最新刊期
卷 ， 期 11 ， 2009
- 摘要：The pyrolytic process and thermal degradation kinetics of UV cured multi thiol-vinyl silizane precursor was investigated by TGA-MS,FTIR,TGA-DTA.It was found that the pyrolytic processes consisted of three stages:280～430℃ (stage 1),430～560℃ (stage 2)and above 560℃ (stage 3).In the first stage,about 20% initial weight was lost,NH3,H2 and CH4 were released by transamination,dehydrcoupling and demethylate reaction.CO2,H2S,SO2 and a little amount of thiophene and 2-methyl thiophene were evolved during the first two stages,caused by —C(=O)—O— and C—S chemical bonds decomposed.In the third stage,about 7% initial weight was lost compared with about 9% was lost in the second stage,H2 and CH4 evolved due to dehydrcoupling between C—H and C—H (or Si—H and N—H) and Si—CH3 breakage.The kinetic parameters of thermal degradation were determined by Vachuska-Voboril and Friedman methods using data of TGA-DTA with different heating rates between 5 K/min and 40 K/min under highly purity N2 atmosphere.The results showed that (i) the apparent activation energy and reaction order increased in the first stage with the increase of functionality of thiol groups,and difference of these kinetic parameters in the second stage was not obvious; (ii) the final ceramic yield and activation energies at lower degradation degree of the copolymers decreased with increasing the content of thiol compound,whereas higher activation energies were obtained at higher degradation degree; the apparent activation energies of copolymers with the molar ratio of thiol to vinyl groups 1∶3 and 2∶1 were in the range of 175～195 kJ/mol and 95～118 kJ/mol (0.05≤α≤0.65),respectively.
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发布时间：2021-03-19 - 摘要：Silicone modified epoxy resins were prepared by polycondensation of polyphenylmethoxysilicone (PPMS) and polymethylphenylsilicone (PMPS) with E-20 epoxy resin.Oxirane ring and epoxy values were determined by Fourier transform infrared (FTIR) spectroscopy and HCl/acetone method.The data indicated that silicone oligomers were incorporated into epoxy resin with a random polycondensation and without involving the opening of the oxirane ring in the silicone modified epoxy structure.The influences of silicone contents on the heat-resistant properties of cured silicone modified epoxy resin systems were investigated by differential scanning calorimetry (DSC) and thermogravimetic analysis (TGA).The DSC data showed with increasing siloxane content in copolymers the glass transition temperature (Tg) lowered gradually.But when the mass ratio of epoxy resin to PPMS,PMPS was 7∶3,the Tg was 958℃ and 883℃,higher than those of unmodified epoxy resins systems by 9.0℃ and 1.5℃ respectively.The TGA data indicated that siloxane moiety exerts its thermal stability on the copolymer through dissipation of the heat,thus delaying thermal degradation of the copolymers.when the mass ratio of epoxy resin to PPMS,PMPS was 7∶3,the 50% weight loss temperature of degradation (Td) was 476.5℃ and 487.8℃,higher than those of unmodified epoxy resins systems by 58.3℃ and 69.5℃ respectively.In contrast to ED-30 cured system,the heat-resistance and toughness of EPMS-30 cured systems improved more obvious,and its film coatings also showed more excellent filming properties.
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发布时间：2021-03-19 - 摘要：Poly(diallyldimethyl ammonium chloride) (PDDA) and ferroelectric poly(vinylidene fluoride) (PVDF) composite ultrathin films on quartz glass prepared by electrostatic layer-by-layer self-assembly (SA) have been investigated.Physical measurements of deposited mass for each layer were performed with quartz crystal microbalance (QCM),while the morphology of ultrathin films was observed by atomic force microscope (AFM).And the element and composite structure of PDDA/PVDF were determined by X-ray photoelectron spectroscopy (XPS) and gracing incident X-ray diffraction (XRD),respectively.The surface resistivity and electric hysteresis loop of ferroelectric ultrathin films have been studied also.The results showed that the thickness of each layer for self-assembled PVDF ultrathin films on QCM substrate was about 7.5 nm,and the morphology of composite ultrathin films was uniform.The binding energy of F1s in composite ultrathin films was decreased 0.3 eV comparing with the poled PVDF films,which was caused by the distribution of negative charges as the re-dissolution of polymer.In addition,the surface resistivity was improved to over 1017 Ω#12539;cm for orderly self-assembly,and the remanent polarization was about 0.1 μC/cm2 for non-ferroelectric PVDF in PDDA/PVDF ultrathin films.
