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1.
Poly(butylene terephthalate) (PBT) had been covalently attached onto the surface of multiwalled carbon nanotubes (MWNTs) by a “grafting from” method based on in situ ring‐opening polymerization (ROP) of cyclic butylene terephthalate oligomers (CBT) using MWNT‐supported initiator (MWNT‐g‐Sn). The Sn? O bond grafted on the surface of MWNTs, which was confirmed by X‐ray photoelectron spectroscopy, provided the initiating sites for ROP of CBT. Fourier transformed infrared spectroscopy and nuclear magnetic resonance were used to confirm the chemical structure of MWNT‐graft‐PBT copolymer and emission transmission electron microscope was utilized to observe the nanostructure of the PBT functionalized MWNTs. A distinct core–shell structure with PBT layer as the shell could be observed after functionalization of PBT despite it was not uniform. The results of thermogravimetric analysis indicated that the grafting ratio of PBT was about 59.3%. Furthermore, the solubility of the PBT functionalized MWNTs in phenol/tetrachloroethane had also been investigated. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

2.
The recently introduced procedure of quantitatively switching thiocarbonyl thio capped (RAFT) polymers into hydroxyl terminated species was employed to generate narrow polydispersity (PDI ≈ 1.2) sulfur‐free poly(styrene)‐block‐poly(ε‐caprolactone) polymers (26,000 ≤ Mn/g·mol?1 < 45,000). The ring‐opening polymerization (ROP) of ε‐caprolactone (ε‐CL) was conducted under organocatalysis employing 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene (TBD). The obtained block copolymers were thoroughly analyzed via size exclusion chromatography (SEC), NMR, as well as liquid adsorption chromatography under critical conditions coupled to SEC (LACCC‐SEC) to evidence the block copolymer structure and the efficiency of the synthetic process. The current contribution demonstrates that the RAFT process can serve as a methodology for the generation of sulfur‐free block copolymers via an efficient end group switch. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010  相似文献   

3.
A series of well‐defined ABC 3‐Miktoarm star‐shaped terpolymers [Poly(styrene)‐Poly(ethylene oxide)‐Poly(ε‐caprolactone)](PS‐PEO‐PCL) with different molecular weight was synthesized by combination of the “living” anionic polymerization with the ring‐opening polymerization (ROP) using macro‐initiator strategy. Firstly, the “living” poly(styryl)lithium (PS?Li+) species were capped by 1‐ethoxyethyl glycidyl ether(EEGE) quantitatively and the PS‐EEGE with an active and an ethoxyethyl‐protected hydroxyl group at the same end was obtained. Then, using PS‐EEGE and diphenylmethylpotassium (DPMK) as coinitiator, the diblock copolymers of (PS‐b‐PEO)p with the ethoxyethyl‐protected hydroxyl group at the junction point were achieved by the ROP of EO and the subsequent termination with bromoethane. The diblock copolymers of (PS‐b‐PEO)d with the active hydroxyl group at the junction point were recovered via the cleavage of ethoxyethyl group on (PS‐b‐PEO)p by acidolysis and saponification successively. Finally, the copolymers (PS‐b‐PEO)d served as the macro‐initiator for ROP of ε‐CL in the presence of tin(II)‐bis(2‐ethylhexanoate)(Sn(Oct)2) and the star(PS‐PEO‐PCL) terpolymers were obtained. The target terpolymers and the intermediates were well characterized by 1H‐NMR, MALDI‐TOF MS, FTIR, and SEC. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1136–1150, 2008  相似文献   

