ORGANO-SOLUBLE FLUORINATED POLYIMIDES DERIVED FROM a,a-BIS(4-AMINO-3,5- DIMETHYLPHENYL)-4′-FLUOROPHENYL METHANE AND VARIOUS AROMATIC DIANHYDRIDES

 Organo-soluble fluorinated polyimides were synthesized by the polycondensation of a new aromatic diamine -bis(4-amino-3,5-dimethylphenyl)-4′-fluorophenyl methane with several aromatic dianhydrides. The one-step polymerization procedure was conducted at 180℃ in m-cresol, producing the polyimides with inherent viscosities of 0.680.76 dL•g1. The polyimides could be soluble not only in polar aprotic solvents, such as N-methyl-2-pyrrolidinone, and N,N-dimethylacetamide, but also in common organic solvents, such as chloroform, cyclopentanone, m-cresol and so on. The polyimide films show excellent transparency with the UV-Vis cut-off lengths of 310360 nm and light transmittances of higher than 80% in the visible region. In addition, the polyimides exhibit good thermal stability with an initial decomposition temperature (Td) higher than 530℃ and have more than 60% of residual weight retentions at 700℃.     

ORGANO-SOLUBLE FLUORINATED POLYIMIDES DERIVED FROM α,α-BIS(4-AMINO-3,5-DIMETHYLPHENYL)-4''''-FLUOROPHENYL METHANE AND VARIOUS AROMATIC DIANHYDRIDES

Organo-soluble fluorinated polyimides were synthesized by the polycondensation of a new aromatic diamine α,α-bis(4-amino-3,5-dimethylphenyl)-4'-fluorophenyl methane with several aromatic dianhydrides.The one-step polymerizationprocedure was conducted at 180℃in m-cresol,producing the polyimides with inherent viscosities of 0.68-0.76 dL.g~(-1).Thepolyimides could be soluble not only in polar aprotic solvents,such as N-methyl-2-pyrrolidinone,and N,N-dimethylacetamide,but also in common organic solvents,such as chloroform,cyclopentanone,m-cresol and so on.Thepolyimide films show excellent transparency with the UV-Vis cut-off lengths of 310-360 nm and light transmittances ofhigher than 80% in the visible region.In addition,the polyimides exhibit good thermal stability with an initial decompositiontemperature(T_d)higher than 530℃and have more than 60% of residual weight retentions at 700℃.     

A Novel Diamine, 4＇-Phenyiphenyi 4-（3＂, 5＂-Diaminobenzoyioxy）- benzoate and Longer Side-chain Polyimide

This is a part of our systematic research work on polyimides with mesogenic unit side chain. In this study, a new 4＇-phenylpbenyl 4-（3＂,5＂-diaminobenzoyloxy）benzoate and polyimide were synthesized, and characterized by FTIR, ^1H-NMR, inherent viscosity, mechanical properties, and solubility measurements. The diamine composed with mesogenic unit aryl ester groups and bipbenyl group with longer L/D ratio, was synthesized by two key steps. Firstly, the hydroxy group of 4-hydroxybenzoic acid was protected by acetoxy group for avoiding self- polymerization of 4-hydroxybenzoic acid, and then selectively hydrolyzed after esterification of carboxyl. Secondly, a selective catalysis hydrogenation was adopted to prevent the aryl ester from deoxidation. Based on this diamine, a novel polyimide was prepared by polycondensation of 4＇-phenylphenyl 4-（3＂, 5＂-diaminobenzoyloxy）benzoate and 4-aminophenyl ether（ODA） with 4, 4＇-oxydiphthalic anhydride（ODPA） in N-methyl-2-pyrrolidone （NMP）. The resulting polyimide with longer side chain showed better solubility and more regular structure. Its inherent viscosity is lower than that without side chains, but its modulus and strength not only maintained, even improved.     

