Cationic ring-opening copolymerization of 1, 4-anhydro-2, 3-O-isopropylidene-α-D-ribo-pyranose (AIRP) with 1,4-anhydro-2,3-di-O-benzyl-α-D-ribopyranose (ADBR) preparedfrom D-ribose was studied. Copolymerization usin...Cationic ring-opening copolymerization of 1, 4-anhydro-2, 3-O-isopropylidene-α-D-ribo-pyranose (AIRP) with 1,4-anhydro-2,3-di-O-benzyl-α-D-ribopyranose (ADBR) preparedfrom D-ribose was studied. Copolymerization using SbCl_5 or BF_3 OEt_2 as catalyst atlow temperature gave stereoregular (1→4)β-D-ribofuranan (C-1 and C-4 ring cleavagesee Scheme 1) or (1→5) α-D-ribofuranan (C-1 and C-5 ring cleavage) respectively. Theeffects of catalysts, reaction time and temperatures on yield and stereoregularity of the ob-tained polymers were studied. Polymers were characterized by molecular weight, ~1HNMR,^(13)CNMR and optical rotation.展开更多
Cationic ring-opening polymerization of 3,3-bis(chloromethyl)oxacyclobutane catalyzed by BF3.OEt2 was carded out in ionic liquids [bmim]BF4 and [bmim]PF6. The influences of BCMO concentration and molar ratio of BCMO...Cationic ring-opening polymerization of 3,3-bis(chloromethyl)oxacyclobutane catalyzed by BF3.OEt2 was carded out in ionic liquids [bmim]BF4 and [bmim]PF6. The influences of BCMO concentration and molar ratio of BCMO/BF3.OEt2 on the molecular weights and yield of PBCMO were investigated. The polymerization in ionic liquids proceed to high conversions, although molecular weights are limited, similar to polymerization in organic solvent such as CH2Cl2. Follow a viewpoint of green chemistry, we feel ionic liquid [bmim]BF4 is superior to [bmim]PF6. Extracting [bmim]PF6 from the product using organic solvent as extractant limits its advantage as a green reaction media.展开更多
The random copolymer poly (1, 3-pentadiene-co-styrene) formed through cationic copolymerization using the ~ethylamine hydrochloride and hydrous aluminium chloride (Et3NHCl-AlCl3) room temperature ionic liquid as i...The random copolymer poly (1, 3-pentadiene-co-styrene) formed through cationic copolymerization using the ~ethylamine hydrochloride and hydrous aluminium chloride (Et3NHCl-AlCl3) room temperature ionic liquid as initiating agent in toluene was analyzed using IR spectra in conjunction with gel permeation chromatography (GPC). The room temperature ionic liquid was found to have high initiatic activity for copolymerization.展开更多
The ring-opening copolymerization of adipic anhydride with propylene oxide was carried out with yttrium triflates as a catalyst. Poly(propylene adipate) could be synthesized by controlling the copolymerization condi...The ring-opening copolymerization of adipic anhydride with propylene oxide was carried out with yttrium triflates as a catalyst. Poly(propylene adipate) could be synthesized by controlling the copolymerization conditions. The copolymerization procedure was tracked by ^1H NMR analyses.展开更多
New highly stereoregular 2, 3 -di- O-(p-azidobenzyl )-(1 →5 ) - α-D -ribofuranan was synthesized byselective ring-opening polymerization of 1, 4-anhydro-2, 3 - di-O -(p-azidobenzyl )-α-D -ribopyranose(ADABR) using ...New highly stereoregular 2, 3 -di- O-(p-azidobenzyl )-(1 →5 ) - α-D -ribofuranan was synthesized byselective ring-opening polymerization of 1, 4-anhydro-2, 3 - di-O -(p-azidobenzyl )-α-D -ribopyranose(ADABR) using phosphorus pentafluoride or tin tetrachloride as catalyst at low temperature indichloromethane. The monomer was obtained by the reaction of p - bromomethyl -phenyleneazide with 1, 4 -anhydro-α-D-ribose in DMF. The structure of poly(ADANR) was identified by specific rotation and ^(13)C-NMR spectroscopy. Acid chloride-AgCl_4 complex catalyst such as CH_2=C(CH_3)C^+OClO_4^- used in thepolymerization resulted in polymers with mixed structures, i.e. (1→5)-α-D-ribofuranosidic and (1→4)-β-D-ribopyranosidic units. However, with C_6H_5C^+OClO_4^- as catalyst, pure (1→5)-α-D-ribofuranan was obtained.The effects of catalyst, polymerization temperature and time on polymer stereoregularity were examined, andthe mechanism of the ring-opening polymerization was discussed.展开更多
Recyclable polymers offer a great opportunity to address the environmental issues of plastics.Herein,functionalization of recyclable polymers,poly((R)-3,4-trans six-membered ring-fused GBL)(P((R)-M)),were reported via...Recyclable polymers offer a great opportunity to address the environmental issues of plastics.Herein,functionalization of recyclable polymers,poly((R)-3,4-trans six-membered ring-fused GBL)(P((R)-M)),were reported via end-group modifications and block/random copolymerizations.Di-n-butylmagnesium was selected to catalyze ring-opening polymerization(ROP)of(R)-M in the presence of a series of functional alcohols as the initiators.Block/random copolymerizations of(R)-M andε-caprolactone(ε-CL),L-lactide(L-LA)and trimethylene carbonate(TMC)were performed to control the onset decomposition temperature(T_(d)),melting temperature(T_(m))and glass transition temperature(T_(g)).These functionalized recyclable polymers would find broad applications as the sustainable plastics.展开更多
