最新刊期
卷 ， 期 4 ， 2011
- 摘要：Poly(N-isopropylacrylamide)-b-poly(L-glutamic acid) (PNIPAM-b-PLGA) block copolymers were synthesised,and polymeric micelles were prepared at high temperatures.The polymeric micelles were employed to control the crystallization of calcium carbonate (CaCO3) by the gas diffusion method.Scanning electron microscopy and X-ray powder diffraction were used to study the CaCO3 morphologies and polymorphs.When the concentration of micelles is high,nest-like super-structures with diameters about 50 m were observed.The super-structures composed of aragonite fibres with large ratios of length to diameter.And droplet-like growth points were frequently found at the end of fibres.While a lower concentration of micelles led to the formation of irregular vaterite particles.From the time-resolved experiments,the mechanism of crystals formation was proposed.First,polymer-induced liquidprecursor (PILP) amorphous CaCO3 was induced by the micelles,and then the precursors grew into one-dimensional fibres through an attachingsolidifying process.For the strong interaction between copolymers and calcium ions,a higher concentration of micelles could retard crystallization of the precursors and induce the formation of aragonite fibers.While lower concentration of micelles made the crystallization less inhibited,and thus led to the formation of vaterite particles.Control experiments showed that such PILP process could not be induced by PNIPAM,PLGA homopolymers and PNIPAM-b-PLGA block copolymers dilute solution (25℃,no well defined aggregates were formed).Therefore,PNIPAM-b-PLGA micelles play a crucial role in the formation of CaCO3 liquid-like precursor precursors and aragonite fibre growth.The present investigation of the influence of PNIPAM-b-PLGA micelles on CaCO3 crystallization is helpful for the understanding of the PILP process and fabricating other fibrous inorganic materials.关键词：Micelles;Calcium carbonate;Liquid precursor;Aragonite;Vaterite
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发布时间：2021-03-19 - 摘要：采用反相悬浮聚合技术，合成了茶碱模板酚醛吸附树脂和非模板酚醛吸附树脂，比较了两种树脂对茶碱的吸附状况.结果表明，对茶碱的吸附数据符合Langmuir方程，吸附属于单分子层吸附.在一定浓度范围内的吸附数据符合Freundlich方程，表明吸附是优惠吸附.Scatchard分析表明茶碱模板酚醛树脂具有特定的高亲和性吸附位点，其离解常数和最大吸附量为Kd1=0.129 mmol/L，Qmax1=138 mol/g，低亲和性吸附位点的离解常数和最大吸附量为Kd2=0.433 mmol/L，Qmax2=184 mol/g.在吸附的初始阶段,吸附速率数据与半经验吸附速率方程很吻合,证实吸附茶碱是粒扩散控制过程.在动态条件下，浓度为2.00 mmol/L的茶碱溶液以3 BV/h的流速流经茶碱模板酚醛吸附树脂床时，在第24 BV出现穿透；用1 mol/L的盐酸以1.5 BV/h的流速进行洗脱，在4BV的洗脱率达到97.2%，说明该树脂具有良好的洗脱性能.关键词：Molecularly imprinting;Theophylline;Phenolic resin sorbent;Inverse suspension polymerization;Adsorption
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发布时间：2021-03-19 - 摘要：Free radical meltgrafting of the multimonomer system of maleic anhydride (MAH)/styrene (St) onto high density polyethylene (HDPE) prepared by a singlescrew extruder was studied.It was found that the addition of St monomer could significantly improve the MAH grafting level of the grafted HDPE.With increasing the St concentration,the graft degree of MAH first increased and then decreased a little.The maximum MAH grafting degree and the minimum melt flow rate were obtained when the molar ratio of MAH to St was approximately 1∶1.The higher the graft degree,the smaller MFR value was,suggesting that the grafted PE chains induced intermolecular entanglements.The mechanical properties of the grafted polymer with the addition of small portions of St monomer were better than those of the neat HDPE in this case.The mechanism of the multimonomer melt grafting HDPE system was also discussed.It was proposed that MAH and St interacted and copolymerized with each other in the melt grafting system.The grafting of StMAH copolymer (SMA) onto HDPE greatly increased the grafting degree of the grafted HDPE.When the amount of St is larger than MAH,St would be first grafted onto the PE backbone,inhibiting the grafting of SMA.Besides,the crosslinking of PE was well depressed due to the increase of graft degree in the multimonomer melt grafting systems.And no obvious gel was obseved in the reflux process.
