Synthesis and Antibacterial Activity of Selenium-functionalized Poly(ε-caprolactone)

A selenium-functionalizedε-caprolactone was synthesized by introducing a phenyl selenide group at the 7-position.A polymer was obtained through the ring-opening polymerization of this monomer in a base/thiourea binary organocatalytic system.A living polymerization process was achieved under mild conditions.The resulting polymers had a controlled molecular weight with a narrow molecular weight distributions and high end-group fidelity.Random copolymers could be obtained by copolymerizing this monomer withε-caprolactone.The thermal degradation temperature of the obtained copolymers decreased with the increasing molar ratio of selenide functionalized monomer in copolymers,while the glass transition temperature increased.In addition,the phenyl selenide side group could be further modified to a polyselenonium salt,which resulted in a polymer with good antibacterial properties.The survival rate of E.coli and S.aureus was only 9%with a polymer concentration of 62.5μg/mL.     

Photo-polymerization of liquid crystalline monomer in oriented liquid crystal phase

<正>A new approach to synthesize liquid crystalline polymer with narrow polydispersity index(PDI) was developed.Photopolymerization of 4-cyanophenyl-4'-(6-acryloyloxyhexyloxy)benzoate(RM23) in nematic liquid crystals with macroscopic orientation was studied.The effects of the monomer concentration on the molecular weight and PDI of the resulting polymers were studied through gel permeation chromatography(GPC) and polarized optical microscopy.The low PDI of 1.19 and 1.22 was obtained in the reverse and normal modes,respectively.The PDI and molecular weight increased with monomer concentration.     

NOVEL HYPERBRANCHED POLY（PHENYLENE OXIDE）S WITH PHENOLIC TERMINAL GROUPS： EFFECTS OF REACTION TIME AND CORE MOLECULES ON THE MOLECULAR WEIGHT AND POLYDISPERSITY

A novel hyperbranched poly（phenylene oxide） （HPPO） with phenolic terminal groups was prepared from 4-bromo-4＇,4＂-dihydroxytriphenylmethane as AB2 monomer in dimethylsulfoxide （DMSO） via a modified Ullmann reaction. The molecular weight and polydispersity （PD） of the resulting polymers increased with increasing reaction time. In the presence of core molecules （bisphenol A and 1,3,5-trihydroxybenzene）, which have the similar molecular backbones to the reactive monomer, the molecular weight could be controlled by varying the core-to-monomer ratio. Incorporation of a very small amount of core molecules could lead to a higher molecular weight as compared with that without the addition of core molecules. However, when the core content reached certain extent, the molecular weight would decrease with the further increase in the core content. A new similar behavior of control over the PD was also obtained. The resulting polymers were characterized by ^1H-NMR, ^13C-NMR, FT-IR, and GPC.     

Microemulsion Polymerization of Methyl Methacrylate

The microemulsion polymerization of methyl methacrylate was studied. The effects of feeding modes on the structure and the properties of the obtained polymer microlatex were investigated by measuring the conversion, the transmittance and the refractive index of the latex, and by measuring the particle size, the molecular weight and the glass transition temperature (T_g) of the polymers. The results show that compared to the batch feeding mode, the semi-continuous feeding mode is more favorable to form a PMMA microlatex with a higher transmittance, a smaller particle size, a higher molecular weight and a higher T_g. And the obtained PMMA microlatex has a 30％—40％ (mass fraction) polymer content, a 0. 03 emulsifier/water weight ratio, a 0. 05 emulsifier/monomer weight ratio and a 17 nm average particle diameter, which is very important for the industrialization of the microemulsion polymerization technique.     