A new quaternary ammonium salt monomer was synthesized and a quaternary amination of lignin( noted as QL), with the monomer was carried out by grafting copolymerization. The products were characterized by Fourier Tr...A new quaternary ammonium salt monomer was synthesized and a quaternary amination of lignin( noted as QL), with the monomer was carried out by grafting copolymerization. The products were characterized by Fourier Transform Infrared spectroscopy( FTIR). The experimental results indicate that the yield of the monomer was 99.06%, and the conversion of the monomer and the grafting yield of QL were 93.69% and 185.78%, respectively. The feasibility of QL as the flocculant to be applied in color removal of five artificial dyes, erioehrome black T(dye A), gongo red(dye B ), direct fast black G (dye C ), cuprofix blue green B (dye D ), and acid black ATT (dye E ) was examined. Results show that OL exhihits the favorable flocculation nerformance and high stability.展开更多
A series of cyclic (arylene phosphonate) oligomers were prepared by reaction of phenylphosphonic dichloride (PPD) with various bisphenols under pseudo-high dilution conditions via interfacial polycondensation. The yie...A series of cyclic (arylene phosphonate) oligomers were prepared by reaction of phenylphosphonic dichloride (PPD) with various bisphenols under pseudo-high dilution conditions via interfacial polycondensation. The yield of cyclic (arylene phosphonate) oligomers is over 85% by using hexadecyltrimethylammoniun bromide as phase transfer catalyst (PTC) at 0 'C . The structures of the cyclic oligomers were confirmed by a combination of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and IR analysis. These cyclic oligomers undergo facile ring-opening polymerization in the melt by using potassium 4,4'-biphenoxide as the initiator to give linear polyphosphonate. Free-radical ring-opening polymerization of cyclic(arylene phosphonate) oligomers containing sulfur linkages was also performed in the melt using 2,2'-dithiobis(benzothiazole) (DTB) as the initiator at 270 °C and the resulting polymer had a Mw, of 8 × 103 with a molecular weight distribution of 4. Ring-opening copolymerization of these cyclic oligomers with cyclic carbonate oligomers was also achieved. The average molecular weight of the resulting copolymer is higher than the corresponding homopolymer and the thermal stability of the copolymer is better than the corresponding homopolymer.展开更多
Two oxetane-derived monomers, 3-(2-cyano-ethoxy)methyl- and 3-(methoxy-(triethylenoxy))methyl-3'- methyloxetane (COX and MTOX), were prepared from 3-hydroxymethyl-3'-methyloxetane. Their homo- and copolymeri...Two oxetane-derived monomers, 3-(2-cyano-ethoxy)methyl- and 3-(methoxy-(triethylenoxy))methyl-3'- methyloxetane (COX and MTOX), were prepared from 3-hydroxymethyl-3'-methyloxetane. Their homo- and copolymerization in solution were carried out by the cationic ring-opening polymerization with BF3 · Et2O and 1,4-butanediol as co-initiator. The molecular weight and molecular weight distribution were determined using GPC so as to reveal the competition and interchange between active chain end (ACE) and activated monomer (AM) mechanism in the process. The reactivity ratios of the two monomers were calculated according to Kelen-Tudos using ^1H-NMR analysis. The influence of functional side chains in the monomers on the copolymerization behaviors was discussed in virtue of the reactivity ratio data. When doped with lithium salt LiTFSI, the ion conductivity of the homopolymer of MTOX reached 10^-3.58 S/cm at 30℃ and 10^-2.73 S/cm at 80℃, respectively, showing its potential to be used as polymer electrolyte for lithium ion battery.展开更多
Efficient synthesis of polyester polyols with tunable molecular weight and microstructures from cyclic anhydride/epoxide mixtures by taking advantage of chain transfer reaction remains a great challenge,because most o...Efficient synthesis of polyester polyols with tunable molecular weight and microstructures from cyclic anhydride/epoxide mixtures by taking advantage of chain transfer reaction remains a great challenge,because most of the catalysts exhibit poor tolerance to chain transfer agent(CTA).In this contribution,we demonstrated that potassium acetate(KOAc)and 18-crown-6(18-C-6)combination has great potential in the synthesis of diverse polyester polyols with controllable molecular weight and high-end group fidelity.Com-pared with KOAc,KOAc/18-C-6 pair could induce a much faster chain transfer between the active and dormant chains,and thus produce polyester polyols with narrow and monomodal distribution.In addition,polyester polyols could be efficiently prepared in laboratory by using commercially available cyclic anhydride without further purification(containing about 2%diacid residual as CTA)with an extremely low catalyst loading([catalyst pair]:[anhydride]:[epoxide]=1:50000:250000,[catalyst pair]=0.0004 mol%).KOAc/18-C-6 could also promote the self-switchable copolymerization of cyclic anhydride/epoxide/cyclic ester mixtures.Ring-opening copolymerization of cyclic ester was initiated automatically after the full conversion of cyclic anhydride,finally producing polyester polyols with ABA-type block structure.展开更多
Amphiphilic copolymer of 5-benzyloxytrimethylene carbonate (BTMC) with poly (vinyl pyrrolidone) (PVP) was successfully synthesized using immobilized porcine pancreas lipase (IPPL) or SnOct2 as catalyst. Hydrox...Amphiphilic copolymer of 5-benzyloxytrimethylene carbonate (BTMC) with poly (vinyl pyrrolidone) (PVP) was successfully synthesized using immobilized porcine pancreas lipase (IPPL) or SnOct2 as catalyst. Hydroxyl terminated PVP, synthesized with 2-mercaptoethanol as a chain transfer reagent, was employed as a rnacroinitiator. The resulting copolymers were characterized by GPC, ^1H NMR and IR. Increasing the BTMC/PVP-OH feed ratio ([B]/[P]) resulted in the increase of Mn of corresponding copolymers and the decrease of Mw/Mn. Immobilized enzyme has comparable catalytic activity to SnOct2 for the copolymerization.展开更多
