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1.
An ultraviolet (UV)‐cleavable bottlebrush polymer is synthesized using the “grafting‐onto” strategy by combining living radical polymerization and copper‐catalyzed azide‐alkyne cycloaddition (CuAAC). In this approach, reversible addition‐fragmentation chain transfer polymerization is used to prepare a poly(methylacrylate) backbone with azide side groups, while atom transfer radical polymerization is employed to prepare polystyrene (PS) side chains end‐functionalized with o‐nitrobenzyl (UV‐cleavable) propargyl groups. CuAAC is then used to graft PS side chains onto the polymer backbone, producing the corresponding bottlebrush polymers with UV‐cleavable PS side chains. The formation of the bottlebrush polymer is characterized by 1H nuclear magnetic resonance spectroscopy, gel permeation chromatography (GPC), and Fourier transform infrared spectroscopy. The cleavage behavior of the bottlebrush polymer is monitored in tetrahydrofuran solution under UV irradiation by GPC and viscosity measurements.

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2.
采用表面引发的原子转移自由基聚合法(ATRP)在聚偏二氟乙烯(PVDF)表面制备结构可控的聚甲基丙烯酸甲酯刷。通过碱处理和紫外光照溴代的方法,将ATRP引入到PVDF表面; 然后采用ATRP法将甲基丙烯酸甲酯接枝到溴代的PVDF表面。采用傅里叶变换红外光谱和X-射线光电子能谱对改性前后PVDF表面的结构进行了表征。结果表明甲基丙烯酸甲酯成功地接枝到了PVDF表面。  相似文献   

3.
A microphase‐separated, amphiphilic graft copolymer consisting of a poly (vinyl chloride) (PVC) backbone and poly(oxyethylene methacrylate) (POEM) side chains, (PVC‐g‐POEM at 62:38 wt %) was synthesized via atom transfer radical polymerization (ATRP). Nuclear magnetic resonance (1H NMR), FTIR spectroscopy, and transmission electron microscopy (TEM) clearly revealed that the “grafting from” method using ATRP was successful and that the graft copolymer molecularly self‐assembled into discrete nanophase domains of continuous PVC and isolated POEM regions. The self‐assembled graft copolymer film was used to template the growth of silver nanoparticles in solid state by introducing a AgCF3SO3 precursor and a UV irradiation process. The in situ formation of silver nanoparticles in the graft copolymer template film was confirmed by TEM, UV–visible spectroscopy, and wide angle X‐ray scattering. FTIR spectroscopy and X‐ray photoelectron spectroscopy also demonstrated the selective incorporation and in situ formation of silver nanoparticles within the hydrophilic POEM domains, presumably due to strong interactions between the silver and the ether oxygen in POEM. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3911–3918, 2008  相似文献   

4.
Novel water‐soluble triply‐responsive homopolymers of N,N‐dimethylaminoethyl methacrylate (DMAEMA) containing an azobenzene moiety as the terminal group were synthesized by atom transfer radical polymerization (ATRP) technique. The ATRP process of DMAEMA was initiated by an azobenzene derivative substituted with a 2‐bromoisobutyryl group (Azo‐Br) in the presence of CuCl/Me6TREN in 1,4‐dioxane as a catalyst system. The molecular weights and their polydispersities of the resulting homopolymers (Azo‐PDMAEMA) were characterized by gel permeation chromatography (GPC). The homopolymers are soluble in aqueous solution and exhibit a lower critical solution temperature (LCST) that alternated reversibly in response to Ph and photoisomerization of the terminal azobenzene moiety. It was found that the LCST increased as pH decreased in the range of testing. Under UV light irradiation, the trans‐to‐cis photoisomerization of the azobenzene moiety resulted in a higher LCST, whereas it recovered under visible light irradiation. This kind of polymers should be particularly interesting for a variety of potential applications in some promising areas, such as drug controlled‐releasing carriers and intelligent materials because of the multistimuli responsive property. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2564–2570, 2010  相似文献   

5.
Novel porous polymer monoliths grafted with poly{oligo[(ethylene glycol) methacrylate]‐co‐glycidyl methacrylate} brushes were fabricated via two‐step atom‐transfer radical polymerization and used as a trypsin‐based reactor in a continuous flow system. This is the first time that atom‐transfer radical polymerization technique was utilized to design and construct polymer monolith bioreactor. The prepared monoliths possessed excellent permeability, providing fast mass transfer for enzymatic reaction. More importantly, surface properties, which were modulated via surface‐initiated atom‐transfer radical polymerization, were found to have a great effect on bioreactor activities based on Michaelis–Menten studies. Furthermore, three model proteins were digested by the monolith bioreactor to a larger degree within dramatically reduced time (50 s), about 900 times faster than that by free trypsin (12 h). The proposed method provided a platform to prepare porous monoliths with desired surface properties for immobilizing various enzymes.  相似文献   

