Fabrication of Poly（4-vinylpyridine） Nanofiber and Fluorescent Poly（4-vinylpyridine）/Porphyrin Nanofiber by Electrospinning

Poly（4-vinylpyridine）（P4-VP） nanofiber and fluoresent poly（4-vinylpyridine）/porphyrin（P4-VP/TPPA） nanofiber were respectively prepared by electrospinning. The effect of the concentration of P4-VP/dimethylformamide （DMF） electrospinning solutions on the morphology of P4-VP nanofiber was investigated and it was found that the average diameter of the nanofiber of P4-VP/DMF increased with the increase of the concentration of the spinning solution. After the addition of TPPA to the P4-VP/DMF spinning solution, the diameter of P4-VP/TPPA nanofiber became even due to the increase of the conductivity of the P4-VP/DMF-TPPA solution. The photoluminescent（PL） spectral analysis indicates that the emission peak position of P4-VP/TPPA nanofiber is almost the same as that of pure TPPA at about 650 nm without peak shift, and when it was stored for 20 days, the emission peak of P4-VP/TPPA nanofiber is also at 650 nm, indicating that the fluorescent property of P4-VP/TPPA nanofiber is stable. Fourier-transform iufrared（FTIR） spectrum confirms the chemical composition of the resulting P4-VP/TPPA composite nanofiber.     

STABILITY OF POLY（N,N＇-METHYLENEBISACRYLAMIDE-co-4-VINYLPYRIDINE） MICROGEL DISPERSION AND ADJUSTMENT OF THE HYDROPHOBICITY IN THE MICROGELS

In the UV-Vis spectra of pure light-scattering systems, there is an exponential relationship between absorbance and wavelength （A = Kλ^-n）. Here, the exponent n is named as flocculation-coagulation parameter. In the present paper, the effects of different additives on the stability of poly（N,N＇-methylenebisacrylamide-co-4-vinylpyridine） （poly（Bis-co-4-VP）） microgel dispersion were studied in detail via this parameter. The results showed that the stability of the dispersion mainly comes from the ionization of pyridine groups, making the microgel positively charged on its surface. This was confirmed by the measurement of Zeta potential and the result of conductometric titration. The result of fluorescence analysis indicated that the hydrophobicity in the microgels is enhanced with the increase in total 4-VP unit content.     

A novel and selective oxidation of benzylic alcohols with polymer-supported periodic acid under mild aprotic conditions

A new polymeric oxidizing reagent was prepared by supporting periodic acid on poly（1,4-phenylene-2,5-pyridine dicarboxyamide）. This polymeric reagent was used for the selective oxidation of primary benzylic alcohols to the corresponding benzaldehydes in CH₃CN at reflux conditions.Excellent selectivity was observed between primary benzyl alcohols and secondary ones as well as non-benzylic alcohols in the oxidation reactions.Allylic alcohols were also converted to the corresponding aldehydes with good yields.     

EFFECTS OF L-PHENYLALANINE ON THE RADIATION SYNTHESIS OF POLY （N,N＇-METHYLENEBIS A CR YLAMIDE-co-4-VINYLPYRID INE） （MICRO）GELS

The effects of L-phenylalanine （L-Phe） on the synthesis ofpoly（N,N＇-methylenebisacrylamide-co-4-vinylpyridine） （poly（Bis-co-4-VP）） （micro）gels by γ-ray irradiation were studied. The addition of L-Phe could not only decrease the gelation dose （Dg） of the synthesis obviously, but also transform the morphology of copolymer from microgel to gel. In addition, the swelling ability of the （micro）gels was also affected in the presence of L-Phe. The decrease of Dg was ascribed to the effect of pH, while the transformation of the morphology was ascribed to the effect of L-Phe on the stability of the poly（Bis-co-4-VP） microgel. Such an effect was confirmed further as compared with the effects of L-alanine, L-glutamic acid, L-arginine, sulfuric acid and aqueous ammonia.     

