Synthesis and Reactivity of Hydroxypoly(ethylene oxide) propyl–b–polydimethylsiloxane–b–propyl hydroxypoly(ethylene oxide)

A series of α, ω–bishydroxyl terminated PDMS, hydroxypoly(ethylene oxide) propyl–b–polydimethylsiloxane–b–propyl hydroxypoly(ethylene oxide) (HPEO–PDMS–HPEO) was prepared by a hydrosilation reaction of monoallyloxy substituted poly(ethylene oxide) with α,ω–bishydrogen terminated PDMS (HPDMS) that obtained via acid–catalyzed ring–opening polymerization of octamethylcyclotetrasiloxane with 1,1,3,3–tetramethyldisiloxane. Chloroplatinic acid was employed as the catalyst of hydrosilation. The molecular weight of HPEO–PDMS–HPEO could be controlled easily by varying the chain length of HPDMS. FTIR and ¹H–NMR spectroscopy were used to identify the structure of HPEO–PDMS–HPEO and HPDMS. The conversion of Si–H bond to Si–C bond was affected by the catalyst amount, reaction time and temperature. It was found that the optimum condition of hydrosilation reaction was the catalyst amount of 22 μg/g and 5 h time at 100°C. Synthesized HPEO–PDMS–HPEO showed good storage stability at ambient temperature. Urethane reaction of OH and NCO group revealed that HPEO–PDMS–HPEO was more reactive toward to diisocyanate than α, ω –bishydroxylbutyl terminated PDMS.     

3‐miktoarm star terpolymers using triple click reactions: Diels–Alder,copper‐catalyzed azide‐alkyne cycloaddition,and nitroxide radical coupling reactions

Well‐defined linear furan‐protected maleimide‐terminated poly(ethylene glycol) (PEG‐MI), tetramethylpiperidine‐1‐oxyl‐terminated poly(ε‐caprolactone) (PCL‐TEMPO), and azide‐terminated polystyrene (PS‐N₃) or ‐poly(N‐butyl oxanorbornene imide) (PONB‐N₃) were ligated to an orthogonally functionalized core ( 1 ) in a two‐step reaction mode through triple click reactions. In a first step, Diels–Alder click reaction of PEG‐MI with 1 was performed in toluene at 110 °C for 24 h to afford α‐alkyne‐α‐bromide‐terminated PEG (PEG‐alkyne/Br). As a second step, this precursor was subsequently ligated with the PCL‐TEMPO and PS‐N₃ or PONB‐N₃ in N,N‐dimethylformamide at room temperature for 12 h catalyzed by Cu(0)/Cu(I) through copper‐catalyzed azide‐alkyne cycloaddition and nitroxide radical coupling click reactions, yield resulting ABC miktoarm star polymers in a one‐pot mode. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

THE STEREOSELECTIVE SYNTHESIS OF N-ARYL-TRANS,TRANS-α-CARBOXYL-β-METHOXYCARBONYL-γ-ARYL-γ-BUTYROLACTAMS

Cis-1-methoxycarbonyl-2-aryl-6,6-dimethyl-5,7-diox-spiro-[2,5]-4,8-octadiones (1) in dimethyl ethylene glycol at room temperature react with anilines (2) to give N-aryl-trans,trans-α-carboxyl-β-methoxycarbonyl-γ-aryl-γ-butyrolactams (3) in good to excellent yields and high stereoselectivity.     

Ion conductivity studies of blends of poly(methyl methacrylate)-g-poly(ethylene glycol) and poly(ethylene glycol) complexed with LiCF3 SO3

Polymer electrolytes which are adhesive, transparent, and stable to atmospheric moisture have been prepared by blending poly(methyl methacrylate)-g-poly(ethylene glycol) with poly(ethylene glycol)/LiCF₃ SO₃ complexes. The maximum ionic conductivities at room temperature were measured to be in the range of 10⁻⁴ to 10⁻⁵ s cm⁻¹. The clarity of the sample was improved as the graft degree increased for all the samples studied. The graft degree of poly(methyl methacrylate)-g-poly(ethylene glycol) was found to be important for the compatibility between the poly(methyl methacrylate) segments in poly(methyl methacrylate)-g-poly(ethylene glycol) and the added poly(ethylene glycol), and consequently, for the ion conductivity of the polymer electrolyte. These properties make them promising candidates for polymer electrolytes in electrochromic devices. © 1996 John Wiley & Sons, Inc.     