6.
The cyclic amphiphilic polymers with azobenzene in main chain, cyclic azobenzene tetraethylene glycol polystyrene (cyclic‐Azo‐TEG‐PS) with different molecular weights, were successfully synthesized by combining atom transfer radical polymerization (ATRP) and Cu (I)‐catalyzed azide/alkyne cycloaddition (CuAAC). Gel permeation chromatography (GPC), proton nuclear resonance (1H NMR), Fourier transform‐infrared (FT‐IR), and matrix‐assisted laser desorption/ionization time of flight (MALDI‐TOF) mass spectrometry were used to prove the complete conversion from linear polymers to cyclic ones. The thermal properties and photoisomerization behaviors of obtained cyclic polymers have been investigated by comparison with the linear analogues. The cyclic polymer displayed a higher glass transition temperature compared with the linear one, measured by differential scanning calorimetry (DSC). It was found that the trans‐to‐cis and cis‐to‐trans isomerization of cyclic polymers was both slower than that of their respective linear counterparts upon irradiation by UV/visible light. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1834–1841  相似文献   

7.
The preparation of a series of novel homopolymers and copolymers containing bisazobenzene chromophores with side‐on structure in the side chains via atom transfer radical polymerization (ATRP) were presented. UV–vis spectra of the thin films of these polymers under irradiation of 488 nm Ar+ laser suggested that the photoisomerization of the bisazobenzene chromophores happened mainly on one of the two azo groups in the bisazobenzene chromophores with similar probability due to their side‐on structure. Good photoalignment behaviors of these polymers were proved by photoinduced birefringence measurements because side‐on structure permitted the two azo groups in the bisazobenzene chromophores both participated in the trans–cis–trans photoisomerization cycles equally to induce the whole chromophore reorientation. Furthermore, the reorientation axis located at the middle of chromophore decreased the sweep volume during photoalignment. The impetus for this study was to evaluate the photoisomerization and photoalignment process of side‐on bisazobenzene‐containing polymers and to find possible applications in the photosensitive devices. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3460–3472, 2007  相似文献   

8.
A novel monomer, ethyl 4‐[4‐(11‐methacryloyloxyundecyloxy)phenyl azobenzoyl‐oxyl] benzoate, containing a photoisomerizable N?N group was synthesized. The monomer was further diblock copolymerized with methyl methacrylate. Amphiphilic diblock copolymer poly(methyl methacrylate‐block‐ethyl 4‐[4‐(11‐methacryloyloxyundecyloxy)phenyl azobenzoyl‐oxyl] benzoate ( PMMA ‐ b ‐ PAzoMA ) was synthesized using atom transfer radical polymerization. The reverse micelles with spherical construction were obtained with 2 wt % of the diblock copolymer in a THF/H2O mixture of 1:2. Under alternating UV and visible light illumination, reversible changes in micellar structure between sphere and rod‐like particles took place as a result of the reversible E‐Z photoisomerization of azobenzene segments in PMMA ‐ b ‐ PAzoMA . Microphase separation of the amphiphilic diblock copolymer in thin films was achieved through thermal and solvent aligning methods. The microphases of the annealed thin films were investigated using atom force microscopy topology and scanning electron microscopy analyses. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1142–1148, 2010  相似文献   

9.

Three kinds of photoresponsive copolymers with azobenzene side chains were synthesized by radical polymerization of N‐4‐phenylazophenylacrylamide (PAPA) with N‐isopropylacrylamide (NIPAM), N,N‐diethylacrylamide (DEAM) or N,N‐dimethylacrylamide (DMAM) respectively. Their structures were characterized by FT‐IR, 1H‐NMR and UV/Vis spectroscopy. Their reversible photoresponses were studied with or without α‐cyclodextrin (α‐CD), which showed that both the copolymers and their inclusion complexes with α‐CD underwent rapid photoisomerization. The lower critical solution temperature (LCST) of the copolymers and their inclusion complexes with α‐CD were investigated by cloud point measurement, which showed that the LCST of three kinds of copolymers increased largely after adding α‐CD. After UV irradiation on the solutions of copolymers and their inclusion complexes, the LCST of the copolymers increased slightly with the absence of α‐CD, while decreased largely with the presence of α‐CD. Furthermore, the LCST reverted to its originality after visible light irradiation. This change of LCST could be reversibly controlled by UV and visible light irradiation alternately. In particular, in the copolymer of PAPA and DMAM, the reversible water solubility of the inclusion complexes could be triggered by alternating UV and visible light irradiation.  相似文献   