4.
Poly(styrene) macromercaptanes (Mn = 1900, 3600, and 6100 g mol?1, PDI ≈ 1.2) derived from thiocarbonyl thio capped polymers prepared via reversible addition fragmentation chain transfer polymerization were employed to initiate the ring opening polymerization (ROP) of D ,L ‐lactide under conditions of organo‐catalyis employing 4,4‐dimethylaminopyridine. Poly(styrene)‐block‐poly(lactide) polymers of number average molecular weights up to 25,000 g mol?1 (PDI ≈ 1.2 to 1.6) were obtained and characterized via multiple detection size exclusion chromatography (SEC) using refractive index as well as UV detection. In addition, diffusion ordered nuclear magnetic resonance and liquid chromatography at critical conditions (of both polystyrene as well as poly(lactide) were employed to assess the copolymers' structure. Furthermore, it was demonstrated that polyethylenes capped with a thiol moiety can also be readily chain extended in a ROP employing D ,L ‐lactide, evidenced via NMR and high temperature SEC. This study indicates that the direct use of macromercaptantes is indeed a methodology to switch from a radical to a ROP process. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011  相似文献   

5.
2‐cyanoprop‐2‐yl dithiobenzoate (CPDB) mediated RAFT polymerization of dimethylaminoethyl methacrylate (DMAEMA) was carried out in dioxane at 90 °C. The influence of several parameters, such as the monomer to CPDB molar ratio (100 to 500), the monomer concentration (2 mol·L?1 to 5.9 mol·L?1), and CPDB to initiator molar ratio (1 to 10), was evaluated with regards to conversion and polymerization duration, as well as control of molar mass and molar mass distributions. Number average molar masses from 10,000 to 70,000 g·mol?1 can be targeted. The determination of the molar masses has been carried out by size exclusion chromatography (SEC) with a refractometer detector with poly(methyl methacrylate) (PMMA) standards. The experimental values were lower than the expected ones. Then, SEC in aqueous medium with an online laser light scattering detector was used both to get absolute molar masses and to recalibrate the SEC column in THF. Characterization of well‐controlled PDMAEMA samples has been performed by proton NMR spectroscopy and matrix assisted laser desorption ionization time of flight mass spectrometry. Finally, a chain extension experiment was evaluated with regard to living features. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3551–3565, 2005  相似文献   

6.
New super‐tough poly(butylene terephthalate) (PBT)/poly(ethylene‐octene) copolymer (PEO) blends containing 2 wt% poly(ethylene‐co‐glycidyl methacrylate) (EGMA) as a compatibilizer were obtained by extrusion and injection molding. The blends comprised of an amorphous PBT‐rich phase with some miscibilized EGMA, a pure PEO amorphous phase, and a crystalline PBT phase that was not influenced by the presence of either PEO or EGMA. The blends showed a fine particle size up to 20 wt% PEO content. Super‐tough blends were obtained with PEO contents equal to or higher than 10%. The maximum toughness was very high (above 710 J/m) and was attained with 20% PEO without chemical modification of the commercial components used. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

7.
Segmented copolyesters, namely, poly(butylene terephthalate)–poly(ethylene terephthalate‐co‐isophthalate‐co‐sebacate) (PBT‐PETIS), were synthesized with the melting transesterification processing in vacuo condition involving bulk polyester produced on a large scale (PBT) and ternary amorphous random copolyester (PETIS). Investigations on the morphology of segmented copolyesters were undertaken. The two‐phase morphology model was confirmed by transmission electron microscopy and dynamic mechanical thermal analysis. One of the phases was composed of crystallizable PBT, and the other was a homogeneous mixture of PETIS and noncrystallizable PBT. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2257–2263, 2003  相似文献   