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发布时间：2021-03-19 - 摘要：In order to obtain the auxetic hydrogels with negative Poisson’s ratio,porous poly(vinyl alcohol) (PVA) hydrogels with different contents of PVA and surfactant (alkylphenol ethoxylates:OP) were prepared by methods of surfactants template and repeatedly freezing-thawing process,according to the microstructure and deformation mechanism of auxetic materials.The Poisson’s ratio and mechanical properties of porous PVA hydrogels were measured and calculated by digital speckle technique.The microstructure and pore morphology of porous PVA hydrogels were observed by optical and electron microscopy.The interrelation and variation of their parameters,including composition,Poisson’s ratio,compression modulus,volume modulus of pure and porous PVA hydrogels were compared and investigated.With the increasing of PVA and OP contents,the pore’s size became larger,and the Poisson’s ratio of porous PVA hydrogels decreased.The values of Poisson’s ratio of porous PVA hydrogels were directly proportional to the ratio of the compression modulus and volume modulus of the hydrogels.
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发布时间：2021-03-19 - 摘要：A novel strategy of radical polymerization of sodium 4-styrenesulfonate (NASS) on the surface of carbon black (CB) in solid state is developed to prepare water-dispersible carbon nanoparticles (PNASS-CB).A high performance of natural rubber latex (NRL)/PNASS-CB composite is gained by latex compounding technique.Proton nuclear magnetic resonance (1H-NMR) results show the presence of PNASS chains on the surface of CB,and the encapsulating ratio is 8.1 wt% and grafting ratio is 2.5 wt% by TGA.The surface energy of PNASS-CB was decreased, the interaction between carbon black was weakened,and the carbon-rubber interaction was enhanced.And the carbon nanoparticles are uniformly dispersed in the composite as the result of RPA.When compared to the NRL/pristine CB composite,the tear strength,tensile strength and elongation at break of the obtained composite are increased by 85%,30% and 20%,respectively.
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发布时间：2021-03-19 - 摘要：A series of anionic waterborne polyurethane emulsion modified by epoxy resin were successfully prepared by the reaction of polycaprolactone diols (CAPA),isophorone isocyanate (IPDI),hexamethylene-1,6-diisocyanate (HDI) and epoxy resin (E-44) as crosslinker.Solidified films of the waterborne polyurethane were prepared by casting emulsions on Teflon surfaces.Fourier transform infared spectrometer (FTIR) and thermogravimetry analysis (TGA) were used to characterize the structure of the polyurethane.The mechanical properties and water contact angle of the cast films were also measured.The surface roughness and surface morphology of the films of waterborne polyurethanes were observed by atomic force microscopy (AFM).The particle size and distribution of the resultant polymer emulsions was tested by the dynamic laser light scattering (DLLS).FTIR indicates that epoxy group and hydroxyl group of E-44 both reacted with the polyurethane prepolymer.TGA indicates that the crosslink of E-44 with polyurethane increased thermal stability of the modified polyurethanes.It was found that the tensile strength of films of modified polyurethane increased and the elongation at break decreased with increasing E-44 content,the water contact angle increases with increasing w(E-44),the smoothness of solidified films of waterborne polyurethane decrease when modified by E-44,resulting in water repellence functions.DLLS showed that the particle size of emulsion increased with increasing w(E-44).In order to obtain stable polyurethane emulsions and solidified films of waterborne polyurethanes with improved mechanical properties,the proper w(E-44) is 10%.
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发布时间：2021-03-19 - 摘要：Zinc tetraphenylporphyrin (ZnTPP) was bound on the side chains of the copolymers of 4-vinylpyridine and styrene (P(4VP-co-St)) via axial coordination reaction,and the porphyrin-functionalized polymer ZnTPP-P(4VP-co-St) was prepared.The structures of ZnTPP-P(4VP-co-St) were characterized with FTIR and 1H-NMR spectra.The effects of time and temperature on the bonding degree of ZnTPP on P(4VP-co-St) were analyzed.Moreover,the electronic absorption and fluorescence emission spectra of ZnTPP-P(4VP-co-St) were mainly studied,and its photo-physical behaviors were described in depth.The experimental results show that the porphyrin-functionalized macromolecules ZnTPP-P(4VP-co-St) can be favorably prepared through the axial coordination reaction between the side pyridine groups of the copolymer P(4VP-co-St) and the metalloporphyrin ZnTPP,and the lower the temperature,the higher the bonding degree of ZnTPP is.The macromolecular axial coordination compound ZnTPP-P(4VP-co-St) possesses the characteristic electronic absorption and fluorescence emission spectra of ZnTPP,and at the same time,it exhibits the characters of axial coordination compounds.As compared with the small molecular ZnTPP,all of the absorption and emission spectra of ZnTPP-P(4VP-co-St) exhibit obvious red shift.In addition,the behavior of the axial coordination compound ZnTPP-P(4VP-co-St) exhibits a polymer effect in its photophysical behavior.As the bound amount of ZnTPP on the side chain of polymer P(4VP-co-St) is increased,the energy transfer between the adjacent side ZnTPP units will be produced,resulting in the slight weakening of the fluorescence emission.