10.
Polymer brushes decorated reduced GO (rGO) with advanced applications have been prepared by bioinspired polydopamine (PDA) chemistry integrated with activators regenerated by electron transfer atom transfer radical polymerization (ARGET‐ATRP) technique. First, rGO/PDA was obtained by the process for graphene oxide (GO) coated with a homogeneous bio‐adhesive PDA layer. Then the initiator 2‐bromoisobutyryl bromide (BIBB) was immobilized on the surface of PDA functionalized rGO. Finally, rGO/PDA‐Br was polymerized with N, N‐diethylaminoethyl methacrylate (DEAEMA) and glycidyl methacrylate (GMA) to obtain rGO/PDA‐g‐polymer brushes by ARGET‐ATRP process. The prepared rGO/PDA‐g‐PGMA brush would be subjected to further functionalization with ethylenediamine (EDA), which would impart the obtained products (rGO/PDA‐g‐PGMA‐NH2) with good adsorption ability toward cationic dyes. The chemical structures and morphologies of the functionalized GO products have been characterized in detail by Fourier transform infrared spectroscopy (FTIR), X‐ray photoelectron spectroscopy (XPS), Raman spectroscopy, thermal gravimetric analysis (TGA), scanning electron microscope (SEM), transmission electron microscope(TEM), and atomic force microscopy (AFM). The distinctive pH‐responsive character of rGO/PDA‐g‐PDEAEMA and adsorption ability of rGO/PDA‐g‐PGMA‐NH2 for cationic dyes have been explored by UV–vis spectrophotometer. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 689–698  相似文献   

11.
Activation‐free copolymeric films possessing high selectivity to target proteins and low biofouling background are prepared via controlled radical polymerization. The copolymeric films are generated by surface‐initiated activators regenerated by electron transfer atom transfer radical polymerization (SI‐ARGET ATRP) of N‐acryloxysuccinimide (NAS) and oligo(ethylene glycol) methyl ether methacrylate (OEGMEMA) by controlling the molar feed ratio of the two monomers. The formation of copolymeric films is characterized by ellipsometry, contact angle goniometry, FTIR spectroscopy, and X‐ray photoelectron spectroscopy. The prepared copolymeric films are biotinylated without an activation step. Biotin–streptavidin association is employed as a model system to investigate both selective binding and the relevant signal‐to‐noise (S/N) ratio. When the molar feed ratio of NAS and OEGMEMA is 2:8, the copolymeric film is optimized to give the highest S/N ratio (339.8) according to surface plasmon resonance studies. The highly selective bioconjugation is used to generate micropatterns of rhodamine‐conjugated streptavidin on the copolymeric film. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 329–337  相似文献   

12.
A new thermally switchable molecularly imprinted monolith for the selective capture and release of proteins has been designed. First, a generic poly(glycidyl methacrylate‐co‐ethylene dimethacrylate) monolith reacted with ethylenediamine followed by functionalization with 2‐bromoisobutyryl bromide to introduce the initiator for atom transfer radical polymerization. Subsequently, a protein‐imprinted poly(N‐isopropylacrylamide) layer was grafted onto the surface of the monolithic matrix by atom transfer radical polymerization. Scanning electron microscopy and energy‐dispersive X‐ray spectroscopy of the cross‐sections of imprinted monoliths confirmed the formation of dense poly(N‐isopropylacrylamide) brushes on the pore surface. The imprinted monolith exhibited high specificity and selectivity toward its template protein myoglobin over competing proteins and a remarkably large maximum adsorption capacity of 1641 mg/g. Moreover, this “smart” imprinted monolith featured thermally responsive characteristics that enabled selective capture and easy release of proteins triggered only by change in temperature with water as the mobile phase and avoided use of stronger organic solvents or change in ionic strength and pH.  相似文献   

