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1.
Poly(methylphenylsiloxane)–poly(methyl methacrylate) graft copolymers (PSXE-g-PMMA) were prepared by condensation reaction of poly(methylphenylsiloxane)-containing epoxy resin (PSXE) with carboxyl-terminated poly(methyl methacrylate) (PMMA), and they were characterized by gel permeation chromatography (GPC), infrared (IR), and 29Si and 13C nuclear magnetic resonance (NMR). The microstructure of the PSXE-g-PMMA graft copolymer was investigated by proton spin–spin relaxation T2 measurements. The thermal stability and apparent activation energy for thermal degradation of these copolymers were studied by thermogravimetry and compared with unmodified PMMA. The incorporation of poly(methylphenylsiloxane) segments in graft copolymers improved thermal stability of PMMA and enhanced the activation energy for thermal degradation of PMMA. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2521–2530, 1998  相似文献   

2.
Oligo(N-vinyl-4,5,6,7-tetrahydroindole-co-butyl vinyl ethers) have been synthesized through free-radical cooligomerization with a yield of 84%. The copolymers are readily soluble in organic solvents (benzene, 1,4-dioxane, chloroform, and tetrahydrofuran), stable up to 380–400°C, and paramagnetic. (The concentration of paramagnetic centers is 1014 spin/g.) In addition, the copolymers exhibit the properties of organic semiconductors. (After being doped with iodine, σ = 1.1 × 10?7 S/cm.) The analysis of the 1H and 13C NMR spectra has shown that the oligomerization reaction is complicated by intramolecular cyclization involving carbon atoms located at the 2-position of pyrrole rings.  相似文献   

3.
A new 4-(N-methylpiperazine)-N-allyl-1,8-naphthalimide with intense yellow-green fluorescence has been synthesized. Then it has been copolymerized with styrene and methylmetacrylate. The photophysical characteristics of the fluorescent dye and its copolymers (poly(St-co-NI) and poly(MAA-co-NI)) have been determined viewing their sensor properties for protons and transition metal cations (Cu2+, Fe3+ and Zn2+). Fluorescence enhancement is the photophysical response of the 4-(N-methylpiperazine)-N-allyl-1,8-naphthalimide to the presence of metal cations and protons, while fluorescence quenching is observed for both copolymers.  相似文献   

4.
Organic–inorganic pentablock copolymers have been synthesized via atom transfer radical polymerization (ATRP) of styrene (St) and vinyl acetate (VAc) monomers at 60 °C using CuCl/N,N,N′,N″,N″-pentamethyldiethylenetriamine as a catalyst system initiated from boromoalkyl-terminated poly(dimethylsiloxane) (PDMS)/cyclodextrins macroinitiator (Br-PDMS/γ-CD). Br-PDMS-Br was reacted with γ-CD in different conditions with inclusion complexes being characterized through hydrogen nuclear magnetic resonance (1H NMR) and differential scanning calorimetry (DSC). Resulting Br-PDMS-Br/γ-CD inclusion complexes were taken as macroinitiators for ATRP of St and VAc. Well-defined poly(styrene)-b-poly(vinyl acetate)-b-poly(dimethylsiloxane/γ-cyclodextrin)-b-poly(vinyl acetate)-b-poly(styrene) (PSt-b-PVAc-b-PDMS/γ-CD-b-PVAc-b-PSt) pentablock copolymer was characterized by 1H NMR, gel permeation chromatograph (GPC) and DSC. There was a good agreement between the number-average molecular weight calculated from 1H NMR spectra and that of theoretically calculated. Pentablock copolymers consisting of Br-PDMS-Br/γ-CD inclusion complex as central blocks (inorganic block) and PVAc and PSt as terminal blocks were synthesized by this technique. PSt-b-PVAc-b-PDMS/γ-CD-b-PVAc-b-PSt pentablock copolymer can undergo a temperature-induced reversible transition upon heating of the copolymer complex from white complex at 22 °C to green complex in 55 °C which characterized with XRD and 1H NMR. XRD showed a change in crystallinity percent of St peak with changing the temperature which calculated by Origin75 software.  相似文献   