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发布时间：2021-03-19 - 摘要：Two wide band gap alternating copolymers (PFOTPP1 and PFOTPP2) derived from 9,9-dioctylfluorene and 2,6-bis(3-bromophenyl)-4-phenylpyridine (TPP1),2,6-diphenyl-4-(3,5-dibromophenyl)pyridine (TPP2) were synthesized by Suzuki coupling reaction.The resulted polymers are soluble in common organic solvents such as toluene chloroform etc.The maximal absorption peaks of PFOTPP1 are around 325 nm in THF solution and 329 nm in solid thin film,The maximal absorption peaks of PFOTPP2 are around 329 nm in THF solution and 331 nm in solid thin film.PFOTPP1 and PFOTPP2 show two photoluminescence peaks around 367 nm and 383 nm in THF solution,and around 395 nm and 413 nm in solid thin film,respectively.The LUMO levels of PFOTPP1 and PFOTPP2 are around -253 eV and -264 eV.The glass-transition temperature of PFOTPP1 and PFOTPP2 is around 145℃ and 152℃,respectively.The thermal degradation temperature of PFOTPP1 and PFOTPP2 is above 400℃.It indicates that the energy levels of the polymers are widened and the LUMO levels of the polymers are increased with introducing the triphenylpyridine unit into the polyfluorene back bone.
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发布时间：2021-03-19 - 摘要：The effect of thermal history on the melting behavior of nylon 1212 has been studied by differential scanning calorimetry (DSC).Two or three melting peaks were observed on DSC curves at different thermal history.The mechanism of melting peaks of nylon 1212 was analyzed according to the theory of polymer crystallization.Lower temperature melting peaks (PⅠ) in DSC curves were mainly attributed to melting of minicrystal or lamellar crystal which developed from nylon 1212 annealed for 120 min at different temperatures.The peak temperature of these peaks is low,and their area is small.The main melting peak (PⅢ) is the melting of perfect crystals which are formed in a recrystallization process of the polymer after PⅠ and PⅡ.The value of main peak temperature is much higher and the area is much larger.The melting peak (PⅡ) might be developed from melting of crystals which formed during quenched process of nylon 1212. The position of melting peak changed slightly with different heating rate,which indicates that these crystals have similar form.Increasing crystallization time is favorable for perfect crystals formation.The sample annealed at two different temperatures exhibits two additional melting peaks.Temperatures of these additional melting peaks are higher than annealing temperatures.Moreover,the position and area of additional peak reduced with the annealing temperature decreasing.The equilibrium melting temperature of nylon 1212 was determined as 202.8℃ by Hoffman’s method according to results of isothermal crystallization.
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发布时间：2021-03-19 - 摘要：A new and simple method to prepare the monodisperse microbeads was developed for soluble polymers.Using a microchannel,we generated the uniform droplets by pushing the dispersed phase into the continuous phase and then solidified them by solvent-evaporation or gelation to obtain the PLA and sodium alginate microbeads.The microchannel was fabricated in our lab,and all of the materials were commercially produced.By using a frequency-modulation oscillator to help evaporation,the droplets can be solidified within 2 h,and especially the surface of the microbeads was smooth,and small pores with diameter of 1～2 μm were well-dispersed.By controlling the flow rates of the continuous phase conveniently,we could adjust the sizes of the microbeads.The diameters of the microbeads decreased from 460 μm to 342 μm when we increased the flow rates from 100 μL/min to 900 μL/min,and the lowest coefficients of variance of the microbeads was 2.16%.Also we studied the effect of the different continuous phases on the size of the microbeads,and it was believed that the size of the microbeads can be controlled by using different surfactants or mixing them in the continuous phase.