STABILITY OF POLY(N,N''''-METHYLENEBISACRYLAMIDE-co-4-VINYLPYRIDINE)MICROGEL DISPERSION AND ADJUSTMENT OF THE HYDROPHOBICITY IN THE MICROGELS

In the UV-Vis spectra of pure light-scattering systems,there is an exponential relationship between absorbance and wavelength(A=Kλ~(-n)).Here,the exponent n is named as flocculation-coagulation parameter.In the present paper,the effects of different additives on the stability of poly(N,N'-methylenebisacrylamide-co-4-vinylpyridine)(poly(Bis-co-4-VP)) microgel dispersion were studied in detail via this parameter.The results showed that the stability of the dispersion mainly comes from the ionization of pyridine groups,making the microgel positively charged on its surface.This was confirmed by the measurement of Zeta potential and the result of conductometric titration.The result of fluorescence analysis indicated that the hydrophobicity in the microgels is enhanced with the increase in total 4-VP unit content.     

EFFECTS OF L-PHENYLALANINE ON THE RADIATION SYNTHESIS OF POLY(N,N''''-METHYLENEBISACRYLAMIDE-co-4-VINYLPYRIDINE)(MICRO)GELS

The effects of L-phenylalanine(L-Phe)on the synthesis of poly(N,N'-methylenebisacrylamide-co-4-vinylpyridine) (poly(Bis-co-4-VP))(micro)gels by γ-ray irradiation were studied.The addition of L-Phe could not only decrease the gelation dose(D_g)of the synthesis obviously,but also transform the morphology of copolymer from microgel to gel.In addition,the swelling ability of the(micro)gels was also affected in the presence of L-Phe.The decrease of D_g was ascribed to the effect of pH,while the transformation of the morphology was ascribed to the effect of L-Phe on the stability of the poly(Bis-co-4-VP)microgel.Such an effect was confirmed further as compared with the effects of L-alanine,L-glutamic acid,L-arginine,sulfuric acid and aqueous ammonia.     

Synthesis and Characterization of Amphiphific Block Copolymer Containing PVP and Poly（5-benzyloxytrimethylene carbonate）

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.     

PREPARATION OF POLYMER MICROSPHERES WITH PYRIDYL GROUP AND THEIR STABILIZED GOLD METALLIC COLLOIDS

Narrow disperse poly(ethyleneglycol dimethacrylate-co-4-vinylpyridine)(poly(EGDMA-co-4-VPy))microspheres were prepared by distillation-precipitation copolymerization of ethyleneglycol dimethacrylate(EGDMA)and 4-vinylpyridine (4-VPy)with 2,2'-azobisisobutyronitrile(AIBN)as initiator in neat acetonitrile.The polymer microspheres containing pyridyl group were then utilized as stabilizer for gold metallic colloids with the diameter around 7 nm,which were prepared by the in situ reduction of gold chloride trihydrate with sodium borohydride through the coordination of the pyridyl group on the gel layer and surface of the microsphere with the gold metallic nano-particles.The catalytic properties of the pyridyl- functionalized microsphere-stabilized gold metallic colloids and the behavior of the stabilized-catalyst for the recycling were investigated with reduction of 4-nitrophenol to 4-aminophenol as a model reaction.     

Poly（acrylonitrile-co-3-aminocarbonyl-3-butenoic acid methyl ester）： A better precursor material for carbon fiber than acrylonitrile terpolymer

In order to improve the stabilization and spinnability of polyacrylonitrile, a bifunctional comonomer containing both ester and amide groups was synthesized to prepare poly（acrylonitrile-co-3- aminocarbonyl-3-butenoic acid methyl ester） [P（AN-co-ABM）] copolymers used as the carbon fiber precursor instead of poly（acrylonitrile-acrylamide-methyl acrylate） [P（AN-AM-MA）] terpolymer. The differential scanning calorimetry and thermogravimetry results show that the stabilization of P（AN-co- ABM） have been remarkably improved by ABM compared with P（AN-AM-MA） terpolymer, such as lower initiation temperature, broadened exothermic peak and smaller activation energy. Moreover, the spinnability of P（AN-co-ABM） is also improved by ABM due to the lubrication of ester groups in ABM. This study clearly shows that P（AN-co-ABM） copolymer is a better material for use as a carbon fiber precursor than P（AN-AM-MA） terpolymer.     