5.
Amphiphilic core–shell nanostructures containing 19F stable isotopic labels located regioselectively within the core domain were prepared by a combination of atom transfer radical polymerization (ATRP), supramolecular assembly, and condensation‐based crosslinking. Homopolymers and diblock copolymers containing 4‐fluorostyrene and methyl acrylate were prepared by ATRP, hydrolyzed, assembled into micelles, and converted into shell‐crosslinked nanoparticles (SCKs) by covalent stabilization of the acrylic acid residues in the shell. The ATRP‐based polymerizations, producing the homopolymers and diblock copolymers, were initiated by (1‐bromoethyl)benzene in the presence of CuBr metal and employed N,N,N,N,N″‐pentamethyldiethylenetriamine as the coordinating ligand for controlled polymerizations at 75–90 °C for 1–3 h. Number‐average molecular weights ranged from 2000 to 60,000 Da, and molecular weight distributions, generally less than 1.1 and 1.2, were achieved for the homopolymers and diblock copolymers, respectively. Methyl acrylate conversions as high as 70% were possible, without observable chain–chain coupling reactions or molecular weight distribution broadening, when bromoalkyl‐terminated poly(4‐fluorostyrene) was used as the macroinitiator. Poly(4‐fluorostyrene), incorporated as the second segment in the diblock copolymer synthesis, was initiated from a bromoalkyl‐terminated poly(methyl acrylate) macroinitiator. After hydrolysis of the poly(methyl acrylate) block segments, micelles were formed from the resulting amphiphilic block copolymers in aqueous solutions and were then stabilized by covalent intramicellar crosslinking throughout the poly(acrylic acid) shells to yield SCKs. The SCK nanostructures on solid substrates were visualized by atomic force microscopy and transmission electron microscopy. Dynamic light scattering was used to probe the effects of crosslinking on the resulting hydrodynamic diameters of nanoparticles in aqueous and buffered solutions. The presence of fluorine atoms in the diblock copolymers and resulting SCK nanostructures allowed for characterization by 19F NMR in addition to 1H NMR, 13C NMR, and IR spectroscopy. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4152–4166, 2001  相似文献   

6.
Reversible addition-fragmentation chain transfer polymerization at 70 °C in N,N-dimethylformamide was used to prepare poly(N-isopropylacrylamide-co-N,N-dimethylacrylamide) copolymers in various compositions to afford well-defined polymers with pre-determined molecular weight, narrow molecular weight distribution, and precise chain end structure. The copolymer compositions were determined by 1H NMR spectroscopy. The reactivity ratios of N-isopropylacrylamide (NIPAM) and N,N-dimethylacrylamide (DMA) were calculated as r NIPAM = 0.838 and r DMA = 1.105, respectively, by the extended Kelen–Tüdös method at high conversions. The lower critical solution temperature of PNIPAM can be altered by changing the DMA content in the copolymer chain. Differential scanning calorimetry and thermogravimetric analysis at different heating rates were carried out on these copolymers to understand the nature of thermal degradation and to determine its kinetics. Different kinetic models were applied to estimate various parameters like the activation energy, the order, and the frequency factor. These studies are important to understand the solid state polymer degradation of N-alkyl substituted polymers, which show great potential in the preparation of miscible polymer blends due to their ability to interact through hydrogen bonding.  相似文献   

7.
A series of novel temperature‐ and pH‐responsive graft copolymers, poly(L ‐glutamic acid)‐g‐poly(N‐isopropylacrylamide), were synthesized by coupling amino‐semitelechelic poly(N‐isopropylacrylamide) with N‐hydroxysuccinimide‐activated poly(L ‐glutamic acid). The graft copolymers and their precursors were characterized, by ESI‐FTICR Mass Spectrum, intrinsic viscosity measurements and proton nuclear magnetic resonance (1H NMR). The phase‐transition and aggregation behaviors of the graft copolymers in aqueous solutions were investigated by the turbidity measurements and dynamic laser scattering. The solution behavior of the copolymers showed dependence on both temperature and pH. The cloud point (CP) of the copolymer solution at pH 5.0–7.4 was slightly higher than that of the solution of the PNIPAM homopolymer because of the hydrophilic nature of the poly(glutamic acid) (PGA) backbone. The CP markedly decreased when the pH was lowered from 5 to 4.2, caused by the decrease in hydrophilicity of the PGA backbone. At a temperature above the lower critical solution temperature of the PNIPAM chain, the copolymers formed amphiphilic core‐shell aggregates at pH 4.5–7.4 and the particle size was reduced with decreasing pH. In contrast, larger hydrophobic aggregates were formed at pH 4.2. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4140–4150, 2008  相似文献   

