Synthesis and Characterization of Novel Hydrolytically Degradable Polyesters

Six novel hydrolytically degradable polyesters were synthesized from thiodipropionic acid(TDPA)and five diols by melt polycondensation,and characterized by FT-IR,1H NMR,gel permeation chromatography,differential scanning calorimetry and thermogravimetry analysis.The polystyrene-equivalent number-average(Mn)and weight-average molecular weight(Mw)of these polyesters ranged from 4900-11100 Da and 7900-20879 Da,respectively,with PDI values of 1.48-1.98.The melting point varied from 62.3-127.9℃,and the 50%mass-loss temperature ranged between 387-417℃.The degradation of these polyesters was studied in terms of relative weight loss in distilled water at different pH.Weight losses of 14%-26%were obtained at pH 7.0,26%-38%at pH 6.0,and 32%-43%at pH 8.3 over a 20-week period.The ecotoxicity study suggested that safety of the synthesized polyesters for the eisenia foetida.These results indicate that these polyesters have a combination of good thermal and degradability behaviors,which can be tailored through selection of the diol monomers used in the synthesis.

Preparation of Different Lights Irradiated ZnSe/GSH QDs and Their Interaction with BSA

Using L-glutathione(GSH) as a capping agent,Zn Se/GSH quantum dots(QDs) were prepared under microwave irradiation and irradiated under dark, ultraviolet light and incandescent light, respectively. The properties and interaction of different lights irradiated ZnSe/GSH QDs and bovine serum albumin(BSA) were studied systematically. The fluorescence(FL) spectra results reveal that the quenching mechanism are all the static quenching in nature. The quenching constant(Ksv) and binding constant(K) value of different irradiated Zn Se/GSH QDs and BSA all increased with the change of light types from dark to incandescent light and UV light. The number of binding site(n) is close to 1 at different temperatures. The lighting types influence the enthalpy and entropy changes. The Fourier transform infrared(FTIR) spectra indicate that the light induced GSH ligand will facilitate photocatalytic oxidation on the surface of ZnSe/GSH QDs. The circular dichroism(CD)results show that the α-helicity content of BSA decreases from 60.34%, 59.31%, to 58.79% under UV lighting,incandescent lighting and dark conditions. The interaction results of different lights illuminated ZnSe/GSH QDs with BSA by CD spectra method matches well with that by FL and FTIR spectra. That is, the interaction of ZnSe/GSH QDs and BSA from strong to weak is UV light, incandescent light and dark in sequence.

Synthesis and Characterization of Poly(terephthalic acid-2,5-furandicarboxylic acid-1,8-octanediol) Copolyester

Terephthalic acid,2,5-furandicarboxylic acid and 1,8-octanediol were adopted as monomers and antimony trioxide as catalyst,and poly(terephthalic acid-2,5-furandicarboxylic acid-1,8-octanediol) copolyesters identified as PEOT-x,where x is the mole fraction of furandicarboxylic acid in the samples,were synthesized by direct esterification.The molecular structure of the copolyesters was characterized by FTIR and 1H NMR spectroscopy.Gel permeation chromatography (GPC),differential scanning calorimetry (DSC),and thermogravimetric analysis (TGA) were used to characterize the molecular weight,molar mass dispersity,glass transition temperature,and thermal stability of the copolyesters,respectively.The mechanical properties of the samples were also investigated.The number-average molecular weight (M_(n)) of the samples varies from 9 700-18 800 g/mol,and molar mass dispersity (■=M_(w)/M_(n)) from 2.15-3.34.The initial decomposition temperature of the copolyesters is in the 332-356 ℃ range,with maximum decomposition rates at 390-410 ℃,while the glass transition temperature (Tg) varies from 0-33 ℃.Mechanical test shows that PEOT-10 has the highest tensile strength,while PEOT-90 has the largest tensile modulus and elongation at break.The experimental results show that these copolyesters can be synthesized with relatively high molecular weights,good thermal stability,and fair mechanical properties,which makes them excellent replacements for commercial polyesters,such as PET,and these properties can be tuned through the relative amounts of biomass monomer 2,5-furandicarboxylic acid used in the reactions.

Microwave Synthesis of CdTe/TGA Quantum Dots and Their Thermodynamic Interaction with Bovine Serum Albumin

The thioglycollic acid（TGA） as a capping agent, CdTe/TGA quantum dots（QDs） with excellent properties were synthesized under microwave irradiation. The TGA/Cd/Te molar ratios, reaction time, temperature and p H are the crucial factors for properties of QDs. The QDs were characterized by UVvis absorption and fluorescence spectra, transmission electron microscopy and Fourier transform infrared spectroscopy. The experimental results show that when the p H value is 11.5 and molar ratio of TGA：Cd：Te is 1.2：1：0.4 at 100 ℃ heating for 15 min, the resulted QDs exhibit a high fluorescence quantum yield of 78%. The fluorescence full width at half maximum（FHMW） of QDs is around 23 nm. The products are spherical with average size of 3-5 nm. There is a strong coordination effect between TGA and Cd2＋. Moreover, the results of interaction between as-made QDs and bovine serum albumin（BSA） suggest that the QDs-BSA binding reaction is a static quenching. The negative values of free energy（△G〈0） suggest that the binding process is spontaneous, △H〈0 and △S〈0 show that hydrogen bonds and van der Waals interactions play a major role in the binding reaction between QDs and BSA.

Synthesis of Agomelatine by One-pot Catalytic Hydrogenation and Acetylation with NiO

Nano-NiO and bulk NiO were prepared from Ni(AC)_2·4 H_2O by coordination precipitation using aqueous ammonia and by a solid state reaction, respectively. The nickel oxide particles were characterized by X-ray Diffraction(XRD) and scanning electron microscopy(SEM). The results indicate that nano-sized NiO has a crystal phase with a standard face-centered cubic lattice structure, with a mean particle diameter of about 10 nm. The evaluation of the activity of nickel oxide nanoparticles in the catalytic hydrogenation of 7-methoxy-1-naphthylacetonitrile was carried out. The results demonstrate the efficient synthesis of the title compound by a one-pot catalytic hydrogenation and acetylation with NiO. The NiO nanoparticles displayed superior catalytic activity in the synthesis of agomelatine in the one-pot reaction.The total yield of agomelatine is over 81.8% with a purity of 99.2%, as determined by HPLC. The structure of agomelatine was confirmed by IR, MS, and 1 H NMR analysis.

Degradable Polyesters based on Oxygenated Fatty Acid Monomer

A series of degradable polyesters was synthesized via melt polymerization of 3,6-dioxaoctane-1,8-dioic acid and five different diols,catalyzed by antimony trioxide(Sb_(2)O_(3)).The polymers were characterized by FT-IR and ^(1)H NMR spectroscopy,gel permeation chromatography(GPC)and differential scanning calorimetry(DSC)analysis.The polydispersity index(PDI=M_(w)/M_(n))of the polyesters ranged from 1.55 to 1.99,the weight-average molecular weight(M_(w))from 1.8×10^(4) to 3.2×10^(4) Da,the melting point from 63 to 123℃,and the highest decomposition temperature observed was 363℃.The influence of the structure of the polymer chain on hydrolytic degradability was investigated with tests performed at three different values of pH.The findings obtained provide useful insight for the molecular design and the synthesis of degradable polyesters.