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发布时间：2021-03-19 - 摘要：To prepare environmentally resporsive(ER) copolymers which are suitable for fabr ication of ER polysulfone (PSF) membranes,we designed and synthesized the PSF copolymers with poly(acrylic acid)(PAA) and poly(N-isopropylacrylamide (PNIPAAm) side chains,i.e.PSF-g-PAA and PSF-g-NIPAAm,respectively.These two comb-like copolymers were synthesized via ATRP by using a chloromethylated polysulfone as macroinitiator.The molar fraction of PAA and PNIPAAm in the resultant copolymers estimated from 1H-NMR is 0.538 and 0.896,respectively.In using as additives for PSF membranes prepared by the phase inversion process,the comb-like copolymers segregate to the membrane surfaces,delivering improved porosity,average pore diameters,hydrophilicity,and ER properties compared to pure PSF membranes.For instance,20 wt% PSF-g-PAA/PSF and 20 wt% PSF-g-PNIPAAm/PSF blend membranes can be completely wet by water within 35 s and 90 s,respectively.The flux of the aqueous solution through the 20 wt% PSF-g-PAA/PSF membrane decreases with increasing the solution pH valuse from 1 to 6.The water permeation rate through the 20 wt% PSF-g-PNIPAAm/PSF membrane increases with increasing water temperature from 25℃ to 60℃.
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发布时间：2021-03-19 - 摘要：Cylindrical brushes with poly(t-butyl acrylate)-b-poly(fluoroalkyl acrylate)(PtBA-b-PFA) semi~fluo~ri~na~ted diblock copolymer side chains,were successfully prepared via grafting from technique using atom transfer radical polymerization(ATRP).Poly(2-(2-bromoisobutyryloxy)ethyl methacrylate) was used as a ma~cro~ini~tia~tor.The formation of well-defined brushes was confirmed by GPC and 1H-NMR.Then the selective hydrolysis of the PtBA block of side chains results in the amphiphilic semifluorinated cylindrical brushes PBIEM-g-(PAA-b-PFA).The characteristic cylindrical structure of the brush PBIEM-g-(PAA-b-PFA) was directly visualized on mica by atomic force microscopy (AFM).Though a narrow length distribution (PDI=1.08) of a macroinitiator PBIEM was obtained,the total length ln of brushes was varied within 54～72 nm.By adjusting the proper ratio of mixing solvents in the spinning-coating process on mica,the core and the shell can be visualized independently by AFM.
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发布时间：2021-03-19
Research Article
- 摘要：The microcapsules containing wax encapsulated by poly(methyl methacrylate-co-acrylic acid) (P(MMA-co-AA)) with diameter in the range of 1～5 μm were fabricated by radical polymerization around the wax in a dispersion system.The chemical structure,morphology and thermal behavior of the microcapsules were studied by FTIR,phase-contrast optical microscope,SEM and thermal analysis.The thermal properties of the microcapsules revealed that the content of the core material was up to about 70%,and the microcapsules had a high latent heat (ca. 99 J/g).The dispersed microcapsules can be used as a latent functional thermal fluid to improve the heat transfer efficiency in the fields of refrigeration and air-conditioning.
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发布时间：2021-03-19 - 摘要：A new method for preparing crosslinked fibrous gelatin membrane was developed in order to circumvent the disadvantages of traditional methods for crosslinking electrospun gelatin fibers.Through a series of experiments,the stable window of one-step electrospinning was found as 3 mL of 10% gelatin solution in TFE with 40 μL glutaraldehyde added.SEM micrographs showed the diameter of the electrospun fibers ranged from 1 μm to 1.5 μm and was thicker than that of the noncrosslinked gelatin fibers.Furthermore,a phenomenon of false core-shell fibers was observed,which might be attributed to the rapid evaporation of glutaraldehyde at the vicinity of the fiber surface.Rheological behavior of the electrospinning solution was studied,indicating that viscosity had a drastic rise upon adding glutaraldehyde and maintained slow increase after 10 min.It was also found that a fibrous structure of the electrospun gelatin membrane could still be preserved after soaked in distilled water at 37℃ although the membrane suffered from about 10% weight loss.The one-step electrospinning method should be useful in the fields of biomedical engineering,such as tissue engineering and wound healing.
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发布时间：2021-03-19 - 摘要：The objective of this work was to develop a kind of new polymer with high hydrophobicities and good thermal stabilities.The introduction of fluorine into poly(arylene ether) is regarded as an effective way.A partially fluorinated poly(arylene ether) containing fluorenyl groups was successfully synthesized by aromatic nucleophilic substituting polycondensation from bisphenols and decafluorobiphenyl at 120℃,and the structure of the polymer was characterized by 1H-NMR.Number-average molecular weight characterized by GPC was 4.63×104 Da.The DSC and TGA measurements of the polymer were performed under a nitrogen atmosphere,and the results showed that the polymer exhibited good thermal stabilities with high Tg of 271℃ and 5% mass loss at 420℃.Moreover,the polymer was very soluble in common organic solvents,such as CH2Cl2,CHCl3,dimethyl sulfoxide,N,N′-dimethylacetamide,and could be readily cast into tough and smooth films from solutions.The films also showed high contact angles of water.Contact angle of the film cast by CHCl3 is 102°.Contact angle of the film cast by THF is 107°,which is close to that of Teflon (112°),indicating that the polymer has high hydrophobicities.The polymer synthesized may have a promising prospect in microelectronic devices,such as the substrate for printed boards,and insulating materials as interlayer dielectrics and intermetal dielectrics.