8.
Well‐defined diblock and triblock copolymers composed of poly(N‐isopropylacrylamide) (PNIPAM) and poly(ethylene oxide) (PEO) were successfully synthesized through the reversible addition–fragmentation chain transfer polymerization of N‐isopropylacrylamide (NIPAM) with PEO capped with one or two dithiobenzoyl groups as a macrotransfer agent. 1H NMR, Fourier transform infrared, and gel permeation chromatography instruments were used to characterize the block copolymers obtained. The results showed that the diblock and triblock copolymers had well‐defined structures and narrow molecular weight distributions (weight‐average molecular weight/number‐average molecular weight < 1.2), and the molecular weight of the PNIPAM block in the diblock and triblock copolymers could be controlled by the initial molar ratio of NIPAM to dithiobenzoate‐terminated PEO and the NIPAM conversion. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4873–4881, 2004  相似文献   

9.
ABA-type amphiphilic triblock copolymers composed of poly(ethylene glycol)s (PEGs) with different number-average molecular weights as the hydrophilic blocks (B) and poly{6-[4-(4-ethoxyphenylazo)phenoxy]hexyl methacrylate} (PA6C) as the hydrophobic blocks (A) were prepared via atom transfer radical polymerization. These copolymers were prepared from bromo-terminated macroinitiators based on PEG6000, PEG2000, and PEG600, with CuBr/N,N,N,N,N″-pentamethyldiethylenetriamine as the catalytic system, at 85 °C in anisole. The block copolymers were characterized with 1H NMR spectroscopy and gel permeation chromatography. Differential scanning calorimetry measurements were performed to reveal the phase segregation. In contrast to those polymers with similar compositions and structures in previous reports, these amphiphilic copolymers exhibited unusual liquid-crystalline properties over a wide temperature range, being stable even at room temperature. These copolymers showed photoresponsive isomerization under the irradiation of UV–vis light both in THF solutions and in solid films. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2225–2234, 2007  相似文献   

10.
Polypeptide/inorganic hybrid copolymers were obtained by a four-step synthetic approach combining (i) atom transfer polymerization of tert-butyl acrylate, (ii) chemical modification of the bromo end groups of ATRP-polymers into primary amino group using Gabriel reaction, (iii) ring opening polymerization of Nε-trifluoroacetyl-l-lysine or γ-benzyl-l-glutamate N-carboxyanhydrides followed by (iv) the transamidification reaction using a large excess of (3-aminopropyl)trimethoxysilane to substitute the tert-butyl groups of the poly(tert-butyl acrylate) block. Products were characterized using 1H NMR, FT-IR, DSC and MALDI-TOF MS. These techniques proved that polymerization of tert-butyl acrylate was controlled whatever the molecular weight targeted and that bromide was quantitatively converted to amino end group by a original method leading to the synthesis of copolymers in the presence of N-carboxyanhydrides as monomers. Amphiphilic polypeptide/inorganic hybrid copolymers were then achieved.  相似文献   

11.
Poly(styrene‐graft‐ethyl methacrylate) graft copolymer was prepared by atom transfer radical polymerization (ATRP) with poly(styrene‐cop‐chloromethyl styrene)s in various compositions as macroinitiator in the presence of CuCl/1,2‐dipiperidinoethane at 130 °C in N,N‐dimethylformamide. Both macroinitiators and graft copolymers were characterized by elemental analysis, IR, 1H and 13C NMR, and differential scanning calorimetry. 1,2‐Dipiperidinoethane was an effective ligand of CuCl for ATRP in the graft copolymerization. The controlled growth of the side chain provided the graft copolymers with polydispersities of 1.60–2.05 in the case of poly(styrene‐cop‐chloromethyl styrene) (62:38) macroinitiator. Thermal stabilities of poly(styrene‐graft‐ethyl methacrylate) graft copolymers were investigated by thermogravimetric analysis as compared with those of the macroinitiators. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 668–673, 2003  相似文献   

12.
Poly(N‐isopropylacrylamide) (PNIPAAm) homopolymers synthesized by reversible addition–fragmentation chain transfer polymerization were used as macro‐chain‐transfer agents to synthesize smart amphiphilic block copolymers with a switchable hydrophilic–hydrophobic block of PNIPAAm and a hydrophilic block of poly(N‐dimethylacrylamide). All polymers were characterized by gel permeation chromatography, 1H NMR, and differential scanning calorimetry. The reversible micelles formed by the block copolymers of various compositions in aqueous solutions were characterized by 1H NMR, dynamic light scattering, and tensiometry. Micelles were observed in the aqueous solutions when the temperature was increased to 40 °C because of the collapse of the PNIPAAm structure, which led to a PNIPAAm hydrophobic block. The drug loading capacity was illustrated with the use of the solvatochromic Reichardt's dye and measured by ultraviolet–visible. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3643–3654, 2005  相似文献   