The copolymerization of 4-vinylbenzyl chloride (VBC) and vinyl acetate (VAC) was carried out in toluene at 75℃ via radical polymerization using 2,2'-azo-bis-(isobutyronitrile) (AIBN) as an initiator. The ran...The copolymerization of 4-vinylbenzyl chloride (VBC) and vinyl acetate (VAC) was carried out in toluene at 75℃ via radical polymerization using 2,2'-azo-bis-(isobutyronitrile) (AIBN) as an initiator. The random copolymers of poly(4-vinylbenzyl chloride-co-vinyl acetate) (P(VBC-co-VAC)) with number average molecular weight (Mn) from 2000 to 6900, relatively narrow molecular weight distribution (MWD, Mw/Mn ca. 2.0) and with different copolymer composition of 4-vinylbenzyl chloride (VBC) from 17 mol% to 62 mol% could be obtained. The P(VBC-co-VAC) copolymers with an average number of 7 to 13 initiating sites of benzyl chloride per macromolecule could be used for the cationic polymerization of isobutylene (IB). The cationic polymerizations of IB were further conducted by using P(VBC-co-VAC) copolymers as macroinitiators in conjunction with TICl4 at -40℃ in CH2Cl2. The effects of VBC/TiCl4 (molar ratio) on monomer conversion, Mn and MWD of the resultant copolymers were investigated under 3 sets of conditions. It is found that P(VBC-co-VAC)-g-PIB copolymers with relatively narrow MWD (Mw/Mn ca. 2.0) and with terminal tert-chlorine functional groups in branched PIB chains could be successfully synthesized when VBC/TiCl4 (molar ratio) was set in the range from 0.10 to 1.12. The unimodal GPC curve of the P(VBC-co-VAC)-g-PIB copolymers by RI detector was almost in harmony with the GPC curve by UV detector. The TEM image of the P(VBC-co-VAC)-g-PIB copolymer stained by RuO indicated that the copolymer formed a two-phase morphology with P(VBC-co-VAC)-rich domains of 20-100 um in size tethered by PIB branch segments.展开更多
A kind of novel triblock copolymers of poly(γ-benzyl L-glutamate)-b-poly(tetrahydrofuran)-b-poly(γ-benzyl L-glutamate)s(PBLG-b-PTHF-b-PBLG)was synthesized by using bis(3-aminopropyl)terminated polytetrahydrofuran to...A kind of novel triblock copolymers of poly(γ-benzyl L-glutamate)-b-poly(tetrahydrofuran)-b-poly(γ-benzyl L-glutamate)s(PBLG-b-PTHF-b-PBLG)was synthesized by using bis(3-aminopropyl)terminated polytetrahydrofuran to initiate the ring-opening polymerization ofγ-benzyl L-glutamate N-carboxyanhydride(BLG-NCA).The corresponding multiblock poly(amino acid-urea)s were prepared in one-pot protocol from the chain extension of PBLG-b-PTHF-b-PBLG with MDI.The resulting triblock and multiblock copolymers were characterized by FTIR,~1H-NMR,^(13)C-NMR and GPC techniques.It is demonstrated that the chain extension has taken place to give rise to the copolymers with the well-defined block composition and narrow molecular weight distribution.A distinct T_g arising from the hard-segments was observed in all the copolymers.Their mechanical properties showed an increasing trend with the molecular weight enhancement of the prepolymers.展开更多
Styrene-isoprene-styrene(SIS) block copolymer was modified into epoxidized styrene-isoprene-styrene(ESIS) block copolymer with performic acid generated in situ from hydrogen peroxide and formic acid.The structure ...Styrene-isoprene-styrene(SIS) block copolymer was modified into epoxidized styrene-isoprene-styrene(ESIS) block copolymer with performic acid generated in situ from hydrogen peroxide and formic acid.The structure and property of ESIS were characterized by Fourier transform infrared(FT-IR) spectroscopy,gel permeation chromatography(GPC),thermogravimetric/differential thermogravimetric(TG/DTG),melt flow rate(MFR) and dynamic mechanical analysis(DMA),and the reaction mechanism in the process of epoxidation was analyzed.The results showed that C=C double bonds of 1,4-structure were more active than that of 3,4-structure in polyisoprene chains.With epoxidation reaction proceeding,the whole tendency of molecular weight increased and molecular weight distribution widened,and MFR firstly increased and latterly decreased.The heat resistance of ESIS was superior to that of SIS.When SIS was changed into ESIS with 15.3% of mass fraction of epoxide groups,Tg of polyisoprene chains increased from-45.3 ℃ to 10.9 ℃.In the earlier period of epoxidation,some molecular chains ruptured and new substances with low molecular weight formed.However,in the latter period,crosslinking reaction between molecular chains which was initiated by epoxide groups or C=C double bonds occurred and crosslinked insoluble substances came into being.展开更多