SYNTHESIS OF POLYMERIC β-CYCLODEXTRIN SUPPORTED BY CROSSLINKED POLY(ACRYLAMIDE-co-VINYLAMINE)AND ITS CATALYSIS OF THE HYDROLYSIS OF p-NITROPHENYL ACETATE

Polymeric β-cyclodextrin (β-CD) supported by crosslinked poly(acrylamide-co-vinylamine) was synthesized as anartificial analog of hydrolytic enzyme and its catalysis of the hydrolysis of p-nitrophenyl acetate (p-NPA) was theninvestigated. The result showed that the polymer-supported β-CD could accelerate the hydrolytic reaction of p-NPA morequickly than β-CD itself and crosslinked poly(acrylamide-co-vinylamine) alone. The acceleration rate of the polymer-supported β-CD was about 10 times as fast as that of free β-CD in 0.01 mol/L phosphate buffer (pH 7.4) containing 32%DMSO at 37±0.1℃ when the molar amount of β-CD units in the polymer was equal to that of free β-CD in the experiments.The enhanced acceleration of thc polymer-supported β-CD should be ascribed to the cooperative contribution of theinclusion effect of β-CD ring and the nucleophilic effect of amino groups on the polymeric support.     

Cross-linked poly (4-vinylpyridine) supported azide ion as a versatile and recyclable polymeric reagent for synthesis of 1-substituted-1H-1,2,3,4-tetrazoles

Cross-linked poly (4-vinylpyridine) supported azide ion, [P₄-VP]N₃, is easily prepared and used as an efficient polymeric reagent for synthesis of 1-substituted-1H-1,2,3,4-tetrazoles via condensation reaction of azide ion, primary aromatic amines, and triethyl orthoformate in glacial acetic acid. After optimization of the reaction conditions, a wide variety of primary aromatic amines were also subjected to preparation of the corresponding 1-aryl-1 H-1,2,3,4- tetrazoles using [P₄-VP]N₃ under heterogeneous conditions. In this method, the reaction times were very short and the isolated yields were excellent (90–98 %). 1-Aryl-1H-1,2,3,4- tetrazole products were characterized by Fourier transform infrared (FT-IR) and some of them were also characterized by proton nuclear magnetic resonance (¹H NMR) spectroscopy, and physical properties were compared with the literature values of known compounds. The spent polymeric reagent were regenerated quantitatively and reused for several cycles without significant loss of their activity.     

Synthesis of polymer-supported Fe3O4 nanoparticles and their application as a novel route for the synthesis of imidazole derivatives

Research on Chemical Intermediates - Cross-linked poly(4-vinylpyridine) supported Fe3O4 nanoparticles, abbreviated as [P4-VP]-Fe3O4NPs, were easily prepared as a new magnetic polymeric catalyst and...     

A mild, clean, and simple synthesis of symmetrical carboxylic anhydrides from carboxylic acides using a polymer supported tosyl chloride

The use of polymeric reagents simplifies routine acylation of carboxylic acid because it eliminates the traditional purification. We describe the use of readily available cross-linked poly(4-vinylpyridine) supported tosyl chloride, [P₄VP].TsCl, in the suspended solution phase synthesis of symmetrical anhydrides from carboxylic acids in the presence of K₂CO₃ in high yields and purity. The products can be obtained by filtration and evaporation of the solvent.     

Rapid and facile synthesis of acyl azides from acyl halides using a polymer-supported azide ion under heterogeneous conditions

In this article a rapid and facile method for synthesis of acyl azide is described. The cross-linked poly(N-methyl-4-vinylpyridinium) azide ion, [P₄-VP]N₃ is prepared and used as an efficient polymeric reagent for synthesis of acyl azides from acyl halides at room temperature under heterogeneous conditions. Various benzoyl halides, with electron-withdrawing groups as well as electron-donating groups, were transformed into the corresponding benzoyl azides in high to excellent yields in short reaction times. The acyl azide products were characterized by FT-IR, and some of them were also characterized by ¹H-and/or ¹³C-NMR spectroscopy, and physical properties were compared to literature values of known compounds. The spent polymeric reagents can be regenerated and reused for several times without losing their activity. Relative to the reported methods, the present method has the advantages of operational simplicity, mild reaction conditions, fast reaction rates, simple reaction work-up and lower hazardous and potentially explosive nature. Also the present method is the first procedure for the synthesis of acyl azides from acyl halides by using a polymer-supported azide ion under heterogeneous conditions.     