13.
The synthesis, characterization and self-assembly of a novel amphiphilic block copolymer containing a poly(N-vinylpyrrolidone) as a segment of hydrophilic and poly(4-vinyl benzene chloride) (PVBC) arms are reported. The copolymer was characterized by FT-IR spectroscopy 1H NMR. The composition and the molecular weights of the block copolymers were established using gel permeation chromatography and 1H NMR. The water-soluble fraction of poly(N-vinyl-2-pyrrolidone) (PVP)/PVBC block copolymers formed micelles which were investigated at 25 °C in water at 5 mg/ml concentration using a tensiometer. The morphology of micelles in aqueous solution was determined by the AFM, SANS, and SAXS methods.  相似文献   

14.
Amphiphilic block copolymers of methyl methacrylate (MMA) and sodium styrene sulfonate (SSNa) were successfully synthesized via direct atom transfer radical polymerization (ATRP) of SSNa. First, poly(sodium styrene sulfonate) (PSSNa) or poly(methyl methacrylate) (PMMA) macroinitiators were prepared using proper ATRP systems for each case. In some cases, functional initiators, which allow further reactions, were used. The macroinitiators were characterized and further used to synthesize PSSNa/PMMA block copolymers, by using proper solvent combinations, such as N,N-dimethylformamide/water or methanol/water at appropriate volume ratios, in order to ensure solubility of the synthesized amphiphilic copolymers. The molecular weight of the copolymers was determined by gel permeation chromatography, using water as eluent. By using a combination of analytical techniques like 1H NMR, FTIR and thermogravimetry, the chemical structure and the actual copolymer composition were determined. Since, the block copolymers were soluble in water, forming hydrophilic/hydrophobic domains in aqueous solution, their micellization behavior was further studied by pyrene fluorescence probing.  相似文献   

15.
The paper describes the optimization of copper(I) mediated living radical polymerization of N-hydroxysuccinimide methacrylate to achieve AB block copoly(acryl amides) offering a route to polymers with potential biomedical applications. Polymerization of N-hydroxysuccinimide methacrylate was carried out using copper(I) bromide/N-(n-propyl)-2-pyridylmethanimine catalyst with ethyl-2-bromoisobutyrate as the initiator at three different temperatures (70, 50 and 30 °C). Polymerizations at both 70 and 50 °C gave relatively high conversion, 72% and 62% respectively after 4 h. Polymerization at 30 °C the best linear first-order kinetic plot. The polydispersity remained narrow (1.15) and there was a good agreement between experimental, determined by 1H NMR, and theoretical Mn. Polymerization of N-hydroxysuccinimide methacrylate was investigated in more detail by following reactions in situ by 1H NMR. The experimental values of Mn (NMR) were quite close to the theoretical values and the polydispersities were relatively narrow (1.10-1.19). Isolated poly(N-hydroxysuccinimide methacrylate) was used as a macroinitiator for the polymerization of MMA catalyzed by Cu(I)Br in conjunction with N-(n-propyl)-2-pyridylmethanamine ligand leading to block copolymers. A poly(methyl acryl amide) is synthesized indirectly from the reaction of benzyl amine with poly(N-hydroxysuccinimide methacrylate) for 5 h with in DMSO at 50 °C under nitrogen.  相似文献   

16.
In this study, synthesis and characterization of magnetic nanocarriers are reported for drug delivery based on the amphiphilic di‐block and tri‐block copolymers of poly(ethylene glycol) (PEG) and poly(ε‐caprolactone) (PCL) with surface modified super‐paramagnetite Fe3O4 nanoparticles (magnetic nanoparticles (MNPs)). The synthesized block copolymers (methoxy poly(ethylene glycol) (mPEG)–PCL and PCL–PEG–PCL) were characterized by Fourier transform infrared (FT‐IR), 1H nuclear magnetic resonance (1H NMR), gel permeation chromatography (GPC), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC), and their properties such as critical micelle concentration, hydrophilicity to lipophilicity balance, and hydrolytic degradation were investigated. The block copolymers were functionalized with terminal azide groups (mPEG–PCL(N3) and (N3)PCL–PEG–PCL(N3)), and magnetic Fe3O4 nanoparticles were surface modified with poly(acrylic acid) (PAA) and propargyl alcohol (MNP–PAA–C≡CH). Magnetic nanocarriers were synthesized by click reaction between azide‐terminated block copolymers and MNP–PAA–C≡CH and characterized by FT‐IR, thermogravimetric analysis (TGA), dynamic light scattering (DLS), vibrating sample magnetometer (VSM), and transmission electron microscopy (TEM), and cytotoxicity was investigated by methyl thiazolyl tetrazolium assay. In vitro drug loading and release and release kinetics were investigated. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