An alternating copolymer of maleimide and atropic acid with narrow molecular weight distribution prepared by radical mechanism

Three basic conditions for preparation of alternating copolymer with narrow molecular weight distribution were derived from the element kinetic equations of binary radical copolymerization. Using maleimide (MI) and atropie acid (ATA) as model monomer pairs and dioxane as the solvent the alternating copolymer with molecular weight distribution in the range of 1.09--1.20 was prepared successfully by charger transfer complex (CTC) mechanism in the presence of benzoyl peroxide at 85℃. The monomer reactivity ratioes r_1(MI)=0.05±0.01 and r_2(ATA)=0.03±0.02 were measured. The alternating eopolymerization was carried out through formation of a contact-type CTG and then alternating addition of MI and ATA monomers. The molecular weight of the copolymers is nearly independent of the feed ratio in a large range and the polymerization rate dropped with an increase in ATA in feed ratio.     

Unprecedented synthesis of chiral calix[4](aza)crowns and its potent encapsulating methanol

Unprecedented synthesis of chiral (aza)crown ethers of calix[4]arene derivatives bearing a carboxyl amide bridge was described. The synthesis proceeds through condensation of the corresponding dinitriles with optically active 1,2-aminoalcohols,and is catalyzed by the ZnCl2 Lewis acid at elevated temperature in a very efficient one-pot process. The cavity of calix[4](aza)crowns can encapsulate methanol molecules by O—H...π interaction,which has been confirmed by X-ray crystal structures and ESI-MS.     

Preparation and Cytotoxicity of Novel Aliphatic Polycarbonate Synthesized from Dihydroxyacetone

A new cyclic carbonate, 2,2-ethylenedioxypropane-l,3-diol carbonate (EOPDC), was synthesized through a two-step reaction from dihydroxyacetone dimer, and polymerized in bulk initiated by Sn(Oct)2 to give a high molecular weight polycarbonate. The structure of monomer and the polymer were characterized by FT-1R, ^1H NMR, ^13C NMR. The cytotoxicity of the obtained polycarbonate was investigated by MTT assay.     

“LIVING”/CONTROLLED RADICAL POLYMERIZATION OF ETHYL METHYLACRYLATE WITH 2,2’-AZOBISISOBUTYRONITRILE/FERRIC CHLORIDE/TRIPHENYLPHOSPHINE INITIATION SYSTEM

"Living"/controlled radical polymerization of ethyl methacrylate (EMA) was carried out with a 2,2'-azobisisobutyronitrile (AIBN)/ferric chloride (FeCl_3)/triphenylphosphine (PPh_3) initiation system at 85℃. Thc numberaverage molecular weight (M_n) increases linearly with monomer conversion and the rate of polymerization is first order withrespect to monomer concentration. The M_w of PEMA ranges from 3900 to 17600 and the polydispersity indices are quitenarrow (1.09～1.22). The conversion can reach up to～100% and M_w of the polymers obtained is close to that designed. Thepolymerization mechanism belongs to the reverse atom transfer radical polymerization (ATRP). The polymer was end-functionalized by chlorine atom, which acts as a macroinitiator to proceed extension polymerization in the presence ofCuBr/bipy catalyst system via an ATRP process. The presence of ω-chlorine in the PEMA obtained was identified by ~1H-NMR spectrum.     

Poly(methyl methacrylate)/poly(N-isopropylacrylamide) core-shell particles prepared by seeded precipitation polymerization: Unusual morphology and thermo-sensitivity of zeta potential

Poly（methyl methacrylate）/poly（N-isopropylacrylamide） （PMMA/PNIPAM） core-shell particles were synthesized by seeded precipitation polymerization of N-isopropylacrylamide （NIPAM） in the presence of PMMA seed particles. The anionic potassium persulfate was used as initiator, and acrylic acid as functional comonomer. It was shown that the weight ratio of the PNIPAM shell to the PMMA core can be greatly increased through continuous addition of NIPAM monomer at a relatively slow rate. PMMA/PNIPAM particles with different shell thickness were obtained by varying the amount of charged NIPAM monomers. These particles exhibited unique nonspherical core-shell morphology. PMMA core was partially coated by dense hair-like or antler-like PNIPAM shell depending on the shell thickness. The measurement of these particles＇ zeta potential at different temperatures showed that the absolute value of zeta potential unusually decreased as the particle size decreased with temperature.     