Phosphazene base,t-BuP2,was employed to catalyze the proton transfer polymerization(PTP)of 2-hydroxyethyl acrylate(HEA),and PTP was further combined with ring-opening polymerization(ROP)to exploit a new type of hybrid...Phosphazene base,t-BuP2,was employed to catalyze the proton transfer polymerization(PTP)of 2-hydroxyethyl acrylate(HEA),and PTP was further combined with ring-opening polymerization(ROP)to exploit a new type of hybrid copolymerization.The studies on homopolymerization showed that t-BuP2 was a particularly efficient catalyst for the polymerization of HEA at room temperature,giving an excellent monomer conversion.Throughout the polymerization,transesterification reactions were unavoidable,which increased the randomness in the structures of the resulting polymers.The studies on copolymerization showed that t-BuP2 could simultaneously catalyze the hybrid copolymerization via the combination of PTP and ROP at 25°C.During copolymerization,HEA not only provided hydroxyl groups to initiate the ROP ofε-caprolactone(CL)but also participated in the polymerization as a monomer for PTP.The copolymer composition was approximately equal to the feed ratio,demonstrating the possibility to adjust the polymeric structure by simply changing the monomer feed ratio.This copolymerization reaction provides a simple method for synthesizing degradable functional copolymers from commercially available materials.Hence,it is important not only in polymer chemistry but also in environmental and biomedical engineering.展开更多
A convenient real-time monitoring of monomer concentration during living cationic ring-opening polymerizations of tetrahydrofuran(THF) initiated with methyl triflate(Me OTf) has been developed for kinetic investig...A convenient real-time monitoring of monomer concentration during living cationic ring-opening polymerizations of tetrahydrofuran(THF) initiated with methyl triflate(Me OTf) has been developed for kinetic investigation and determination of equilibrium monomer concentration([M]e) via in situ FTIR spectroscopy in combination with a diamond tipped attenuated total reflectance(ATR) immersion probe. The polymerization rate was first order with respect to monomer concentration and initiator concentration from the linear slope of ln([M]0-[M]e)/([M]-[M]e) versus polymerization time at different temperatures in various solvents. [M]e decreased linearly with initial monomer concentration while increased exponentially with increasing polymerization temperature. The equilibrium also strongly depends on solvent polarity and its interaction with monomer. The equilibrium polymerization time(te) decreased with increasing solvent polarity and decreased linearly with increasing [M]0 in three solvents with different slopes to the same point of bulk polymerization in the absence of solvent. Equation of Mn,e = 72.1/(0.14–0.04[M]e) has been established to provide a simple and effective approach for the prediction for the number-average molecular weight of poly THFs at equilibrium state(Mn,e) in the equilibrium living cationic ring-opening polymerization of THF at 0 °C.展开更多
In this work, a fluorescent monomer 2-(9-carbazolyl) ethyl vinyl ether(CEVE) was synthesized in our lab, and its photo-induced living cationic copolymerization behavior with isobutyl vinyl ether(IBVE) was invest...In this work, a fluorescent monomer 2-(9-carbazolyl) ethyl vinyl ether(CEVE) was synthesized in our lab, and its photo-induced living cationic copolymerization behavior with isobutyl vinyl ether(IBVE) was investigated in detail using diphenyliodonium chloride(DPICl)/2,2-dimethoxy-2-phenylacetophenone(DMPA) and zinc bromide(Zn Br2) initiating system in dichloromethane solution at 5 °C, -5 °C, and -15 °C, respectively. The living nature of this copolymerization system was confirmed by adding fresh comonomer method after the copolymerization almost finished. In addition, the obtained fluorescent copolymer poly(IBVE-co-CEVE) has a low glass transition temperature(Tg), below -10 °C.展开更多
Metal-catalyzed ethylene homopolymerization and ethylene-polar monomer copolymerization to produce new kinds of polyolefins with novel microstructures are of great interest. So far, there are some disadvantages for tr...Metal-catalyzed ethylene homopolymerization and ethylene-polar monomer copolymerization to produce new kinds of polyolefins with novel microstructures are of great interest. So far, there are some disadvantages for traditional transition metal catalyst systems. Therefore, it is critical to develop new catalysts or alternative strategies. In recent years, some cationic [P, O] palladium complexes have been demonstrated with the abilities to obtain oligomers and the high molecular weight polymers. Most importantly, these complexes showed high activity and generated polymers with specific microstructures when used for copolymerization of ethylene with industrially relevant polar monomers. This review summarizes several types of high performance cationic [P, O] palladium catalysts in ethylene oligomerization, ethylene homopolymerization and the copolymerization of ethylene with polar monomers Specially, the regulation of steric and electronic effects at specific sites of the metal complexes was focused.展开更多
From the self-assembly of the typical Salen-type Schiff-base ligand H2L and Zn(OAc)2.2H20 in the molar ratio of 1:1 or 1:2, the mononuclear [Zn(L)(H2O)] (1) or binuclear [Zn2(L)(OAc)2(H2O)] (2) are o...From the self-assembly of the typical Salen-type Schiff-base ligand H2L and Zn(OAc)2.2H20 in the molar ratio of 1:1 or 1:2, the mononuclear [Zn(L)(H2O)] (1) or binuclear [Zn2(L)(OAc)2(H2O)] (2) are obtained, respectively. For both complexes 1 and 2, the unsaturated five-coordinate coordination environment to the catalytic active centers (Zn2+ ions) permits the monomer insertion for the effective solution copolymerization of cyclohexene oxide and maleic anhydride. All the solution copolymerizations afford poly(ester-co-ether)s, while lower catalyst and co-catalyst concentrations are helpful for the formation of alternating polyester. Of the three co-catalysts, 4-(dimethylamino)pyridine is found to be the most efficient, while an excess thereof is detrimental for chain growth of the copolymers.展开更多