Novel synthesis of biodegradable amphiphilic linear and star block copolymers based on poly(ε‐caprolactone) and poly(ethylene glycol)

Biodegradable, amphiphilic, diblock poly(ε‐caprolactone)‐block‐poly(ethylene glycol) (PCL‐b‐PEG), triblock poly(ε‐caprolactone)‐block‐poly(ethylene glycol)‐block‐poly(ε‐caprolactone) (PCL‐b‐PEG‐b‐PCL), and star shaped copolymers were synthesized by ring opening polymerization of ε‐caprolactone in the presence of poly(ethylene glycol) methyl ether or poly(ethylene glycol) or star poly(ethylene glycol) and potassium hexamethyldisilazide as a catalyst. Polymerizations were carried out in toluene at room temperature to yield monomodal polymers of controlled molecular weight. The chemical structure of the copolymers was investigated by ¹H and ¹³C NMR. The formation of block copolymers was confirmed by ¹³C NMR and DSC investigations. The effects of copolymer composition and molecular structure on the physical properties were investigated by GPC and DSC. For the same PCL chain length, the materials obtained in the case of linear copolymers are viscous whereas in the case of star copolymer solid materials are obtained with low T_g and T_m temperatures. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3975–3985, 2007     

V‐shaped graft copolymers via triple click reactions: Diels–alder,copper‐catalyzed azide–alkyne cycloaddition,and nitroxide radical coupling

We report here a simple and universal synthetic pathway covering triple click reactions, Diels–Alder, copper‐catalyzed azide–alkyne cycloaddition (CuAAC), and nitroxide radical coupling (NRC), to prepare well‐defined graft copolymers with V‐shaped side chains. The Diels–Alder click reaction between the furan protected‐maleimide‐terminated poly(ethylene glycol) (PEG) and a trifunctional core ( 1 ) carrying an anthracene, alkyne, and bromide was carried out to yield the corresponding α‐alkyne‐ and α‐bromide‐terminated PEG (PEG‐alkyne/Br) in toluene at 110 °C. Subsequently, the polystyrene or polyoxanorbornene with pendant azide functionality as a main backbone is reacted with the PEG‐alkyne/Br and 2,2,6,6‐tetramethyl‐1‐piperidinyloxy (TEMPO)‐terminated poly(ε‐caprolactone) using the CuAAC and NRC reactions in a one‐pot fashion in N,N′‐dimethylformamide at room temperature to result in the target V‐shaped graft copolymers. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4667–4674     

Heterograft brush copolymers via romp and triple click reaction strategies involving CuAAC,diels–alder,and nitroxide radical coupling reactions

In this study, an equimolar mixture of oxanorbornenyl‐anthracene (ONB‐anthracene), oxanorbornenyl‐bromide (ONB‐Br), and oxanorbornenyl tosylate (ONB‐OTs) was polymerized via ring opening metathesis polymerization using the first generation Grubbs' catalyst in CH₂Cl₂ at room temperature to form poly(ONB‐anthracene‐co‐ONB‐Br‐co‐ONB‐OTs)₁₀ copolymer as a main backbone. Next, this main backbone was sequentially clicked with a furan protected maleimide‐terminated poly(methyl methacrylate), 2,2,6,6‐tetramethyl‐1‐piperidinyloxy‐terminated poly(ethylene glycol), and alkyne‐terminated poly(ε‐caprolactone) (PCL₂₀‐alkyne) via Diels–Alder, nitroxide radical coupling, and copper‐catalyzed azide‐alkyne cycloaddition, respectively, to yield a poly(ONB‐g‐PMMA‐co‐ONB‐g‐PEG‐co‐ONB‐g‐PCL)₁₀ heterograft brush copolymer © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Synthesis and characterization of some new Schiff base polymers