SYNTHESIS AND FREE RADICAL POLYMERIZATION OF 2-OXO-3-METHYLEN E-5-PHENYL-1,4-DIOXAN

The novel cyclic monomer, 2-oxo-3-methylene-5-phenyl-1,4-dioxan, was synthesized by a set of reactions. Several intermediates were prepared and characterized in order to determine the monomer structure. The presence of chiral centers in the intermediates and resulting monomer makes it complicated to separate , purify and characterize them. It is a very reactive monomer which will polymerize even at room temperature if expose to moisture and air. This monomer can undergo essentially quantitative flee radical ring opening polymerization. The driving force for ring opening is the formation of new carbonyl group and benzylic radical. The monomer and polymer structure were established by IR, ~1H NMR, ~(13)C NMR and elemental analysis or high resolution mass spectrum. The molecular weight of the resulting polymer was estimated by viscosity determination.     

RING-OPENING POLYMERIZATION OF l,4-DIOXAN-2-ONE INITIATED BY LANTHANUM TRIS(2,6-DI-TERT-BUTYL-4-METHYLPHENOLATE)

The ring-opening polymerization of 1,4-dioxan-2-one (PDO) was carried out by lanthanum tris(2,6-di-tert-butyl-4-methylphenolate) (La(OAr)3) as novel single component initiator. The influences of polymerization reaction temperature and the molar ratio of monomer to initiator on the monomer conversion and molecular weight of poly(1,4-dioxan-2-one) (PPDO) were explored. PPDO with high viscosity average molecular weight of 1.95×105 can be prepared at 40℃when [PDO]/ [La(OAr)3] molar ratio was 800. Mechanism investigation shows that the polymerization proceeds through a "coordinationinsertion" mechanism with selective rupture of acyl-oxygen bond of PDO.     

采用柠檬酸合成高分散铜催化剂用于选择氢解反应

A highly dispersed Cu catalyst supported on silica was prepared by an incipient wetness impregnation method with citric acid.The synthesis was studied by nitrogen physisorption,X-ray diffraction,and temperature-programmed reduction by comparing with a reference prepared without citric acid.The catalyst precursor obtained after impregnation was X-ray amorphous.The precursor was readily transformed to crystalline CuO upon calcination.The CuO particles were of uniform size in a highly dispersed state and can be reduced to Cu at a lower temperature.The activity of the Cu catalyst obtained was an order of magnitude higher than that of the reference for the hydrogenolysis of methyl laurate to dodecanol.     

Synthesis and characterization of hyperbranched polyurethane-benzyltetrazole

A series of hyperbranched polyurethane-benzyltetrazoles（H-PBTZs） with different linkage structures were synthesized via the polycondensation of hexamethylenediisocyanate as an A₂ type monomer with（4-（1H-tetrazol-5- yl）benzyl）-diethanolamine（TBDEA） as a BB’₂ type monomer in the absence of catalyst at different temperatures.The FTIR, and ¹³C and ¹H-NMR spectroscopy were used to characterize the molecular structures of TBDEA and H-PBTZs as well as the counterpart linear polyurethane-benzyltetrazole（L-PBTZ）.The molecular composition was determined by the reaction selectivity that the isocyanate group reacted with the hydroxyl group in diethanolamine segment or the active hydrogen atom on tetrazole ring.Raising reaction temperature was propitious to the reaction of isocyanate group with the active hydrogen atom on tetrazole ring.The degrees of branching（DB） for H-PBTZs obtained from the ¹H-NMR spectra increased with raising reaction temperature.The wider molecular weight distribution of 1.7-2.9 for H-PBTZs was obtained via GPC analysis.TGA results showed that H-PBTZs had high thermal stability compared with L-PBTZ.     