A biodegradable ABBA block copolymer was synthesized via the ring-opening co-polymerization of ~ε-caprolactone(CL, B) and glycolide(A) by means of step polymerization in the presence of ethylene glycol as an initiato...A biodegradable ABBA block copolymer was synthesized via the ring-opening co-polymerization of ~ε-caprolactone(CL, B) and glycolide(A) by means of step polymerization in the presence of ethylene glycol as an initiator and stannous octanoate as a catalyst at 110 ℃ for 48 h. The molecular length of the PCL pre-polymer(BB) could be adjusted by controlling the molar ratio of the ethylene glycol initiator to ε-caprolactone monomer. The structure and the composition of the block copolymer were determined by the weight ratio of the monomer glycolide(A) to PCL pre-polymer(BB). The block copolymers were characterized by ~ 1H NMR, GPC, DSC and X-ray. The results confirm the successful synthesis of an ABBA block copolymer.展开更多
文摘Cationic ring-opening copolymerization of 1, 4-anhydro-2, 3-O-isopropylidene-α-D-ribo-pyranose (AIRP) with 1,4-anhydro-2,3-di-O-benzyl-α-D-ribopyranose (ADBR) preparedfrom D-ribose was studied. Copolymerization using SbCl_5 or BF_3 OEt_2 as catalyst atlow temperature gave stereoregular (1→4)β-D-ribofuranan (C-1 and C-4 ring cleavagesee Scheme 1) or (1→5) α-D-ribofuranan (C-1 and C-5 ring cleavage) respectively. Theeffects of catalysts, reaction time and temperatures on yield and stereoregularity of the ob-tained polymers were studied. Polymers were characterized by molecular weight, ~1HNMR,^(13)CNMR and optical rotation.
基金financially supported by the Key Project of Chinese Ministry of Education(No.105075)the National Natural Science Foundation of China(No.20503016).
文摘Cationic ring-opening polymerization of 3,3-bis(chloromethyl)oxacyclobutane catalyzed by BF3.OEt2 was carded out in ionic liquids [bmim]BF4 and [bmim]PF6. The influences of BCMO concentration and molar ratio of BCMO/BF3.OEt2 on the molecular weights and yield of PBCMO were investigated. The polymerization in ionic liquids proceed to high conversions, although molecular weights are limited, similar to polymerization in organic solvent such as CH2Cl2. Follow a viewpoint of green chemistry, we feel ionic liquid [bmim]BF4 is superior to [bmim]PF6. Extracting [bmim]PF6 from the product using organic solvent as extractant limits its advantage as a green reaction media.
文摘The random copolymer poly (1, 3-pentadiene-co-styrene) formed through cationic copolymerization using the ~ethylamine hydrochloride and hydrous aluminium chloride (Et3NHCl-AlCl3) room temperature ionic liquid as initiating agent in toluene was analyzed using IR spectra in conjunction with gel permeation chromatography (GPC). The room temperature ionic liquid was found to have high initiatic activity for copolymerization.
基金Supported by the National Natural Science Foundation of China(Nos.20704036, Key Program 20434020)the State Basic Research Projects of China(No.2005CB623802)
文摘The ring-opening copolymerization of adipic anhydride with propylene oxide was carried out with yttrium triflates as a catalyst. Poly(propylene adipate) could be synthesized by controlling the copolymerization conditions. The copolymerization procedure was tracked by ^1H NMR analyses.
文摘New highly stereoregular 2, 3 -di- O-(p-azidobenzyl )-(1 →5 ) - α-D -ribofuranan was synthesized byselective ring-opening polymerization of 1, 4-anhydro-2, 3 - di-O -(p-azidobenzyl )-α-D -ribopyranose(ADABR) using phosphorus pentafluoride or tin tetrachloride as catalyst at low temperature indichloromethane. The monomer was obtained by the reaction of p - bromomethyl -phenyleneazide with 1, 4 -anhydro-α-D-ribose in DMF. The structure of poly(ADANR) was identified by specific rotation and ^(13)C-NMR spectroscopy. Acid chloride-AgCl_4 complex catalyst such as CH_2=C(CH_3)C^+OClO_4^- used in thepolymerization resulted in polymers with mixed structures, i.e. (1→5)-α-D-ribofuranosidic and (1→4)-β-D-ribopyranosidic units. However, with C_6H_5C^+OClO_4^- as catalyst, pure (1→5)-α-D-ribofuranan was obtained.The effects of catalyst, polymerization temperature and time on polymer stereoregularity were examined, andthe mechanism of the ring-opening polymerization was discussed.
基金supported by The National Natural Science Foundation of China(21504039)。
文摘Recyclable polymers offer a great opportunity to address the environmental issues of plastics.Herein,functionalization of recyclable polymers,poly((R)-3,4-trans six-membered ring-fused GBL)(P((R)-M)),were reported via end-group modifications and block/random copolymerizations.Di-n-butylmagnesium was selected to catalyze ring-opening polymerization(ROP)of(R)-M in the presence of a series of functional alcohols as the initiators.Block/random copolymerizations of(R)-M andε-caprolactone(ε-CL),L-lactide(L-LA)and trimethylene carbonate(TMC)were performed to control the onset decomposition temperature(T_(d)),melting temperature(T_(m))and glass transition temperature(T_(g)).These functionalized recyclable polymers would find broad applications as the sustainable plastics.