8.
The simultaneous ring‐opening polymerization (ROP) of ε‐caprolactone (ε‐CL) and 2‐hydroxyethyl methacrylate (HEMA) polymerization via reversible addition fragmentation chain transfer (RAFT) chemistry and the possible access to graft copolymers with degradable and nondegradable segments is investigated. HEMA and ε‐CL are reacted in the presence of cyanoisopropyl dithiobenzoate (CPDB) and tin(II) 2‐ethylhexanoate (Sn(Oct)2) under typical ROP conditions (T > 100 °C) using toluene as the solvent in order to lead to the graft copolymer PHEMA‐g‐PCL. Graft copolymer formation is evidenced by a combination of size‐exclusion chromatography (SEC) and NMR analyses as well as confirmed by the hydrolysis of the PCL segments of the copolymer. With targeted copolymers containing at least 10% weight of PHEMA and relatively small PHEMA backbones (ca. 5,000–10,000 g mol?1) the copolymer grafting density is higher than 90%. The ratio of free HEMA‐PCL homopolymer produced during the “one‐step” process was found to depend on the HEMA concentration, as well as the half‐life time of the radical initiator used. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3058–3067, 2008  相似文献   

9.
Ring‐opening polymerization (ROP) of ε‐caprolactone (CL) using salicylic acid (SAA) as the organocatalyst and benzyl alcohol as the initiator in bulk at 80 °C successfully proceeded to give a narrowly distributed poly(ε‐caprolactone) (PCL). In addition, 2‐hydroxyethyl methacrylate, propargyl alcohol, 6‐azido‐1‐hexanol, and methoxy poly(ethylene glycol) were also used as functional initiators. The 1H NMR, SEC, and MALDI‐TOF MS measurements of the PCL clearly indicate the presence of the initiator residue at the chain end, implying that the SAA‐catalyzed ROP of CL was through the activated monomer mechanism. The kinetic experiments confirmed the controlled/living nature of the SAA‐catalyzed ROP of CL. Furthermore, the block copolymerization of CL and δ‐valerolactone successfully proceeded to give poly(ε‐caprolactone)‐block‐poly(δ‐valerolactone). © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1185–1192  相似文献   

10.
The polymerization of a cyclic butylene terephthalate (CBT) oligomer was studied as a function of temperature (T=200 and 260°C, respectively) by modulated DSC (MDSC). The first heating was followed by cooling after various holding times (5, 15 and 30 min) prior to the second heating which ended always at T=260°C. This allowed us to study the crystallization and melting behavior of the resulting polybutylene terephthalate (PBT), as well. In contrary to the usual belief, the CBT polymerization is exothermic and the related process is superimposed to that of the CBT melting. The melting behavior of the PBT was affected by the polymerization mode (performed below or above the melting temperature of the PBT product) of the CBT. Annealing above the melting temperature of PBT yielded a product featuring double melting. This was attributed to the presence of crystallites with different degrees of perfection. The crystals perfection which occurred via recrystallization/remelting was manifested by a pronounced exothermic peak in the non-reversing trace.  相似文献   

11.
One‐step synthesis of block‐graft copolymers by reversible addition‐fragmentation chain transfer (RAFT) and ring‐opening polymerization (ROP) by using a novel initiator was reported. Block‐graft copolymers were synthesized in one‐step by simultaneous RAFT polymerization of n‐butylmethacrylate (nBMA) and ROP of ε‐caprolacton (CL) in the presence of a novel macroinitiator (RAFT‐ROP agent). For this purpose, first epichlorohydrin (EPCH) was polymerized by using H2SO4 via cationic ring‐opening mechanism. And then a novel RAFT‐ROP agent was synthesized by the reaction of potassium ethyl xanthogenate and polyepichlorohydrin (poly‐EPCH). By using the RAFT‐ROP agent, poly[CL‐b‐EPCH‐b‐CL‐(g‐nBMA)] block‐graft copolymers were synthesized. The principal parameters such as monomer concentration, initiator concentration, and polymerization time that affect the one‐step polymerization reaction were evaluated. The block lengths of the block‐graft copolymers were calculated by using 1H‐nuclear magnetic resonance (1H NMR) spectrum. The block length could be adjusted by varying the monomer and initiator concentrations. The characterization of the products was achieved using 1H NMR, Fourier‐transform infrared spectroscopy, gel‐permeation chromatography, thermogravimetric analysis, differential scanning calorimetry, elemental analysis, and fractional precipitation (γ) techniques. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2651–2659  相似文献   