"CAGE" VANADYL POLYCARBOXYLATE-THIOUREA COMPLEX FOR THE POLYMERIZATION OF ACRYLONITRILE

The polymerization of acrylonitrile (AN) in aqueous nitric acid initiated by " cage " vanadyl polycarboxylate (P=VO)-thiourea (TU) complex was investigated. The overall rate ofpolymerization isThe relationship between the induction period (τ) and the temperature of polymerization as well as the concentrations of reactants can be expressed as follows :The molecular weight of polyacrylonitrile increases with increasing monomer concentration and decreases with increasing temperature of polymerization and concentrations of vanadyl polycarboxylate and thioureaThe polymerization mechanism was proposed and discussed.     

Highly chemoselective lipase from Candida sp.99-125 catalyzed ring-opening polymerization for direct synthesis of thiol-terminated poly(e-caprolactone)

Lipase from Candida sp.99-125 catalyzed ring-opening polymerization of e-caprolactone in the presence of 6-mercapto-1-hexanol was presented as a new metal-free approach for direct synthesis of welldefined thiol-terminated poly(e-caprolactone).Remarkably,high chemoselectivity of lipase from Candida sp.99-125 toward hydroxyl and thiol was exhibited and quantitative thiol fidelity over 90% was achieved.The tedious protecting/deprotecting steps for thiol and metal residue were avoided.The polymerizations with around 70% monomer conversion were conducted in bulk and toluene at relative low temperature of 40 8C.Number–average molecular weight of resulted polymers ranged from 3000 to4700 Da by changing the feed ratio between monomer and initiator.The structures of obtained thiolterminated poly(e-caprolactone) were demonstrated by combining NMR and SEC analyses.     

Syntheses of 10-Hydroxy-5,10-dihydrophenophosphazine 10-Oxide and Its Methyl Derivatives

Ph2NH and PCl3 interacted at a molar ratio of 1:1.05 and slow-elevated temperature and then at 210-220 ℃ for 6h.The brown solution obtained was treated with H2O to produce a very hard brown solid believed to be a mixture of 5,10-dihydrophenophosphazine 10-oxide(1a) and 10,10′(5H,5H′）-spirobipenophosphazinium chloride(1b).This brown solid was directly oxidized with peracetic acid in HOAc prior to the separation of them to give compound 10-hydroxy-5,10-dihydropheno-phosphazine 10-oxide(2) with a higher yield(45%) than that of the literature(27%).When treated with excess SOCl2.compound 2 could quantitatively be converted to the corresponding phosphinyl chloride and the latter could further be transformed into 10-methoxy-5,10-dihydrophenophosphazine 10-oxide in 70% as treated with NaOMe in methanol.Compound 2 could also be converted to a bisanion when treated with NaH in DMF.The resulted bisanion reacted with MeI to give 5-methyl-10-hydroxy-5,10-dihydrophenophosphzine 10-oxide in a 73% yield which would be converted to 5-methyl-10-methoxy-5,10-dihydrophenophosphazine 10-oxide.All these compounds obtained were identified by surveying their melting points.and spectra and elemental analysis.     

Synthesis of Isotactic Polystyrene-block-Polyethylene by the Combination of Sequential Monomer Addition and Hydrogenation of 1,4-Trans-polybutadiene Block

Herein, we demonstrate the synthesis of a well-defined diblock copolymer consisting of isotactic polystyrene(iPS) and linear polyethylene, isotactic polystyrene-block-polyethylene(iPS-b-PE),by the combination ofsequential monomer addition and hydrogenation. Isospecific living polymerization of styrene and living trans-1,4-polymerization of 1,3-butadienewere catalyzed by 1,4-dithiabutandiyl-2,2′-bis(6-cumenyl-4-methylphenoxy) titanium dichloride(complex 1) activated by triisobutyl aluminum modified methylaluminoxane(MMAO) at room temperature to provide highly isotactic polystyrene(iPS) and 1,4-trans-polybutadiene(1,4-trans-PBD) with narrow molecular weight distribution. Furthermore, the iPS-b-1,4-trans-PBD was synthesized via sequential monomer addition in the presence ofcomplex 1 and MMAO.The hydrogenation of the 1,4-trans-PBD block was promoted by RuCl_2(PPh_3)_3 used as a catalyst to produce iPS-b-PE.     