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发布时间：2021-03-19 - 摘要：The confined crystallization behavior of the dendritic block copolymer poly(-caprolactone)-b-polystyrene (D-PCL-b-PS) was investigated under asymmetric chain ends restriction of PCL blocks. At the beginning, the block copolymer was synthesized through combination of ring opening polymerization (ROP) and atom transfer radical polymerization (ATRP). The crystallizability of PCL block varied significantly with this specific dendritic molecular structure. During the nonisothermal crystallization process, only a fraction of slightly restricted PCL blocks could form crystals through extinct cold crystallization, and the significantly restricted PCL blocks was unable to crystallize during the limited cold crystallization process. Further isothermal crystallization was carried out to make samples completely crystallize. It was found when the crystallization temperature was below 30℃, double melting peaks were observed on the DSC curves of the samples, with the lower peak at nearly 40℃ and the higher at 50℃. The two peaks shifted to higher temperature regions and got closer with increasing isothermal crystallization temperature. When the isothermal crystallization temperature reached 40℃, the two melting peaks were not distinct any more. The lower melting point was corresponding to the fusion of the unperfect crystals formed by significantly restricted PCL blocks, and the higher melting point was ascribed to the melting of the relatively well-developed crystals formed by slightly restricted PCL blocks. A model indicating the conformations of PCL blocks under different degrees of chain end restriction was suggested.
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发布时间：2021-03-19 - 摘要：The effect of shear flow on the formation and architecture of the multicompartment wormlike micelles of PS720-b-P2VP200-b-PEO375 (the subscripts indicate the numbers of the repeat units of the blocks) copolymer has been investigated by transmission electron microscopy (TEM) and field emission scanning electron microscopy (SEM).For a system with 1 wt% copolymer concentration and 13 wt% water concentration in THF/water,the micelle morphology observed by TEM changed from spheres to shuttlelike micelle aggregates,then to multicompartment wormlike micelles and finally to spheres as the stirring rate increased from 200 r/min to 2200 r/min.It was found that the micelles would change to worms again as the stirring rate changed from 200 r/min or 2200 r/min to 1500 r/min,indicating that the wormlike micelles were independent on initial phases.SEM observations revealed that the wormlike micelles were composed of overlapped disks,which was also confirmed by stain technology.Further research indicated that the formation of wormlike micelles underwent three stages.The triblock copolymer first self-assembled into small spheres,then these small spheres joined together to form intermediate shuttlelike structures and finally the spheres within the shuttlelike structures rearranged and underwent further adjustment to form the worms.Therefore,the multicompartment wormlike micelles formed as a result of secondary self-assembly of the spheres under shear flow.