Seven Schiff base polymers poly 5,5^′-methylenebis(2-hydroxyacetophenone)semicarbazone (PHASC), poly-5,5^′-methylenebis(2-hydroxyacetophenone)thiosemicarbazone (PHATS), poly 6,6^′-methylenebis(2-hydroxynaphthaldehyde)1,2-propylenediimine (PHNPn), poly 6,6^′-methylenebis (2-hydroxynaphthaldehyde)1,3-propylenediimine (PHNPR), poly 6,6^′-methylenebis (2-hydroxy-naphthaldehyde)thiosemicarbazone (PHNTS), poly 6,6^′-methylenebis(2-hydroxy-naphthaldehyde)urea (PHNU) and poly-6,6^′-methylenebis(2-hydroxynaphthaldehyde)semicarbazone (PHNSC) were prepared by polycondensation of 5,5^′-methylenebis(2-hydroxyacetophenone) (MHA) or 6,6^′-methylenebis(2-hydroxynaphthaldehyde) (MHN) with semicarbazide, thiosemicarbazide, 1,2-propylenediamine, 1,3-propylenediamine or urea. The polymers were characterized by elemental micro-analysis, infrared and ultraviolet spectroscopy and viscosity measurements. The reduced viscosity of the polymers measured in dimethylformamide (DMF) was observed in the range 0.32-0.63 dl/g.     

Functionalized polymers with metal complexing segments: a simple and high‐yield entry towards 2,2′:6′,2″‐terpyridine‐based oligomers

Williamson type ether reactions were utilized for a high yield reaction of 4′‐chloro‐2,2′:6′,2″‐terpyridine with α,ω‐dihydroxy‐functionalized poly(ethylene oxide) and poly(oxytetramethylene)s to obtain bis(terpyridine)‐terminated telechelics. The completeness of the functionalization was proven by NMR spectroscopy, GPC and MALDI‐TOF‐MS investigations. The addition of transition metal ions resulted in a polyaddition polymerization leading to the formation of extended metallo‐supramolecular polymers, as proven by UV/VIS spectroscopy titration experiments.     

Photo‐responsive amphiphilic poly(α‐hydroxy acids) with pendent o‐nitrobenzyl ester constructed via copper‐catalyzed azide‐alkyne cycloaddition reaction

Photo‐responsive block copolymer mPEG‐b‐poly(Tyr)‐g‐NB was prepared by introduction of o‐nitrobenzyl ester group into the side chain of amphiphilic poly(ethylene glycol)‐b‐poly(α‐hydroxy acids) (mPEG‐b‐poly(Tyr)) containing pendent alkynyl group via copper‐catalyzed azide‐alkyne cycloaddition reaction. The amphiphilic mPEG‐b‐poly(Tyr) was synthesized via the ring‐opening polymerization of O‐carboxyanhydrides, with monomethoxy poly(ethylene glycol) (mPEG) as macroinitiator. The molecular structure, self‐assembly, and photo‐controlled release of the obtained mPEG‐b‐poly(Tyr)‐g‐NB were thoroughly investigated. mPEG‐b‐poly(Tyr)‐g‐NB could self‐assemble into spherical micelles in water and showed disassembly under UV light irradiation, which was demonstrated by means of UV‐vis spectroscopy, scan electron microscopes, and dynamic light scattering measurement. Fluorescence emission measurements demonstrated that Nile red, encapsulated by micelles, can be released upon UV irradiation. This study provides a convenient way to construct smart poly(α‐hydroxy acids)‐based nanocarriers for controlled release of hydrophobic drugs. Copyright © 2015 John Wiley & Sons, Ltd.     

聚醚链段长度对氨基聚醚-环氧树脂力学性能的影响

以柔性端氨基聚醚(BATPE)和双酚A环氧树脂(DGEBA)为原料, 制备了无微相分离结构的无定型AB交联热固性树脂. 测试了3种不同聚乙二醇(PEG)链段长度(M_PE)的BATPE-DGEBA环氧树脂固化产物的应力-应变曲线、动态力学温度谱和冲击断面形貌. 结果表明, 在环氧树脂交联网络中引入两端与DGEBA化学连接的PEG链段能避免微相分离结构的生成, 有利于提高DGEBA链段的应变松弛速率. 增加M_PE, 一方面能降低环氧树脂固化产物的玻璃化转变温度和室温下的刚度和拉伸强度, 增加韧性(包括冲击强度和拉伸韧性)、断裂应变和模量损耗因子; 另一方面也能提高固化产物在低温下的储存模量. 优化M_PE可制备出在中低温下同时具有优异的拉伸强度、模量、断裂应变和冲击性能的BATPE-DGEBA环氧树脂.     