17.
A new series of copolymers of phenol and aniline poly(PHE-co-ANI) was synthesized at platinum electrode through electro-oxidative polymerization in acetonitrile in the presence of lithium perchlorate as supporting electrolyte. Electro-polymerization was studied by cyclic voltammetry. The resultant copolymers were characterized by UV–Vis, IR, 13C and 1H NMR spectroscopy; surface morphology of the copolymers was investigated by scanning electron microscopy.  相似文献   

18.
Novel thermo‐responsive poly(N‐isopropylacrylamide)‐block‐poly(l ‐lactide)‐block‐poly(N‐isopropylacylamide) (PNIPAAm‐b‐PLLA‐b‐PNIPAAm) triblock copolymers were successfully prepared by atom transfer radical polymerization of NIPAAm with Br‐PLLA‐Br macroinitiator, using a CuCl/tris(2‐dimethylaminoethyl) amine (Me6TREN) complex as catalyst at 25 °C in a N,N‐dimethylformamide/water mixture. The molecular weight of the copolymers ranges from 18,000 to 38,000 g mol?1, and the dispersity from 1.10 to 1.28. Micelles are formed by self‐assembly of copolymers in aqueous medium at room temperature, as evidenced by 1H NMR, dynamic light scattering (DLS) and transmission electron microscopy (TEM). The critical micelle concentration determined by fluorescence spectroscopy ranges from 0.0077 to 0.016 mg mL?1. 1H NMR analysis in selective solvents confirmed the core‐shell structure of micelles. The copolymers exhibit a lower critical solution temperature (LCST) between 32.1 and 32.8 °C. The micelles are spherical in shape with a mean diameter between 31.4 and 83.3 nm, as determined by TEM and DLS. When the temperature is raised above the LCST, micelle size increases at high copolymer concentrations due to aggregation. In contrast, at low copolymer concentrations, decrease of micelle size is observed due to collapse of PNIPAAm chains. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3274–3283  相似文献   

19.
The star-shaped organic/inorganic hybrid poly(l-lactide) (PLLA) based on polyhedral oligomeric silsesquioxane (POSS) was prepared using octa(3-hydroxypropyl) polyhedral oligomeric silsesquioxane as initiator via ring-opening polymerization (ROP) of l-lactide (LLA). The molecular weight of POSS-containing star-shaped hybrid PLLA (POSSPLLA) can be well controlled by the feed ratio of LLA to initiator. The POSSPLLA was further functionalized into the macromolecular reversible addition-fragmentation transfer (RAFT) agent for the polymerization of N-isopropylacrylamide (NIPAM), leading to the POSS-containing star-shaped organic/inorganic hybrid amphiphilic block copolymers, poly(l-lactide)–block–poly(N-isopropylacrylamide) (POSS(PLLA–b–PNIPAM)). The self-assembly behavior of POSS(PLLA–b–PNIPAM) block copolymers in aqueous solution was investigated by dynamic light scattering (DLS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). DLS showed the PNIPAM block in the aggregates is temperature-responsive and its phase-transition is reversible. TEM proved that the star-shaped POSS(PLLA–b–PNIPAM) amphiphilic block copolymers can self-assemble into the vesicles in aqueous solution. The vesicular wall and coronas are composed of the hydrophobic POSS core and PLLA, and hydrophilic PNIPAM blocks, respectively. Therefore, POSSPLLA and POSS(PLLA–b–PNIPAM) block copolymers, as a class of novel organic–inorganic hybrid materials with the advantageous properties, can be potentially used in biological and medical fields.  相似文献   

20.
N‐Stearylacrylamide (SAAm), N‐oleylacrylamide (OAAm), and N‐laurylacrylamide (LAAm) were synthesized. They were characterized by 1H‐NMR, 13C‐NMR, FT‐IR, melting point measurements, and elemental analysis. The copolymerizations of SAAm, OAAm, and LAAm with 2‐[(3‐(acrylamido)propyl)dimethylammonio]ethyl 2′‐isopropyl phosphate were carried out, and a series of amphiphilic poly(acrylamide)s (1a,b, 2, and 3a,b) were obtained. These copolymers showed polyelectrolyte behavior in their viscous properties in polar solvents. X‐ray diffraction analysis indicated that the copolymers 1a,b formed similar stacked bilayers with hydrophilic groups and hydrophobic parts. The polymorphic phase transition of these copolymers was also observed by DSC. In addition, the monolayers as well as LB films of these amphiphilic copolymers were prepared on the surface of water and their π–A isotherms were investigated at different temperatures. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1293–1302, 1999  相似文献   

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