13.
In this study, random terpolymers of methoxy poly(ethylene glycol)‐poly(sodium styrene sulfonate‐co‐methyl methacrylate) (MPEG‐P(SSNa‐co‐MMA)) integrated with antifouling and anticoagulant properties were synthesized by atom transfer radical polymerization (ATRP) for the first time and confirmed by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and gel permeation chromatography (GPC). The terpolymers with desired antifouling and anticoagulant segments were then used as amphiphilic additives to modify polyethersulfone membranes by an engineering blended approach. Water contact angle (WCA) results indicated that the surface hydrophilicity of the modified membranes enhanced. Protein ultrafiltration experiments showed that the antifouling ability of the modified membranes increased. In addition, the modified membranes showed decreased protein adsorption (bovine serum albumin, BSA), suppressed platelet adhesion, and prolonged activated partial thromboplastin time (APTT). Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

14.
A novel ABA triblock copolymer comprising double‐bond‐containing poly(phenoxyallene) (PPOA) and polystyrene (PS) segments was synthesized by sequential conventional free radical polymerization and atom transfer radical polymerization (ATRP) via the site transformation strategy. A new bifunctional initiator containing azo and Br‐containing ATRP initiating groups was prepared using 2‐bromopropionyl chloride, hydroquinone, and 4,4′‐azobis(4‐cyanopentanoic acid) as starting materials. Conventional free radical homopolymerization of phenoxyallene with cumulated double bond was performed in toluene to provide a polyallene‐based macroinitiator bearing ATRP initiating groups at both ends, which is stable under UV irradiation and free radical circumstances. PS‐b‐PPOA‐b‐PS triblock copolymer was then obtained by bulk ATRP of styrene initiated by PPOA‐based macroinitiator. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 1366–1372  相似文献   

15.
Hydrophilic/CO2‐philic poly(ethylene oxide)‐b‐poly(1,1,2,2‐tetrahydroperfluorodecyl acrylate) block copolymers were synthesized via reversible addition–fragmentation chain transfer (RAFT) polymerization, iodine transfer polymerization (ITP), and atom transfer radical polymerization (ATRP) in the presence of either degenerative transfer agents or a macroinitiator based on poly(ethylene oxide). In this work, both RAFT and ATRP showed higher efficiency than ITP for the preparation of the expected copolymers. More detailed research was carried out on RAFT, and the living character of the polymerization was confirmed by an ultraviolet (UV) analysis of the ? SC(S)Ph or ? SC(S)S? C12H25 end groups in the polymer chains. The quantitative UV analysis of the copolymers indicated a number‐average molecular weight in good agreement with the value determined by 1H NMR analysis. The properties of the macromolecular surfactants were investigated through the determination of the cloud points in neat liquid and supercritical CO2 and through the formation of water‐in‐CO2 emulsions. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2405–2415, 2004  相似文献   

16.
The photodegradation of an amine‐cured epoxy coating after exposure to accelerated UV‐340 and UV‐313 irradiation was investigated with an atomic‐level technique, positron annihilation spectroscopy (PAS), which detected and characterized the free volumes and defects as a function of the depth. Significant changes in the subnanometer defect parameters S and W were observed as a function of the exposure time near the surface. This was interpreted as due to a loss of the free volume and hole fraction resulting from photodegradation. A dead layer near the surface, resulting from UV irradiation from the surface up to a thickness of 0.4 μm, at which there was nearly no positronium formation, was observed. Correlations between physical defects from PAS in terms of the free volumes and chemical defects from electron spin resonance spectroscopy in terms of free radicals and chemical structural changes measured by ultraviolet–visible and Fourier transform infrared spectroscopy were established. A high sensitivity of PAS for detecting the early stage of degradation, on the order of hours for UV‐313 and on the order of days for UV‐340 irradiation, was observed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2441–2459, 2004  相似文献   

17.
A novel trifunctional iniferter with photoinduced and thermal chemical dissociation functional groups in one molecule, diethyl 2,3‐dicyano‐2,3‐di(pN,N‐diethyldithiocarbamylmethyl)phenylsuccinate (DDDCS), was successfully synthesized. The bulk polymerizations of styrene and methyl methacrylate initiated by DDDCS under UV‐light irradiation and heating, respectively, were studied. The polymerizations proceeded via a living polymerization process in both cases; that is, the conversion and molecular weight of the resulting polymer increased linearly with increased reaction time. The resulting polymers, containing α‐ and ω‐N,N‐diethyldithiocarbamyl end groups, served as macroiniferters for further block copolymerization. Electron paramagnetic resonance studies showed that DDDCS initiated as a photoiniferter under UV‐light irradiation by reversible C S‐bond dissociation and as a thermal iniferter under heating by reversible hexasubstituted C C‐bond dissociation. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2115–2120, 2000  相似文献   