Polymer‐Supported Thiocyanate as New,Versatile and Efficient Polymeric Reagent for Conversion of Alkyl Halides to Corresponding Alkyl Thiocyanates under Mild Conditions

Crosslinked poly(N‐methyl‐4‐vinylpyridinium)thiocyanate [P₄‐Me]SCN (II) is prepared easily and is used as a new polymeric reagent for synthesis of alkyl thiocyanates from alkyl halides under mild and nonaqueous conditions. The used polymeric reagent usually can be removing quantitatively and be regenerated.     

Functionalization of crosslinked poly(4-vinylpyridine) and poly(4-vinylpyridine-co-styrene) with permanganate species: Preparation of poly(4-vinylpyridinium permanganate)s and their use as oxidizing reagents

Crosslinked poly(4-vinylpyridine) and poly(4-vinylpyridine-co-styrene) were functionalized with permanganate group to afford the corresponding poly[4-vinyl(pyridinium permanganate)] resin. These resins were found to selectively oxidize alcohols to corresponding carbonyl compounds. These insoluble functionalized polymers possess the desired characteristics of the polymeric reagents, including operational simplicity, filterability, and regenerability. The influence of solvent, duration of reaction, and molar excess of the reagent in these oxidation reactions was investigated to find out the optimum conditions for effective oxidation reactions. The reactions were found to be more facilitated in nonpolar solvents, and a large excess of the polymeric reagent did not have any significant effect on the extent of reactions. The poly[4-vinyl(pyridinium permanganate)] resin bears a contrast to KMnO₄ and other polymer-supported oxidizing agents like poly[4-vinyl(pyridinium chlorochromate)] in that it does not bring about the oxidation of the alcohol group directly attached to the ring structure.     

One-pot three-component synthesis of 1,4-disubstituted 1H-1,2,3-triazoles using green and recyclable cross-linked poly(4-vinylpyridine)-supported copper sulfate/sodium ascorbate in water/t-BuOH system

Cross-linked poly(4-vinylpyridine)-supported copper sulfate, [P₄-VP]CuSO4 as a green and recyclable, heterogeneous catalyst in the presence of sodium ascorbate (NaAsc), is reported for the regioselective synthesis of 1,4-disubstituted-1,2,3-triazoles from benzyl halides, sodium azide and terminal alkyne in water/t-BuOH (1/1:V/V) at 70 °C. Various alkyl halides and benzyl halides, with electron-withdrawing groups as well as electron-donating groups, were used for synthesis of various 1,4-disubstituted-1,2,3-triazoles in high yields. The present procedure offers as short reaction time and simple reaction work up. This catalyst can be recovered by simple filtration and recycled several consecutive runs without any loss of its efficiency.     

Effect of metal salts on polymerization. Part I. Polymerization of vinylpyridine initiated with cupric acetate

The polymerization of vinylpyridine initiated by cupric acetate has been studied. The rate of polymerization was greatly affected by the nature of the solvent. In general polar solvents increased the rate of polymerization. Polymerization was particularly rapid in water, acetone, and methanol. The initial rate of polymerization of 4-vinylpyridine (4-VP) in a methanol–pyridine mixture at 50°C. is R_p = 6.95 × 10^?6[Cu¹¹]^1/2 [4-VP]² l./mole-sec. The activation energy of initiation by cupric acetate is 5.4 ± 1.6 kcal./mole. Polymerization of 2-vinylpyridine and 2-methyl-5-vinylpyridine with the same initiator was much slower than that of 4-VP. Dependence of R_p on monomer structure and solvent is discussed. Kinetic and spectroscopic studies led to the conclusion that the polymerization of 4-VP is initiated by one electron transfer from the monomer to cupric acetate in a complex having the structure, (4-VP)₂Cu(CH₃COO)₂.     

Novel method for catalyst immobilization using an ionic polymer: a case study using recyclable ytterbium triflate

A series of ionic polymers prepared by quarternization of cross-linked poly(4-vinylpyridine/styrene) (P/S) resins with several alkylating agents, including short-length PEG mesylate were used as polymeric supports to immobilize Yb(OTf)₃. The efficacy of the polymer-bound catalyst was examined in a Mannich-type reaction.