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发布时间：2021-03-19 - 摘要：The optical waveguide (OWG) sensor used consists of a substrate,waveguide layer (K+ion exchanged layer or tindiffused OWG) and thin top layer (sensing layer).The semiconductor laser beam (630~680 nm) was introduced into the OWG using a prism coupler (glass prism,n = 1.78; and a matching liquid,diiodomethane,n = 1.74),and it emerged from another prism coupler.The intensity of the output light was monitored by using a photomultiplier detector,and the output light intensity was recorded by a computer.Pure air that functioned as a carrier and dilution gas flowed through the cell at a constant rate of 40 mL/min in order to transfer the xylene gas to the sensor.All measurements were made at room temperature.Pure PVA and Vc embedded PVA were chosen as sensitive materials,the PVA film/tin-diffused glass OWG and VC-PVA thin film/tin-diffused glass OWG were fabricated by spin- coating methods.We used this two OWG sensors to detect xylene gas,and the experimental result shows that the PVA film/tin-diffused glass OWG exhibited a good response to xylene gas,its detection range was 10-4～10-7.While the Vc-PVA thin film/tin-diffused glass OWG exhibited higher sensitivity and larger response range (this OWG sensor has a considerable response to 10-8 of xylene gas).These sensors were also characterized by high sensitivity,simple structure and were easily fabricated.关键词：OWG gas sensing element;VCPVA thin film;Xylene;Gas sensing properties
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发布时间：2021-03-19 - 摘要：Functional polystyrenes (ASAPS) with salicylic acid (ASA) ligands on side chains were prepared with chloromethylated polystyrene (CMPS) as starting substance via twostep polymer reactions, phasetransfer catalytic esterification with sodium glyoxylic acid as reagent and Schiff reaction with 5\|aminosalicylic acid in a homogeneous system. The functional polymer ASAPS was allowed to be coordinated and chelated with Eu(Ⅲ) ion, obtaining polymerrare complex ASAPSEu(Ⅲ). The luminescence property of this complex was preliminarily examined. The experimental results show that with the phasetransfer catalysis action of quaternary ammonium salts, the esterification reaction between the chloromethyl groups of CMPS in organic phase and sodium glyoxylate in water can be carried out effectively, forming a lineartype and aldehyde (AL) groupfunctionalization polystyrene ALPS. The structure of the phasetransfer catalysts and the polarity of the solvents affect the phasetransfer catalytic reaction greatly. The complex ASAPSEu(Ⅲ) possesses the characteristic fluorescence emission, and a remarkable antenna effect can be produced.
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发布时间：2021-03-19 - 摘要：Pyrrole (Py) and pyrrole derivative with carboxyl groups,1\|(2\|carboxyethyl)pyrrole (PyCA),were copolymerized with 6-(1H-pyrrol-1-yl)hexane-l-thiol(PHT) self-assembled on Au surface by chemical polymerization to form a layer of the copolymer film,(poly(PHT-co-Py-co-PyCA)).The carboxyl groups of (poly(PHT-co-Py-co-PyCA)) were activated using N-(3-dimethylaminopropyl)-N-ethylcarbodilimide (EDC) and N-hydroxysuccinimide (NHS) and transferred to amide bonds by reacting with the amino groups in the amino-labeled probe DNA.In consequence,amino-labeled DNA could be immobilized onto the copolymer.Afterwards,the complementary target DNA can be hybridized with probe DNA.The chemical structure and components of poly(PHT-co-Py-coPyCA) before and after DNA immobilization were investigated by Fourier-transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS).The electrochemistry properties and the variation of the charges of copolymer film before and after DNA anchor were characterized by cyclic voltammetry and electrochemical impedance spectra.To detect the immobilization behavior of DNA,surface plasma resonance was used.The result revealed that it is a slow process for DNA anchoring onto the copolymer matrix and the electrochemical activity and the charges transfer decreased after DNA immobilization/hybridization.Furthermore,there is no non-specific adsorption between target DNA and copolymer.It could supply the theoretical and experimental base for the application of copolypyrrole film functionalized with carboxyl groups as DNA sensors.关键词：Copolymer conducting;Electrochemical impedance spectra;1-(2-Carboxyethyl)pyrrole;DNA immobilization/hybridization
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发布时间：2021-03-19 - 摘要：The aniline was inarched on the surface of the carbon nanotubes (CNTs) by a series of organic chemistry reactions (carboxylic acid reaction,chloride reaction and amidation reaction).Then,the CNTs with the aniline and the other aniline were polymerized in the sulfuric acid solution on the surface of stainless steel electrode by electrochemistry cyclic voltammetry deposition method,namely a combination method.The micro-structure and groups of sample were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy.The electrochemical performances of obtained materials were characterized by cyclic voltammetry and galvanostatic charging/discharging testing.In order to study the obtained composite merits from the combination method,electrochemistry deposition method was used to prepare pure polyaniline (PANI) and CNTs/PANI composite at the same experimental conditions.The experimental results showed that the CNTs/PANI composite by the combination method had a better porous structure; the diameter of the CNTs/PANI composite was 150~250 nm.Moreover,the CNTs/PANI composite made by the combination method had the highest capacitance,up to 366 Fg-1 with 22 Am-2charging-discharging current density,and capacitances of the CNTs/PANI and the PANI prepared by the electrochemistry deposition method were 327 and 205 Fg-1,respectively.And the composite from the combination method had the best stability (capacitance decline was under 5% after the 200 cycle times and that of the CNTs/PANI and the PANI prepared by the electrochemistry deposition method was up to 7% and 9%,respectively).