基金Supported by the National Nature Science Technology Item of of China(No.2005DC105005-01).
文摘A new quaternary ammonium salt monomer was synthesized and a quaternary amination of lignin( noted as QL), with the monomer was carried out by grafting copolymerization. The products were characterized by Fourier Transform Infrared spectroscopy( FTIR). The experimental results indicate that the yield of the monomer was 99.06%, and the conversion of the monomer and the grafting yield of QL were 93.69% and 185.78%, respectively. The feasibility of QL as the flocculant to be applied in color removal of five artificial dyes, erioehrome black T(dye A), gongo red(dye B ), direct fast black G (dye C ), cuprofix blue green B (dye D ), and acid black ATT (dye E ) was examined. Results show that OL exhihits the favorable flocculation nerformance and high stability.
基金This project was supported by the National Natural Science Foundation of China (No. 20084001).
文摘A series of cyclic (arylene phosphonate) oligomers were prepared by reaction of phenylphosphonic dichloride (PPD) with various bisphenols under pseudo-high dilution conditions via interfacial polycondensation. The yield of cyclic (arylene phosphonate) oligomers is over 85% by using hexadecyltrimethylammoniun bromide as phase transfer catalyst (PTC) at 0 'C . The structures of the cyclic oligomers were confirmed by a combination of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and IR analysis. These cyclic oligomers undergo facile ring-opening polymerization in the melt by using potassium 4,4'-biphenoxide as the initiator to give linear polyphosphonate. Free-radical ring-opening polymerization of cyclic(arylene phosphonate) oligomers containing sulfur linkages was also performed in the melt using 2,2'-dithiobis(benzothiazole) (DTB) as the initiator at 270 °C and the resulting polymer had a Mw, of 8 × 103 with a molecular weight distribution of 4. Ring-opening copolymerization of these cyclic oligomers with cyclic carbonate oligomers was also achieved. The average molecular weight of the resulting copolymer is higher than the corresponding homopolymer and the thermal stability of the copolymer is better than the corresponding homopolymer.
基金This research work was funded by National Key Projects on Basic Research and Development (The "973" Project, No. 2002CB211800).
文摘Two oxetane-derived monomers, 3-(2-cyano-ethoxy)methyl- and 3-(methoxy-(triethylenoxy))methyl-3'- methyloxetane (COX and MTOX), were prepared from 3-hydroxymethyl-3'-methyloxetane. Their homo- and copolymerization in solution were carried out by the cationic ring-opening polymerization with BF3 · Et2O and 1,4-butanediol as co-initiator. The molecular weight and molecular weight distribution were determined using GPC so as to reveal the competition and interchange between active chain end (ACE) and activated monomer (AM) mechanism in the process. The reactivity ratios of the two monomers were calculated according to Kelen-Tudos using ^1H-NMR analysis. The influence of functional side chains in the monomers on the copolymerization behaviors was discussed in virtue of the reactivity ratio data. When doped with lithium salt LiTFSI, the ion conductivity of the homopolymer of MTOX reached 10^-3.58 S/cm at 30℃ and 10^-2.73 S/cm at 80℃, respectively, showing its potential to be used as polymer electrolyte for lithium ion battery.
基金financial support from the National Natural Science Foundation of China(Nos.52222302 and 51973156).
文摘Efficient synthesis of polyester polyols with tunable molecular weight and microstructures from cyclic anhydride/epoxide mixtures by taking advantage of chain transfer reaction remains a great challenge,because most of the catalysts exhibit poor tolerance to chain transfer agent(CTA).In this contribution,we demonstrated that potassium acetate(KOAc)and 18-crown-6(18-C-6)combination has great potential in the synthesis of diverse polyester polyols with controllable molecular weight and high-end group fidelity.Com-pared with KOAc,KOAc/18-C-6 pair could induce a much faster chain transfer between the active and dormant chains,and thus produce polyester polyols with narrow and monomodal distribution.In addition,polyester polyols could be efficiently prepared in laboratory by using commercially available cyclic anhydride without further purification(containing about 2%diacid residual as CTA)with an extremely low catalyst loading([catalyst pair]:[anhydride]:[epoxide]=1:50000:250000,[catalyst pair]=0.0004 mol%).KOAc/18-C-6 could also promote the self-switchable copolymerization of cyclic anhydride/epoxide/cyclic ester mixtures.Ring-opening copolymerization of cyclic ester was initiated automatically after the full conversion of cyclic anhydride,finally producing polyester polyols with ABA-type block structure.
基金the financial support of National Key Fundamental Research Program of China (Grant No. G1999064703) the National Natural Science Foundation of China (Grant No. 20104005).
文摘Amphiphilic copolymer of 5-benzyloxytrimethylene carbonate (BTMC) with poly (vinyl pyrrolidone) (PVP) was successfully synthesized using immobilized porcine pancreas lipase (IPPL) or SnOct2 as catalyst. Hydroxyl terminated PVP, synthesized with 2-mercaptoethanol as a chain transfer reagent, was employed as a rnacroinitiator. The resulting copolymers were characterized by GPC, ^1H NMR and IR. Increasing the BTMC/PVP-OH feed ratio ([B]/[P]) resulted in the increase of Mn of corresponding copolymers and the decrease of Mw/Mn. Immobilized enzyme has comparable catalytic activity to SnOct2 for the copolymerization.
