar ratios. The living radical polymerization resulted in controlled molecular weights and narrow polydispersity indices (PDI) of ≈1.1. The polymerization of pentafluorostyrene (PFS) with PGMA as the macro‐RAFT agent yielded narrow PDIs of ≤1.2 at 60 °C and ≤1.5 at 80 °C. The epoxy groups of the PGMA block were hydrolyzed to obtain novel amphiphilic copolymer, poly(glyceryl methacrylate)‐block‐poly(pentafluorostyrene) [PGMA(OH)‐b‐PPFS]. The PGMA epoxy group hydrolysis was confirmed by 1H NMR and FTIR spectroscopy. DSC investigation revealed that the PGMA‐b‐PPFS polymer was amorphous while the PGMA(OH)‐b‐PPFS displayed a high degree of crystallinity.