12.
A novel high energetic material, 1‐amino‐1‐methylamino‐2,2‐dinitroethylene (AMFOX‐7), was synthesized through 1,1‐diamino‐2,2‐dinitroethylene (FOX‐7) reacting with methylamine in N‐methyl pyrrolidone (NMP) at 80.0°C, and its structure was determined by single crystal X‐ray diffraction. The crystal is monoclinic, space group P21/m with crystal parameters of a=6.361(3) Å, b=7.462(4) Å, c=6.788(3) Å, β=107.367(9)°, V=307.5(3) Å3, Z=2, µ=0.160 mm?1, F(000)=168, Dc=1.751 g·cm?3, R1=0.0463 and wR2=0.1102. Thermal decomposition of AMFOX‐7 was studied, and the enthalpy, apparent activation energy and pre‐exponential constant of the exothermic decomposition reaction are 303.0 kJ·mol?1, 230.7 kJ·mol?1 and 1021.03 s?1, respectively. The critical temperature of thermal explosion is 245.3°C. AMFOX‐7 has higher thermal stability than FOX‐7.  相似文献   

13.
Poly(vinyl laurate) (PVL) and poly(vinyl stearate) (PVS) were synthesized by means of cobalt‐mediated radical polymerization (CMRP). Cobalt(II) diacetylacetonate (Co(acac)2) was demonstrated to control the radical polymerization of these monomers in solution. Molecular weights up to 15,000 g·mol?1 were obtained with reasonably low polydispersity indices (PDI < 1.3). The efficiency of the redox initiator [lauroyle peroxide (LPO)/citric acid (CA)] was found to be low (around 10%) as already reported for vinyl acetate. The solvent and temperature were found to have a very weak influence on the initiator efficiency. It appeared that CA played no role in the initiation process that only involved a redox reaction between LPO and Co(acac)2. PVL‐b‐PVS diblock copolymers could be synthesized using two strategies: (1) Sequential addition, that is, addition of the second monomer (VS) at high conversion of the first one (VL). (2) Macroinitiator technique, that is, isolation of a PVL macroinitiator then polymerization of VS from this cobalt functionalized macroinitiator. Both techniques allowed the synthesis of diblock copolymers with molar masses around 25,000 g·mol?1 and PDI lower than 1.4. The resulting materials were characterized by DSC, revealing that both blocks exhibit side‐chain crystallinity and phase segregate in the bulk. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012  相似文献   

14.
The titanium complexes with one ( 1a , 1b , 1c ) and two ( 2a , 2b ) dialkanolamine ligands were used as initiators in the ring‐opening polymerization (ROP) of ε‐caprolactone. Titanocanes 1a and 1b initiated living ROP of ε‐caprolactone affording polymers whose number‐average molecular weights (Mn) increased in direct proportion to monomer conversion (Mn ≤ 30,000 g mol?1) in agreement with calculated values, and were inversely proportional to initiator concentration, while the molecular weight distribution stayed narrow throughout the polymerization (Mw/Mn ≤ 1.2 up to 80% monomer conversion). 1H‐NMR and MALDI‐TOF‐MS studies of the obtained poly(ε‐caprolactone)s revealed the presence of an isopropoxy group originated from the initiator at the polymer termini, indicating that the polymerization takes place exclusively at the Ti–OiPr bond of the catalyst. The higher molecular weight polymers (Mn ≤ 70,000 g mol?1) with reasonable MWD (Mw/Mn ≤ 1.6) were synthesized by living ROP of ε‐caprolactone using spirobititanocanes ( 2a , 2b ) and titanocane 1c as initiators. The latter catalysts, according MALDI‐TOF‐MS data, afford poly(ε‐caprolactone)s with almost equal content of α,ω‐dihydroxyl‐ and α‐hydroxyl‐ω(carboxylic acid)‐terminated chains arising due to monomer insertion into “Ti–O” bond of dialkanolamine ligand and from initiation via traces of water, respectively. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1230–1240, 2010  相似文献   