Synthesis of a Novel Diamine 4-[(4''''-Butoxyphenoxy)carbonyl]phenyl-3",5"-diaminobenzoate and Corresponding Polyimides

A novel diamine 4-[(4'-butoxyphenoxy)carbonyl]phenyl-3",5"-diaminobenzoate (BCDA) was synthesized from 4-butoxyphenol, 4-hydroxybenzoic acid and 3,5-dinitrobenzoic acid through four main intermediates, and a series of polyimides were also synthesized. All the intermediates and the final product were characterized by FTIR and 1H-NMR. The key step in synthesis route is selective hydrolyzation of two ester groups in 4-butoxyphenyl-4'-acetoxybenzoate, by adjusting the reaction temperature and the concentration of ammonia, shorteding the reaction time. The properties of the novel polyimides, such as the aggregation structures, glass transition temperature, solubility and the pretilt angles, were carried out.     

Synthesis of a Novel Diamine 4-[（4＇-Butoxyphenoxy）carbonyl]- phenyl-3＂, 5＂-diaminobenzoate and Corresponding Polyimides

A novel diamine 4-[（4＇-butoxyphenoxy）carbonyl]phenyl-3＂,5＂-diaminobenzoate （BCDA） was synthesized from 4-butoxyphenol, 4-hydroxybenzoic acid and 3,5-dinitrobenzoic acid through four main intermediates, and a series of polyimides were also synthesized. All the intermediates and the final product were characterized by FTIR and 1H-NMR. The key step in synthesis route is selective hydrolyzation of two ester groups in 4-butoxyphenyl-4＇-acetoxybenzoate, by adjusting the reaction temperature and the concentration of ammonia, shorteding the reaction time. The properties of the novel polyimides, such as the aggregation structures, glass transition temperature, solubility and the pretilt angles, were carded out.     

Low-bandgap polymers with quinoid unit as π bridge for high-performance solar cells

To construct efficient low band gap polymers, increasing the Quinone structure of the polymer backbone could be one desirable strategy. In this work, two D–Q–A–Q polymers P1 and P2 were designed and synthesized with thiophenopyrrole diketone(TPD) and benzothiadiazole(BT) unit as the core and ester linked thieno[3,4-b]thiophene(TT) segment as π-bridging, and the main focus is to make a comparative analysis of different cores in the influence of the optical, electrochemical, photochemical and morphological properties. Compared with the reported PBDTT_(EH–)TBTT_(HD-i), P1 exhibited the decreased HOMO energy level of-5.38 e V and lower bandgap of 1.48 e V. Furthermore, when replaced with BT core, P2 showed a red-shifted absorption profile of polymer but with up-shifted HOMO energy level. When fabricated the photovoltaic devices in conventional structure, just as expected, the introduction of ester substituent made an obvious increase of V_(OC) from 0.63 to 0.74 V for P1. Besides, due to the deep HOMO energy level,higher hole mobility and excellent phase separation with PC_(71) BM, a superior photovoltaic performance(PCE = 7.13%) was obtained with a short-circuit current density(J_(SC)) of 14.9 m A/cm~2, significantly higher than that of P2(PCE = 2.23%). Generally, this study highlights that the strategy of inserting quinoid moieties into D–A polymers could be optional in LBG-polymers design and presents the importance and comparison of potentially competent core groups.     

A Novel Diamine, 4′-Phenylphenyl 4-(3″, 5″-Diaminobenzoyloxy)- benzoate and Longer Side-chain Polyimide

This is a part of our systematic research work on polyimides with mesogenic unit side chain. In this study, a new 4′-phenylphenyl 4-(3″,5″-diaminobenzoyloxy)benzoate and polyimide were synthesized, and characterized by FTIR, 1H-NMR, inherent viscosity, mechanical properties,and solubility measurements. The diamine composed with mesogenic unit aryl ester groups and biphenyl group with longer L/D ratio, was synthesized by two key steps. Firstly, the hydroxy group of 4-hydroxybenzoic acid was protected by acetoxy group for avoiding self- polymerization of 4-hydroxybenzoic acid, and then selectively hydrolyzed after esterification of carboxyl.Secondly, a selective catalysis hydrogenation was adopted to prevent the aryl ester from deoxidation. Based on this diamine, a novel polyimide was prepared by polycondensation of 4′-phenylphenyl 4-(3″, 5″-diaminobenzoyloxy)benzoate and 4-aminophenyl ether(ODA) with 4,4′-oxydiphthalic anhydride(ODPA) in N-methyl-2-pyrrolidone (NMP). The resulting polyimide with longer side chain showed better solubility and more regular structure. Its inherent viscosity is lower than that without side chains, but its modulus and strength not only maintained, even improved.     