18.
In order to examine competitive photoisomerization, a series of novel photochromic PtII molecules that contain both dithienylethene (DTE) and B(ppy)Mes2 units (ppy=2-phenylpyridine, Mes=mesityl) were successfully synthesized and fully structurally characterized. Their photochromic properties were examined by UV/Vis, emission and NMR spectroscopy. It was found that the DTE unit in all three compounds is the preferred photoisomerization site, exhibiting reversible photochromism with irradiation. The B(ppy)Mes2 unit does not undergo photoisomerization in these molecules, but likely enhances the photoisomerization quantum efficiency of the DTE moiety through the antenna effect. Extended irradiation with UV light leads to the rearrangement of the ring-closed isomers of DTE. TD-DFT computational studies indicate that the DTE photocyclization proceeds via a triplet pathway through an efficient energy transfer process.  相似文献   

19.
Two novel and well‐defined polymers, poly[6‐(5‐(diphenylamino)‐2‐((4‐methoxyphenyl)diazenyl)phenoxy)hexyl methacrylate] (PDMMA) and poly[6‐(4‐((3‐ethynylphenyl)diazenyl) phenoxy)hexyl methacrylate] (PDPMMA), which bear triphenylamine (TPA) incorporated to azobenzene either directly (PDMMA) or with an interval (PDPMMA) as pendant groups were successfully prepared via reversible addition‐fragmentation chain transfer polymerization technique. The electrochemical behaviors of PDPMMA and PDMMA were investigated by cyclic voltammograms (CV) measurement. The hole mobilities of the polymer films were determined by fitting the J‐V (current‐voltage) curve into the space‐charge‐limited current method. The influence of photoisomerization of the azobenzene moiety on the behaviors of fluorescence emission, CV and hole mobilities of these two polymers were studied. The fluorescent emission intensities of these two polymers in CH2Cl2 were increased by about 100 times after UV irradiation. The oxidation peak currents (IOX) of the PDMMA and PDPMMA in CH2Cl2 were increased after UV irradiation. The photoisomerization of the azobenzene moiety in PDMMA had significant effect on the electrochemical behavior, compared with that in PDPMMA. The changes of the hole mobility before and after UV irradiation were very small for both polymers. The HOMO energies (EHOMO, HOMO: the highest occupied molecular orbital) of side chain moieties of TPA incorporated with cis‐isomer and trans‐isomer of azobenzene in PDMMA and PDPMMA were obtained by theoretical calculation, which are basically consistent with the experimental results. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012  相似文献   

20.
Biomaterials generally suffer from rapid nonspecific protein adsorption, which initiates many deleterious host responses, and complex chemistries that are employed to facilitate cellular interactions. A chemical approach that, based upon current literature, combines a nonfouling architecture with a biomemtic cell‐adhesive end‐group, is presented. Namely, surface‐initiated polymerization of zwitterionic [poly (carboxybetaine methacrylamide)] brushes, with controlled charge densities and phosphonate head groups. Nitroxide mediated free radical polymerization (NMFRP) was employed for various reasons: reduces presence of potentially cytotoxic organometallic catalysts common in atom transfer radical polymerization (ATRP); and it allows a phosphonate end‐group instead of the common brominated end‐group. Thermally oxidized silicon wafers were covalently functionalized with diethyl‐(1‐(N‐(1‐(3‐(trimethoxysilyl)propylcarbamoyl)ethoxy)‐N‐tert‐butylamino)ethyl)phosphonate. NMFRP was used to graft zwitterionic carboxybetaine methacrylamide monomers of varying inter‐charge separation. The resulting thin films were characterized using Attenuated Total Reflectance‐Fourier Transform Infrared (ATR‐FTIR) and X‐ray photoelectron (XPS) spectroscopy, ellipsometry, water contact angle analysis, and thermo gravimetric analysis (TGA). The effect of spacer group on the surface charge density was determined using zeta potential techniques. It is thought that this stratagem will facilitate the ability to tailor systematically both the interior and terminal polymer properties, providing a platform for further understanding how these conditions affect protein adsorption as well as cell‐surface interactions. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011  相似文献   

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