15.
The thermal behavior and kinetic parameters of the exothermic decomposition reaction of N‐N‐bis[N‐(2,2,2‐tri‐nitroethyl)‐N‐nitro]ethylenediamine in a temperature‐programmed mode have been investigated by means of differential scanning calorimetry (DSC). The results show that kinetic model function in differential form, apparent activation energy Ea and pre‐exponential factor A of this reaction are 3(1 ‐α)2/3, 203.67 kJ·mol?1 and 1020.61s?1, respectively. The critical temperature of thermal explosion of the compound is 182.2 °C. The values of ΔS ΔH and ΔG of this reaction are 143.3 J·mol?1·K?1, 199.5 kJ·mol?1 and 135.5 kJ·mol?1, respectively.  相似文献   

16.
The eight‐shaped poly(ethylene oxide) (PEO) is synthesized by a combination of Glaser coupling with ring‐opening polymerization (ROP). Firstly, the star‐shaped (PEO‐OH) 4 is synthesized by ROP of ethylene oxide (EO) using pentaerythritol as an initiator and diphenylmethyl potassium (DPMK) as a deprotonated agent, and then the alkyne group is introduced onto the PEO arm‐end to give (PEO‐Alkyne) 4 in a NaH/tetrahydrofuran (THF) system. The intramolecular cyclization is carried out by a Glaser coupling reaction in a pyridine/CuBr/N,N,N′,N″,N″‐pentamethyldiethylenetriamine (PMDETA) system at room temperature in an air atmosphere, and eight‐shaped PEO was formed with high efficiency (almost 100%). The target polymers and intermediates were well characterized by SEC, MALDI‐TOF MS, 1H NMR and FT‐IR in detail.

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17.
The copolymer of polystyrene‐block‐poly(ethylene oxide)‐block‐poly (tert‐butyl acrylate) (PS‐b‐PEO‐b‐PtBA) was prepared, the synthesis process involved ring‐opening polymerization (ROP), nitroxide‐mediated polymerization (NMP), and atom transfer radical polymerization (ATRP), and 4‐hydroxyl‐2,2,6,6‐tetramethylpiperidinyl‐1‐oxy (HTEMPO) was used as parent compound. The PEO precursors with α‐hydroxyl‐ω‐2,2,6,6‐tetramethylpiperidinyl‐1‐oxy end groups(TEMPO‐PEO‐OH) were first obtained by ROP of EO using HTEMPO and diphenylmethylpotassium (DPMK) as the coinitiator. The TEMPO at one end of PEO chain mediated the polymerization of St using benzoyl peroxide as initiator. The resultant PS‐b‐PEO‐OH reacted further with 2‐bromoisobutyryl bromide and then initiated the polymerization of tBA in the presence of CuBr and PMDETA by ATRP. The ternary block copolymers PS‐b‐PEO‐b‐PtBA and intermediates were characterized by gel permeation chromatography, Fourier transform infrared, and nuclear magnetic resonance spectroscopy in detail. Differential scanning calorimetry measurements confirmed that the PS‐b‐PEO‐b‐PtBA with PEO as middle block can weaken the interaction between PS and PtBA blocks, the glass transition temperature (Tg) for two blocks were approximate to their corresponding homopolymers comparing with the PEO‐b‐PS‐b‐PtBA with PEO as the first block. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2624–2631, 2008  相似文献   