Side-chain engineering of high-efficiency conjugated polymer photovoltaic materials

In recent years,conjugated polymers have attracted great attention in the application as photovoltaic donor materials in polymer solar cells(PSCs).Broad absorption,lower-energy bandgap,higher hole mobility,relatively lower HOMO energy levels,and higher solubility are important for the conjugated polymer donor materials to achieve high photovoltaic performance.Side-chain engineering plays a very important role in optimizing the physicochemical properties of the conjugated polymers.In this article,we review recent progress on the side-chain engineering of conjugated polymer donor materials,including the optimization of flexible side-chains for balancing solubility and intermolecular packing(aggregation),electron-withdrawing substituents for lowering HOMO energy levels,and two-dimension(2D)-conjugated polymers with conjugated side-chains for broadening absorption and enhancing hole mobility.After the molecular structural optimization by side-chain engineering,the2D-conjugated polymers based on benzodithiophene units demonstrated the best photovoltaic performance,with powerconversion efficiency higher than 9%.     

Solvent-free esterification of poly（vinyl alcohol） and maleic anhydride through mechanochemical reaction

A solid-state mechanochemical processing,that is,pan-milling,was used to conduct the esterification of poly(vinyl alcohol) (PVA) with maleic anhydride (MA) through stress-induced reaction.FTIR spectrum study indicated the presence of ester linkages and olefinic double bonds in maleic anhydride cross-linked PVA.Thermal properties of the cross-linked product were characterized by DSC.The results showed its glass transition temperature was 20℃higher than the original linear PVA and the thermal stability was also improved.     

Conformational Properties of Comb-shaped Polyelectrolytes with Negatively Charged Backbone and Neutral Side Chains Studied by a Generic Coarse-grained Bead-and-Spring Model

A generic coarse-grained bead-and-spring model,mapped onto comb-shaped polycarboxylate-based(PCE)superplasticizers,is developed and studied by Langevin molecular dynamics simulations with implicit solvent and explicit counterions.The agreement on the radius of gyration of the PCEs with experiments shows that our model can be useful in studying the equilibrium sizes of PCEs in solution.The effects of ionic strength,side-chain number,and side-chain length on the conformational behavior of PCEs in solution are explored.Single-chain equilibrium properties,including the radius of gyration,end-to-end distance and persistenee length of the polymer backbone,shape-asphericity parameter,and the mean span dimension,are determined.It is found that with the increase of ionic strength,the equilibrium sizes of the polymers decrease only slightly,and a linear dependenew of the persistence length of backbone on the Debye screening length is found,in good agreement with the theory developed by Dobrynin.Increasing side-chain numbers and/or side-chain lengths increases not only the equilibrium sizes(radius of gyration and mean span)of the polymer as a whole,but also the persistence length of the backbone due to excluded volume interactions.     

Efficient side-chain modification of dextran via base-catalyzed epoxide ring-opening and thiol-ene click chemistry in aqueous media

In this study, a novel approach by combining base-catalyzed epoxide ring-opening and thiol-ene click chemistry is presented for the side-chain modification of dextran. The vinyl-modified dextran is prepared by a basic epoxide ring opening reaction of allyl glycidyl ether in 0.1 mol/L NaOH, followed by thiol-addition click reaction of three model sulfhydryl compounds using water-soluble Irgacure 2959 as the photoinitiator, leading to side-chain functionalized dextran modified with carboxyl, bidentate dicarboxyl or amino groups. This is the first example of combining epoxide ring-opening and thiol- ene click chemistry for side-chain modification of dextran in aqueous media. Importantly, it may also be extended as a convenient and efficient method for the side-chain modification of other polysaccharides.     

Synthesis of Fragment Derivatives of Delta Sleep-inducing Peptide （1-4） Catalyzed by Enzymes in Organic Solvents

Synthesis of two fragment derivatives of delta sleep-inducing peptide (DSIP) (1-4), Boc-Trp-Ala-Gly-GlyNHNHPh (1) and Boc-Trp-Ala-Gly-GlyOEt (2), catalyzed by proteases via 2 2 or 1 3 synthetic routes with different protecting groups at C-terminal in organic solvents was reported. The yield of N-Boc tetrapeptide with phenylhydrazinyl protecting carboxyl group at C-terminal (1) was higher than that of N-Boc tetrapeptide ethyl ester (2) by 2 2 route. The factors influencing the synthetic yield of the fragments of DSIP (1-4) were discussed.     