基金supported by the National Natural Science Foundation of China(Nos.20774008,20934001)Program for Changjiang Scholars and Innovative Research Team in Universities(IRT0706)
文摘The copolymerization of 4-vinylbenzyl chloride (VBC) and vinyl acetate (VAC) was carried out in toluene at 75℃ via radical polymerization using 2,2'-azo-bis-(isobutyronitrile) (AIBN) as an initiator. The random copolymers of poly(4-vinylbenzyl chloride-co-vinyl acetate) (P(VBC-co-VAC)) with number average molecular weight (Mn) from 2000 to 6900, relatively narrow molecular weight distribution (MWD, Mw/Mn ca. 2.0) and with different copolymer composition of 4-vinylbenzyl chloride (VBC) from 17 mol% to 62 mol% could be obtained. The P(VBC-co-VAC) copolymers with an average number of 7 to 13 initiating sites of benzyl chloride per macromolecule could be used for the cationic polymerization of isobutylene (IB). The cationic polymerizations of IB were further conducted by using P(VBC-co-VAC) copolymers as macroinitiators in conjunction with TICl4 at -40℃ in CH2Cl2. The effects of VBC/TiCl4 (molar ratio) on monomer conversion, Mn and MWD of the resultant copolymers were investigated under 3 sets of conditions. It is found that P(VBC-co-VAC)-g-PIB copolymers with relatively narrow MWD (Mw/Mn ca. 2.0) and with terminal tert-chlorine functional groups in branched PIB chains could be successfully synthesized when VBC/TiCl4 (molar ratio) was set in the range from 0.10 to 1.12. The unimodal GPC curve of the P(VBC-co-VAC)-g-PIB copolymers by RI detector was almost in harmony with the GPC curve by UV detector. The TEM image of the P(VBC-co-VAC)-g-PIB copolymer stained by RuO indicated that the copolymer formed a two-phase morphology with P(VBC-co-VAC)-rich domains of 20-100 um in size tethered by PIB branch segments.
基金supported by the Ministry Basic Research Found(No.51412010204BQ0161).
文摘A kind of novel triblock copolymers of poly(γ-benzyl L-glutamate)-b-poly(tetrahydrofuran)-b-poly(γ-benzyl L-glutamate)s(PBLG-b-PTHF-b-PBLG)was synthesized by using bis(3-aminopropyl)terminated polytetrahydrofuran to initiate the ring-opening polymerization ofγ-benzyl L-glutamate N-carboxyanhydride(BLG-NCA).The corresponding multiblock poly(amino acid-urea)s were prepared in one-pot protocol from the chain extension of PBLG-b-PTHF-b-PBLG with MDI.The resulting triblock and multiblock copolymers were characterized by FTIR,~1H-NMR,^(13)C-NMR and GPC techniques.It is demonstrated that the chain extension has taken place to give rise to the copolymers with the well-defined block composition and narrow molecular weight distribution.A distinct T_g arising from the hard-segments was observed in all the copolymers.Their mechanical properties showed an increasing trend with the molecular weight enhancement of the prepolymers.
文摘Styrene-isoprene-styrene(SIS) block copolymer was modified into epoxidized styrene-isoprene-styrene(ESIS) block copolymer with performic acid generated in situ from hydrogen peroxide and formic acid.The structure and property of ESIS were characterized by Fourier transform infrared(FT-IR) spectroscopy,gel permeation chromatography(GPC),thermogravimetric/differential thermogravimetric(TG/DTG),melt flow rate(MFR) and dynamic mechanical analysis(DMA),and the reaction mechanism in the process of epoxidation was analyzed.The results showed that C=C double bonds of 1,4-structure were more active than that of 3,4-structure in polyisoprene chains.With epoxidation reaction proceeding,the whole tendency of molecular weight increased and molecular weight distribution widened,and MFR firstly increased and latterly decreased.The heat resistance of ESIS was superior to that of SIS.When SIS was changed into ESIS with 15.3% of mass fraction of epoxide groups,Tg of polyisoprene chains increased from-45.3 ℃ to 10.9 ℃.In the earlier period of epoxidation,some molecular chains ruptured and new substances with low molecular weight formed.However,in the latter period,crosslinking reaction between molecular chains which was initiated by epoxide groups or C=C double bonds occurred and crosslinked insoluble substances came into being.
基金financially supported by the Natural Science Foundation for Excellent Young Scholar of Jiangsu Province (No. BK20170056)the National Natural Science Foundation of China(No. 21304010)+1 种基金the Opening Project of Key Laboratory of Polymer Processing Engineering (South China University of Technology)Ministry of Education, and the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)
文摘Phosphazene base,t-BuP2,was employed to catalyze the proton transfer polymerization(PTP)of 2-hydroxyethyl acrylate(HEA),and PTP was further combined with ring-opening polymerization(ROP)to exploit a new type of hybrid copolymerization.The studies on homopolymerization showed that t-BuP2 was a particularly efficient catalyst for the polymerization of HEA at room temperature,giving an excellent monomer conversion.Throughout the polymerization,transesterification reactions were unavoidable,which increased the randomness in the structures of the resulting polymers.The studies on copolymerization showed that t-BuP2 could simultaneously catalyze the hybrid copolymerization via the combination of PTP and ROP at 25°C.During copolymerization,HEA not only provided hydroxyl groups to initiate the ROP ofε-caprolactone(CL)but also participated in the polymerization as a monomer for PTP.The copolymer composition was approximately equal to the feed ratio,demonstrating the possibility to adjust the polymeric structure by simply changing the monomer feed ratio.This copolymerization reaction provides a simple method for synthesizing degradable functional copolymers from commercially available materials.Hence,it is important not only in polymer chemistry but also in environmental and biomedical engineering.