One-pot synthesis of macrocyclic compounds possessing two cyclobutane rings by sequential inter- and intramolecular [2+2] photocycloaddition reactions

Sensitized photocycloaddition reactions of 6,6′-dimethyl-4,4′-[1,3-bis(methylenoxy)phenylene]-di-2-pyrone (1) with electron-poor α,ω-diolefins such as ethylene diacrylate (2a) and polyoxyethylene dimethacrylates (2b-d) afforded site- and stereoselective macrocyclic dioxatetralactones (3a-d) and (4b) having 18- to 25-membered rings across the C5-C6 and C5′-C6′ double bonds, or C5-C6 and C3′-C4′ double bonds in 1, respectively. Similar photoreactions of 1 with electron-rich α,ω-diolefins such as poly(ethylene glycol)divinyl ether (2e and 2f) afforded crown ether-type macrocyclic compounds (5e and 5f) having 18- and 21-membered rings across the C3-C4 and C3′-C4′ double bonds in 1, respectively. The stereochemical features of 3b, 5e-xx, and 5e-nn were determined by the X-ray crystal analysis. The reaction mechanism was inferred by MO methods.     

Amino-terminated poly(ethylene glycol) as the initiator for the ring-opening polymerization of 3-methylmorpholine-2,5-dione

Block copolymers with poly[3-methylmorpholine-2,5-dione] (PMMD) and poly[ethylene glycol] (PEG) blocks, PMMD-b-PEG-b-PMMD, were synthesized via ring-opening polymerization of 3-methylmorpholine-2,5-dione with amino-terminated PEG as the initiator at 140 °C within 10 h. Three kind of amino terminated PEG with different average molecular weight were used. The block copolymer was amorphous and the glass transition temperature decreased with increase of PEG block in the copolymer.     

Facile synthesis of poly(l‐tryptophan) through polycondensation of activated urethane derivatives

A facile and phosgene‐free synthetic route to poly(l ‐tryptophan) 2 by the polycondensation of N‐phenoxycarbonyl‐l ‐tryptophan 1 is described. The monomer 1 was synthesized via the carbamylation of tetrabutylammonium salt of L‐tryptophan with diphenyl carbonate. The polycondensation proceeded smoothly at 60 °C in N,N‐dimethylacetamide in the presence of amines (n‐butylamine, diethylamine, and triethylamine) along with the elimination of phenol and carbon dioxide. The structural analysis of the obtained 2 by Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry revealed that n‐butylamine or diethylamine was successfully incorporated into the chain end of the polypeptide. Furthermore, we have demonstrated the synthesis of a diblock copolymer by utilizing amine‐terminated poly(ethylene glycol) as a source of the polyether segment. The chain length of the polypeptide segment was controlled by varying feed ratio between 1 and the amino group of poly(ethylene glycol). © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4565–4571     

Diels‐alder click reaction for the preparation of polycarbonate block copolymers

The Diels‐Alder reaction as a click reaction strategy is applied to the preparation of well‐defined polycarbonate (PC)‐block copolymers. A well‐defined α‐anthracene‐terminated polycarbonate (PC‐anthracene) is prepared using 9‐anthracene methanol as an initiator in the ring opening polymerization of benzyl 5‐methyl‐2‐oxo‐1,3‐dioxane‐5‐carboxylate in CH₂Cl₂ at room temperature for 5 h. Next, a well‐defined α‐furan protected maleimide‐terminated‐poly(ethylene glycol) (PEG₁₁‐MI or PEG₃₇‐MI), ‐poly(methyl methacrylate) (PMMA₂₆‐MI), and ‐poly(ε‐caprolactone) (PCL₂₇‐MI) were clicked with the PC‐anthracene at reflux temperature of toluene to yield their corresponding PC‐based block copolymers (PC‐b‐PEG, PC‐b‐PMMA, and PC‐b‐PCL). The homopolymer precursors and their block copolymers were characterized by using the GPC, NMR and UV analysis. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Efficient bimetallic titanium catalyst for carbonyl-ene reaction