18.
Simple, rapid and reliable method for the determination of albendazole (ABZ) was described. This includes the utility of some Π‐acceptors such as 2,3‐dichloro‐5,6‐dicyano‐p‐benzoquinone (DDQ) and 3,6‐dichloro‐2,5‐dihy‐ droxy‐p‐benzoquinone (p‐CLA) for estimation of ABZ drug (act as donor). The experimental conditions were optimized and the system obeys Beer's law for 7.50–80 and 10.00–85.00 µg·mL?1 of ABZ using DDQ and p‐CLA, respectively. The molar absorptivity and Sandell sensitivity were calculated to be 1.83×103 and 1.12×103 L·mol?1·cm?1, and 2.60 and 3.40 ng·cm?2 using DDQ and p‐CLA, respectively. The limits of detection and quantification were calculated to be (7.42 and 6.73) and (9.94 and 4.13) µg·mL?1 using DDQ and p‐CLA, respectively. The proposed methods were successfully applied to the determination of ABZ in commercially available dosage forms. The reliability of the assays was established by parallel determination by the official method and recovery studies. The chemical structures of the solid charge‐transfer (CT) complexes formed via reaction between ABZ under study and Π‐acceptors, have been elucidated using elemental analyses (C, H and N), IR, 1H NMR and mass spectra.  相似文献   

19.
In the present study, n‐butyl acrylate macromonomer (BAMM) (Mn = 1900 g mol?1; PDI = 1.96) has been synthesized via a high‐temperature polymerization process. Subsequently, the olefinic termini of the BAMM have been transformed into a diol via a dihydroxylation process using KMnO4 as an oxidizing agent. The OH‐terminated macroinitiator pBA(OH)2 has subsequently been employed for the ring‐opening polymerization (ROP) of ε‐caprolactone via various catalytic systems, that is, organo‐(1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene), metal (tin(II) 2‐ethylhexanoate), and enzymatic catalysis (Novozym® 435). The obtained pBA‐b‐pCL block copolymers and the initiation efficiency of the BAMM macroinitiator have been investigated via size exclusion chromatography (SEC), electrospray ionization–mass spectrometry (ESI‐MS) hyphenated with SEC and liquid chromatography at the critical conditions of both poly(ε‐caprolactone) (pCL) and pBA. The in vitro enzyme catalysis (eROP) approach proved to be the most efficient catalysis system due to minor transesterification side reactions during the polymerization process. However, side reactions such as transesterifications occur in each catalytic system and—while they cannot be suppressed—they can be minimized. The species generated during the eROP process include the desired block copolymer pBA‐b‐pCL as main species as well as pCL homopolymer and residual macroinitiator pBA(OH)2. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012  相似文献   

20.
Well‐defined ABCD 4‐Miktoarm star‐shaped quarterpolymers of [poly(styrene)‐poly(tert‐butyl acrylate)‐poly(ethylene oxide)‐poly(isoprene)] [star(PS‐PtBA‐PEO‐PI)] were successfully synthesized by the combination of the “click” chemistry and multiple polymerization mechanism. First, the poly(styryl)lithium (PS?Li+) and the poly(isoprene)lithium (PI?Li+) were capped by ethoxyethyl glycidyl ether (EEGE) to form the PS and PI with both an active ω‐hydroxyl group and an ω′‐ethoxyethyl‐protected hydroxyl group, respectively. After these two hydroxyl groups were selectively modified to propargyl and 2‐bromoisobutyryl group for PS, the resulted PS was used as macroinitiator for ATRP of tBA monomer and the diblock copolymer PS‐b‐PtBA with a propargyl group at the junction point was achieved. Then, using the functionalized PI as macroinitiator for ROP of EO monomer and bromoethane as blocking agent, the diblock copolymer PI‐b‐PEO with a protected hydroxyl group at the conjunction point was synthesized. After the hydrolysis, the recovered hydroxyl group of PI‐b‐PEO was modified to bromoacetyl and then azide group successively. Finally, the “click” chemistry between them was proceeded smoothly. The obtained star‐shaped quarterpolymers and intermediates were characterized by 1H NMR, FT‐IR, and SEC in detail. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2154–2166, 2008  相似文献   

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