Structural and electronic properties of single-walled carbon nanotubes adsorbed with 1-pyrenebutanoic acid, succinimidyl ester

The adsorption of a 1-pyrenebutanoic acid, succinimidyl ester (PSE) interacting with metallic armchair (n, n) carbon nanotubes (CNTs) (n= 3-13) was investigated by using a density-functional tight-binding method with an empirical van der Waals force correction. In this study of large systems involving weak interactions, our calculations showed that the pyrene ring of PSE could be spontaneously absorbed onto the CNTs surface through π-π stacking at the physisorption distances. Increasing of the CNTs diameter leads to a higher adsorption energy. After adsorption of PSE on its sidewall, the geometric and electronic structures of CNTs are basically undamaged. CNTs contribute to the main peak of the electron excitation procedure in the UV/vis spectrum, with a slight red shift after adsorption of PSE.     

Identification of in vitro and in vivo metabolites of 12β-hydroxylveratroylzygadenine associated with neurotoxicity by using HPLC–MS/MS

Metabolism study was carried out on 12b-hydroxylveratroylzygadenine(VOG) that is a cevine-type alkaloid existing in Veratrum nigrum L. and a neurotoxic component. In order to better understand the potential mechanism of neurotoxicity of VOG, this study measured VOG-induced DNA damage in the cerebellum and cerebral cortex of mice after 7 days repetitive oral dose by using single-cell gel electrophoresis(Comet assay). High performance liquid chromatography-tandem mass spectrometry(LC–MS/MS) was developed and applied to separate and identify in vitro and in vivo metabolites of VOG for investing the possible relationship of metabolism and neurotoxicity. In vitro experiment was carried out using rat liver microsomes, while the in vivo study was conducted on rats. The obtained results indicated that VOG might cause DNA damage in cerebellum and cerebral cortex of mice in a dosedependent manner. Hydrolysis of ester bond and O-demethylation were proposed to be the main in vivo metabolic pathways of VOG, while the major in vitro metabolic pathways were proposed as methyl oxidation to aldehyde, dehydrogenation, hydrolysis of ester bond, hydrolysis of ester bond together with acetylation, and methoxylation. O-Demethylation reaction was likely to be associated with reactive oxygen species production, leading to the DNA damage.     

Synthesis,Spectroscopic Properties,and Photodynamic Anticancer Activities of Novel Arginine-modified Silicon(Ⅳ) Phthalocyanines

We design and synthesize a series of novel silicon(IV)phthalocyanines(SiPcs,1a,2a,1b,and 2b)axially conjugated with arginine or arginine-containing oligopeptides(Arg-Arg,Cys-Arg,Cys-Arg-Arg)through ester or ether linkers to demonstrate the effects of substituents and coupling ways on the spectral behaviors and photodynamic activities.The ester-linked SiPcs(1a and 2a)show slight red-shift,higher fluorescence emission and singlet oxygen generation compared to the ether-linked analogues(1b and 2b)due to the stronger electron-withdrawing ability of the ester group,suggesting that electronic effect of the linkers plays an important role in their spectral properties.The introduction of arginine could effectively reduce the aggregation of phthalocyanine in aqueous solutions.With higher cellular uptake and plasma membrane localization ability,1b and 2b exhibit significantly higher photocytotoxicity against both HepG2 and Hela cells.Moreover,the in vivo fluorescence imaging suggests that 2b is the most specific toward H22 tumor-bearing ICR mice,and it shows efficient tumor growth inhibition with the tumor inhibition rate up to 93%.Thus,this work would provide a new reference for the development of phthalocyanine-based photosensitizers.     

Soluble polyimides from a semi-aliphatic diamine containing ester,amide and ether groups

A diamine was synthesized by two successive reactions.Nucleophilic reaction of 4-hydroxybenzoic acid with terephthaloyl chloride yielded terephthaloyl bis(4-oxybenzoic) acid.Then reaction of this compound with 1,8-diamino-3,6- dioxaoctane via Yamazaki method resulted in preparation of diamine named terephthalic acid bis(4-{2-[2-(2-amino ethoxy)ethoxy]ethyl carbamoyl}phenyl) ester.After fully characterization it was used to prepare new polyimides through polycondensation with different dianhydrides using trimethylchlorosilane.Characterization of polymers was achieved by common methods and their physical properties including inherent viscosity,thermal behavior,thermal stability,crystallinity and solubility were studied.Prepared polyimides showed improved solubility and good thermal stability.     