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发布时间：2021-03-19 - 摘要：A sample of polyvinyl acetate with Mn=1.48×106 (by GPC) was obtained by bulk photo-polymerization,and then it was conversed into poly(vinyl alcohol) with Mη=2.3×105,as HMWPVA thereafter.The specimens of ice strengthened by HMWPVA were prepared per following procedures:(1) the aqueous solutions of HMWPVA with predetermined concentrations were prepared and then degassed; (2) poured the above solutions in models and then put them in a -18℃ refrigerator for over 48 h.The tensile and compression testing was performed at -18℃.It showed that with addition of 3% (mass fraction) HMWPVA,the values of the tensile strength,elongation at break,compressive strength and compressive modulus of ice were 11.7,3.5,2.3 and 2.1 times of those of pure ice,respectively.It implied that there was a strong dependence of the tensile strength on the molecular weights of the PVA.Furthermore,the addition of HMWPVA increased the melting time,for example,the melting time of pure ice is about 5 min at 29℃,but the samples with 2%,3% and 4% HMWPVA are 25 min,60 min and 240 min,respectively.
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发布时间：2021-03-19 - 摘要：Drug-loaded nanofiber membrane was successfully prepared using electrospinning process with helicid as the poorly water-soluble model drug and polyvinylpyrrolidone (PVP K30) as the filament-forming matrix.Polarization microscopy (PM) and scanning electron microscopy (SEM) were taken to observe the morphology and structure of the nanofibers.Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) were carried out to determine the physical status of the drug in the nanofibers.Fourier-transform infrared spectroscopy (FTIR) was conducted to characterize the interaction between the drug and the polymer.Results from the PM and SEM studies showed that the nanofibers had a very well uniform structure with a diameter of 400～600 nm and very smooth fiber surface.DSC and XRD results co-demonstrated that helicid lost its original crystal structure,the needle or long rod shape,but highly distributed in the nanofibers due to the forming of chemical complexes between the PVP K30 and the helecid molecules.FTIR spectra clearly showed that the main interactions between PVP and helicid were hydrogen bonding,which was formed between the carbonyl groups of PVP K30 and the hydroxyl groups of helicid and resulted in the firm existence of drug in the fibers.In vitro wetting and dissolution tests showed that the nanofiber membranes were able to absorb water and dissolve on the water surface in 13.7 s through the “polymer-controlled" mechanism,exhibiting great potential to provide strategies for resolving one of the most difficult problems in pharmaceutics——the dissolution and absorbance of poorly water-soluble drugs,and offer novel approaches for preparing oral fast dissolving drug delivery systems or fast acting dosage forms.
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发布时间：2021-03-19 - 摘要：For improving third-order optical nonlinear properties of metallophthalocyanine films,an thin composite film with alternating layers containing anionic tetra sulfonated phthalocyaninavanadium (VOTsPc) and cationic polyethylenimine (PEI) has been prepared by the electrostatic self-assembly technique.The alternating multilayer assemblies of VOTsPc/PEI were characterized by UV-Vis spectroscopy,showing the regularly consecutive adsorption process.Surface morphology of the fabricated VOTsPc/PEI thin film was studied by atomic force microscopy technique.The result showed that the film surface was smooth and homogeneous.The closely packed nanoparticles,with the average diameter of 75 nm and the mean interface roughness of 4.406 nm,can be easily seen on the film surface uniformly.By using a frequency-doubled Q switched Nd:YAG pulse laser system with ns/ps laser pulse,the third-order optical nonlinear properties of the film were studied by Z-scan measurements at wavelength of 532 nm with 4 ns pulses.By simulation and calculation of the experimental data,the nonlinear refractive index,n2 value and the nonlinear absorption coefficient,β value of a 30-bilayer VOTsPc/PEI film is 4.87×10-6 esu and 1.2×10-5 m/W,respectively.The third-order nonlinear susceptibility χ(3) value of the film is 1.57×10-6 esu by calculation.The VOTsPc/PEI film shows strong nonlinear reverse saturable absorption performance and has broad application prospects.
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发布时间：2021-03-19
Research Bulletin
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