A new family of achiral 3,3′,5,5′-tetrasubstituted-2,2′,6,6′-tetrahydroxy biphenyl ligand 4 was developed. The axial chirality of the ligand could be induced by the chelation of 2,2′,6,6′-tetrahydroxy groups with (R)-BINOL-Ti(OⁱPr)₂ to form an axially chiral bimetallic titanium catalyst 9. Compared with (R)-BINOL-Ti(OⁱPr)₂ catalyst, this novel catalyst 9 exhibited excellent activity and enantioselectivity for the carbonyl-ene reaction of methylstyrene and ethyl glyoxylate. 3,3′,5,5′-Tetrasubstituted groups showed a remarkable effect on both enantioselectivity and yield. With 9d prepared from 3,3′,5,5′-tetramethyl-2,2′,6,6′-tetrahydroxy biphenyl 4d as the catalyst, the best result, up to 97.6% ee and 99% yield, was obtained. Additionally, the bimetallic catalyst 9 also showed better catalytic capability than the corresponding monometallic catalyst.     

Hierarchically organized micellization of thermoresponsive rod‐coil copolymers based on poly[oligo(ethylene glycol) methacrylate] and poly(ε‐caprolactone)

A series of amphiphilic triblock copolymers, poly[oligo(ethylene glycol) methacrylate]_x‐block‐poly(ε‐caprolactone)‐block‐poly[oligo(ethylene glycol) methacrylate]_x, POEGMA_Co(x), were synthesized. Formation of hydrophobic domains as cores of the micelles was studied by fluorescence spectroscopy. The critical micelle concentrations in aqueous solution were found to be in the range of circa 10^?6 M. A novel methodology by modulated temperature differential scanning calorimetry was developed to determine critical micelle temperature. A significant concentration dependence of cmt was found. Dynamic light scattering measurements showed a bidispersed size distribution. The micelles showed reversible dispersion/aggregation in response to temperature cycles with lower critical solution temperature between 75 and 85 °C. The interplay of the two hydrophobic and one thermoresponsive macromolecular chains offers the chance to more complex morphologies. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

AGET ATRP of methyl methacrylate with poly(ethylene glycol) (PEG) as solvent and TMEDA as both ligand and reducing agent

Activator generated by electron transfer atom transfer radical polymerization of methyl methacrylate (MMA) in inexpensive, non-toxic poly(ethylene glycol) (PEG), with air-stable Cu(II)X₂(X = Br, Cl) as the catalyst and N,N,N′,N′-tetramethylethylenediamine (TMEDA) as both ligand and reducing agent was investigated. The polymerizations in PEG proceeded in a well-controlled manner as evidenced by kinetic studies and chain extension results. The polydispersity of the polymer obtained was quite narrow, with a weight-average molecular weight/number-average molecular weight ratio of less than 1.2. Effects of the TMEDA content and the catalysts on polymerization were also investigated, respectively.     

Synthesis of networked polymers by copolymerization of monoepoxy‐substituted lithium sulfonylimide and diepoxy‐substituted poly(ethylene glycol), and their properties

Networked polymers that had poly(ethylene glycol) (PEG) chains and lithium sulfonylimide salt structures were prepared by curing a mixture of poly(ethylene glycol) diglycidyl ether and lithium 3‐glycidyloxypropanesulfonyl‐trifluoromethanesulfonylimide with poly(ethylene glycol) bis(3‐aminopropyl) terminated. The obtained flexible self‐standing networked polymer films showed high thermal and mechanical stability with relatively high ionic conductivity. The room temperature ionic conductivity under a dry condition was in the range of 10^?5 ～ 10^?4 S m^?1, which is one order of magnitude higher than the corresponding networked polymers having lithium sulfonate salt structures (10^?6 ～ 10^?5 S m^?1). The film sample became swollen by immersing in propylene carbonate (PC) or PC solution of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The sample swollen in PC showed higher ionic conductivity (7.2 × 10^?3 S m^?1 at room temperature), and the sample swollen in 1.0 M LiTFSI/PC showed much higher ionic conductivity (8.2 × 10^?1 S m^?1 at room temperature). © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011