Efficient dehydration of carbohydrates to 5-hydroxymethylfurfural in ionic liquids catalyzed by tin(Ⅳ) phosphonate and zirconium phosphonate

In this work,we synthesized tin(IV)phosphonate(SnBPMA)and zirconium phosphonate(ZrBPMA)by the reaction of SnCl4·5H2O or ZrOCl2·8H2O with N,N-bis(phosphonomethyl)aminoacetic acid,which was synthesized from a biomaterial glycine through a Mannich-type reaction.The SnBPMA and ZrBPMA were very efficient heterogeneous catalysts for the dehydration of fructose to produce 5-hydroxymethylfurfural(HMF),and the SnBPMA had higher activity than the ZrBPMA.The effects of solvents,temperature,reaction time,and reactant/solvent weight ratio on the reaction catalyzed by SnBPMA were investigated.It was demonstrated that the yield of HMF could reach 86.5%with 1-ethyl-3-methylimidazolium bromide([Emim]Br)as solvent,and the SnBPMA and SnBPMA/[Emim]Br catalytic system could be reused five times without considerable reduction in catalytic efficiency.Further study indicated that the SnBPMA and ZrBPMA in[Emim]Br were also effective for the dehydration of sucrose and inulin to produce HMF with satisfactory yields.     

Preparation and Characterization of Carbon Nanotubes-Coated Cordierite for Catalyst Supports

The carbon nanotubes-coated cordierite (CNTs-cordierite) was fabricated by pyrolysis of ethine on cordierite with iron catalyst, which was penetrated into the cordierite substrate by vacuum impregnation. The cordierite substrate, carbon naontubes, and CNTs-cordierite were characterized by SEM. TEM/HREM. BET, and TGA. The results show that the carbon nanotubes were distributed uniformly on the surface of cordierite. A significant increase in BET surface area and pore volume was observed, and a suitable pore-size distribution was obtained. On the CNTs-cordierite, carbon nanotubes penetrated into the cordierite substrate, which led to a remarkable stability of the CNTs against ultrasound maltreatment. Growth time is an important factor for thermostability and texture of the sample. The mass increased but the purity decreased with the growth time, which caused the exothermic peak shift to low temperature, and the corresponding full width half maximum (FWHM) of the peak in DTG increased.     

Thermally Stable and Organo-soluble Polyamides Containing Triazine Rings and Ether Linkages in the Main Chain: Synthesis and Characterization

In order to synthesize new polyamide(PA) 5 and copolyamides(Co PA) 7a-7d, a new-type of dicarboxylic acid containing triazine ring was successfully synthesized from 2,4-dichloro-6-methoxy-s-triazine 1 and 4-aminobenzoic acid. New polyamide 5 containing triazine moiety was prepared from 4,4'-(6-methoxy-1,3,5-triazine-2,4-diyl)bis(azanediyl)dibenzoic acid 3 and 4,4′-diaminodiphenylether by direct polycondensation reaction. Then new series thermally stable copolyamides 7a-7d with high solubility in common organic solvents were synthesized from the direct polycondensation reaction of diacid 3 as a first monomer, aliphatic-aromatic diacids 6a-6d as second diacids and 4,4′-diaminodiphenylether. All of the above polymers were fully characterized by 1H-NMR and FTIR spectroscopy, elemental analysis(CHN), inherent viscosity, solubility tests, gel permeation chromatography(GPC), differential scanning calorimetry(DSC) and thermogravimetric analysis(TGA). The resulted Co PAs 7a-7d have shown good inherent viscosities, solubility and thermal properties.