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发布时间：2021-03-19 - 摘要：N-octadecyl maleamic acid (ODMA) as gelator self-assembled in solvent mixture of -hydroxyethyl methacrylate,methylacrylic acid and polyethylene glycol dimethacrylates-200 in the presence of 3-cholesteryloxycarbonylpropanoic acid (COPA) as template molecule,and turned them into thermally reversible polymerizable organogels.The resultant organogels were subsequently polymerized by in situ UV irradiation.The molecularly-imprinting polymerized organogels were obtained after removal of the template molecules through acetonitrile extracting.The cholesterol molecularly imprinted polymerized organgels (MIPO) showed significantly higher affinity for cholesterol than that for non-imprinted polymerized organgels (NIPO) in water/THF mixture (5∶6,V/V).The selectivity experiment indicated that the adsorption amount of MIPO for cholesterol (18.9 mg/g) was higher than that for stigmasterol (4.5 mg/g) and testosterone (3.6 mg/g) within 3 h since the selectivity was based on the specific binding of cholesterol to recognition sites formed in polymers.The adsorption capacity for cholesterol onto MIPO was found to increase and then decrease,but for stigmasterol and testosterone which was decreased with the increase of ODMA in organogel.The higher concentration of COPA in organogel would result the decrease of the adsorption capacity for cholesterol,but the adsorption capacity for stigmasterol and testosterone remained nearly constant.However,these results could be attributed to the high density of polymer network and stability of imprinted holes.关键词：Organogels;Molecular imprinting;Cholesterol;Selectivity adsorption
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发布时间：2021-03-19 - 摘要：Cellulose hollow fiber membranes (CHFMs) were prepared by a new dissolving method.The influence of coagulation bath temperature on the morphology and properties such as crystallinity degree,mechanical strength and gas permeation performance of CHFM was systematically investigated.The results showed that with the increase of coagulation bath temperature,the morphology of asymmetric cellulose hollow fiber membranes would become much looser,and more large fingerlike pores could be found across the section.At the same time,crystallinity degree almost showed no change and mechanical strength became worse obviously.As a result gas permeation performance of dry CHFMs would increase dramatically with the coagulation bath temperature and show obvious Knudsondiffusion selective mechanism.While for wet CHFMs,permeation rates for all gases would decrease sharply and interestingly for CHFMs from coagulation bath temperature of 0℃ and 20℃ carbon dioxide became the fastest gas because of the permeation mechanism had changed to solution selective in wet CHFMs.While for CHFMs from coagulation bath temperature of 40℃ and 60℃,this solution selective effect cannot be found because of their much looser structure.关键词：Cellulose hollow fibre membrane;Coagulating bath;Gas separation;Knudson-diffusion;Solution-diffusion
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发布时间：2021-03-19 - 摘要：The effects of terpolymer liquid crystalline poly(ester imide) (PPDI) on the structure and properties of its blend with semicrystalline polymer,poly(ethylene terephthalate) (PET) were studied.The PPDI was synthesized by our lab.The blend systems were prepared by melt blending,and the content of PPDI ranged from 0/100 to 10/90. Differential scanning calorimetry (DSC),wide-angle X-ray diffraction (WAXD) and dynamic mechanical property analysis (DMA) were used to study the crystalline behavior,crystalline structure and dynamic mechanical properties of the blend system,as well as the miscibility of PPDI and PET.Results showed that the addiction of liquid crystalline terpolymer PPDI had strong effect on the crystalline behavior and crystalline structure of PET,which acted as heterogeneous nuclear agents,therefore increasing the initial crystallization point and crystallization rate of PET,and was of benefit to the increase of the degree of crystallinity and the perfection of crystallization.The blend systems show only one glass transition temperature (Tg),and the Tgs are much higher than the theoretical results calculated by using Fox equation.Dynamic mechanical properties showed that storage modulus of the blend systems was higher than that of PET,and increased with the content of PPDI.These mean that PPDI has a reinforcing effect on PET. The thermal stability of the blend systems is a little higher than that of pure PET.关键词：Liquid crystalline poly(ester imide);PET;Blend;Structure;Properties