基金financially supported by the National Natural Science Foundation of China(Nos.51173008 and 51221002)
文摘A convenient real-time monitoring of monomer concentration during living cationic ring-opening polymerizations of tetrahydrofuran(THF) initiated with methyl triflate(Me OTf) has been developed for kinetic investigation and determination of equilibrium monomer concentration([M]e) via in situ FTIR spectroscopy in combination with a diamond tipped attenuated total reflectance(ATR) immersion probe. The polymerization rate was first order with respect to monomer concentration and initiator concentration from the linear slope of ln([M]0-[M]e)/([M]-[M]e) versus polymerization time at different temperatures in various solvents. [M]e decreased linearly with initial monomer concentration while increased exponentially with increasing polymerization temperature. The equilibrium also strongly depends on solvent polarity and its interaction with monomer. The equilibrium polymerization time(te) decreased with increasing solvent polarity and decreased linearly with increasing [M]0 in three solvents with different slopes to the same point of bulk polymerization in the absence of solvent. Equation of Mn,e = 72.1/(0.14–0.04[M]e) has been established to provide a simple and effective approach for the prediction for the number-average molecular weight of poly THFs at equilibrium state(Mn,e) in the equilibrium living cationic ring-opening polymerization of THF at 0 °C.
基金supported by the National Natural Science Foundation of China(Nos.21174096,21274100 and 21234005)the Project of International Cooperation of the Ministry of Science and Technology of China(No.2011DFA50530)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘In this work, a fluorescent monomer 2-(9-carbazolyl) ethyl vinyl ether(CEVE) was synthesized in our lab, and its photo-induced living cationic copolymerization behavior with isobutyl vinyl ether(IBVE) was investigated in detail using diphenyliodonium chloride(DPICl)/2,2-dimethoxy-2-phenylacetophenone(DMPA) and zinc bromide(Zn Br2) initiating system in dichloromethane solution at 5 °C, -5 °C, and -15 °C, respectively. The living nature of this copolymerization system was confirmed by adding fresh comonomer method after the copolymerization almost finished. In addition, the obtained fluorescent copolymer poly(IBVE-co-CEVE) has a low glass transition temperature(Tg), below -10 °C.
基金Acknowledgement This work was supported by the National Natural Science Foundation of China (NSFC, No. 21304054), the Taishan Scholar Foundation, Foundation of Qufu Normal University (No. xkJ201603), and the National College Students Innovation Project (No. 201610446029).
文摘Metal-catalyzed ethylene homopolymerization and ethylene-polar monomer copolymerization to produce new kinds of polyolefins with novel microstructures are of great interest. So far, there are some disadvantages for traditional transition metal catalyst systems. Therefore, it is critical to develop new catalysts or alternative strategies. In recent years, some cationic [P, O] palladium complexes have been demonstrated with the abilities to obtain oligomers and the high molecular weight polymers. Most importantly, these complexes showed high activity and generated polymers with specific microstructures when used for copolymerization of ethylene with industrially relevant polar monomers. This review summarizes several types of high performance cationic [P, O] palladium catalysts in ethylene oligomerization, ethylene homopolymerization and the copolymerization of ethylene with polar monomers Specially, the regulation of steric and electronic effects at specific sites of the metal complexes was focused.
基金financially supported by the National Natural Science Foundation of China(Nos.91222201,21173165 and 20871098)the Program for New Century Excellent Talents in Universities from the Ministry of Education of China(No.NCET-10-0936)+4 种基金the State Key Laboratory of Structure Chemistry(20100014)the Provincial Natural Foundation(2011JQ2011) of Shaanxithe Education Committee Foundation of Shaanxi Province(11JK0588,12JK0577)Graduate Innovation and Creativity Fund(YZZ12038) of Northwest UniversityHong Kong Research Grants Council(HKBU 202407 and FRG/06-07/II-16)
文摘From the self-assembly of the typical Salen-type Schiff-base ligand H2L and Zn(OAc)2.2H20 in the molar ratio of 1:1 or 1:2, the mononuclear [Zn(L)(H2O)] (1) or binuclear [Zn2(L)(OAc)2(H2O)] (2) are obtained, respectively. For both complexes 1 and 2, the unsaturated five-coordinate coordination environment to the catalytic active centers (Zn2+ ions) permits the monomer insertion for the effective solution copolymerization of cyclohexene oxide and maleic anhydride. All the solution copolymerizations afford poly(ester-co-ether)s, while lower catalyst and co-catalyst concentrations are helpful for the formation of alternating polyester. Of the three co-catalysts, 4-(dimethylamino)pyridine is found to be the most efficient, while an excess thereof is detrimental for chain growth of the copolymers.
文摘A biodegradable ABBA block copolymer was synthesized via the ring-opening co-polymerization of ~ε-caprolactone(CL, B) and glycolide(A) by means of step polymerization in the presence of ethylene glycol as an initiator and stannous octanoate as a catalyst at 110 ℃ for 48 h. The molecular length of the PCL pre-polymer(BB) could be adjusted by controlling the molar ratio of the ethylene glycol initiator to ε-caprolactone monomer. The structure and the composition of the block copolymer were determined by the weight ratio of the monomer glycolide(A) to PCL pre-polymer(BB). The block copolymers were characterized by ~ 1H NMR, GPC, DSC and X-ray. The results confirm the successful synthesis of an ABBA block copolymer.