Biodiesel preparation from transesterification of glycerol trioleate catalyzed by basic ionic liquids

In the present study,the transesterification of glycerol trioleate was carried out over a basic ionic liquid,1-butyl-3- methylimidazolium hydroxide([Bmim]OH) and an 87.2%yield of methyl ester was achieved.The product was isolated through simple decantation from the biphasic system due to the immiscibility of[BmimJOH with ester.[Bmim]OH can be easily recovered and reused six times without dramatic decrease in ester yield.     

Activity and basic properties of KOH/mordenite for transesterification of palm oil

The catalytic performance of KOH/mordenite has been studied for transesterification of palm oil using a batch reactor and a packed-bed reactor at 60 C and atmospheric pressure.The KOH/mordenite processed transesterification in the batch reactor gave the highest methyl ester yield of96.7%under optimum conditions,while a methyl ester content over 94.5%was obtained in the packed-bed reactor.This comparison indicates that transesterification in a batch-type reactor gives a higher methyl ester yield than that of a continuous-flow reactor.Dealumination was found in the calcined catalysts and had a significant effect on the physical structure and chemical composition of the catalysts.Leaching of the potassium species was negligible,whereas depositing and washing of the reacted mixture with acetone on the catalyst surface were observed by FTIR.     

二[1-(2-噻吩基)-4,4,4-三氟丁二酮-1,3]合铜(Ⅱ)及其某些溶剂加合物的热分析研究

Thermoanalysis study has been carried out on the complex of bis[1-(2-thienyl)-4,4,4-trifluoro-butanedione- 1,3]copper(Ⅱ) and its adducts with pyridine, 2,2′-bipyridine, quinoline and dimethyl sulfoxide in a dynamic ni-trogen atmosphere by simultaneous TG-DTG-DSC technique. The experimental results showed that the decomposi-tion modes of the solvent molecules were various according to the different structures of the complex, in general, the decomposition of them was ahead of the decomposition of the ligand 1-(2-thienyl)-4,4,4-triflurobu- tanedione-1,3. Among them the adduct with 2,2-bipyridine showed a quite unique thermal behavior. Several methods have been jointly used to study the kinetics of all the thermal decomposition stages for title compounds, which showed that the evolution of the solvent molecules was controlled mainly by Rn mechanism (or Am mechanism for 2,2-bipyridine adduct) with lower activation energy; while the release of 1-(2-thienyl)-4,4,4-trifluro-butane- dione-1,3 was gove- rned by D2 or D3 mode with higher activation energy.     

TRANSESTERIFICATION OF POLY（BISPHENOL A CARBONATE） WITH AROMATIC AND ALIPHATIC SEGMENTS IN BUTYLENE TEREPHTHALATE-CAPROLACTONE COPOLYESTER

In this article, the transesterification of poly(bisphenol A carbonate) (PC) with butylene terephthalate-caprolactone copolyester at a weight ratio 50/50 (BCL(21)) was thoroughly investigated by proton nuclear magnetic resonance spectroscopy (^1H-NMR), in conjunction with a model compound. The ^1H-NMR results of the annealed blend PC/BCL(21) show that the formation of bisphenol A-terephthalate ester units is the same as in the annealed blend of PC with PBT, and the transesterification actually occurs between PC and butylene terephthalate (BT) segments in BCL(21). By comparison with the model compound bisphenol A dibutyrate, the new signal appearing at δ=2.56 in the ^1H-NMR spectrum confirms the existence of bisphenol A caprolactone ester units resulting from the exchange reaction of PC with caprolactone (CL) segments. ^1H-NMR analysis of the transesterification rates reveals that the reaction of PC with aromatic and aliphatic segments in BCL(21) proceeds in a random manner. The miscibility of the blend PC/BCL(21) copolyester is favorable for the transesterification of PC with BT segments and CL segments.