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发布时间：2021-03-19 - 摘要：Dihydroxyl containing glyceryl methacrylate (GM),a coupling agent in polyurethane (PU) modification by acrylic polymers (PAC),was first synthesized through hydrolysis of glycidyl methacrylate,and its structure was confirmed through 13C-NMR,FTIR and gas chromatography.GM was then reacted with isocyanate terminated PU prepolymers to input vinyl group with objective to conduct graft-polymerization with acrylics in a subsequent step,and to get acrylic modified polyurethane (PU-AC) latexes.Hydroxyethyl acrylate (HEA) was also used in the same way as GM,and the results were compared.The results showed that,under the same reaction temperature for PU with the 2 coupling agents,higher NCO conversion combined with a lower grafting of PU to PAC was observed with GM.As regard to the influence of temperature in the reaction of PU with the coupling agents,results indicated that both NCO conversion and PU grafted to PAC in the final latex polymers were increased with increasing the reaction temperature,regardless of using GM or HEA.The molecular weight of the PU prepolymers remained nearly constant upon reaction of PU with HEA,and a slight increase in the particle size in the final PUAC latex was detected.However,with GM,the impact of this reaction temperature on the PU prepolymers was different from that with HEA.With GM,when OH/NCO molar ratio was inferior to 1,the molecular weight of the vinyl attached PU increased,and a decrease was detected when OH/NCO was superior to 1.For both coupling agents,the grafting of PU to PAC was enhanced with more coupling agent when OH/NCO was inferior to 1,and this enhancement was nearly disappeared when OH/NCO molar ration was superior to 1.关键词：Polyurethane modification;Glyceryl methacrylate;Hydroxyethyl acrylate;Polyurethane grafting
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发布时间：2021-03-19 - 摘要：The effect of polydispersity on the self-assembly of amphiphilic diblock copolymer in a selective solvent was studied by means of Monte Carlo simulation.The polydisperse diblock copolymer system was constructed via the mixing of three amphiphilic diblock copolymer chains different in length,i.e.,A2B2,A2B6 and A2B10.The simulation results show that the micelle morphologies formed by AB diblock copolymers in a selective solvent changed from vesicle to lamellae,then to spheres with an increase in polydispersity index (PDI) from 1.0 to 1.4- Through the analysis of the variations of the number and fractions of free single chains with the increase of PDI in each system,it is found that the number of short chains (i.e.A2B2) which aggregate into micelles increased with an increasing PDI.Meanwhile,the self-assembly processes of diblock copolymers with different PDI in a selective solvent reveal that the increasing number of short chains can increase the surface area of the micelles,leading to a disadvantage for the fusion between small micelles during the self-assembly.The increase of the surface area of micelles is the main reason of the morphological transition from largesized vesicles to small-sized spheres when the PDI is increased.These simulation results indicate that the micelle morphologies and their mutual transitions in a selective solvent can be tuned by the control of the polydispersity of AB diblock copolymers.关键词：Polydispersity;Amphiphilic diblock copolymer;Self-assembly;Monte Carlo simulation
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发布时间：2021-03-19 - 摘要：With no any surfactant and in the presence of casein (CA),nano-sized core/shell latex particles based on methyl methacrylate (MMA)/CA with about 150 nm in diameter,determined by light scattering,were prepared through emulsion polymerization of MMA using tert-butyl hydroperoxide(TBHP) as initiator.The designed coreshell structure was confirmed by TEM observation.Results revealed that a sharp decrease in particle size was observed within the first 20 min of the polymerization,and the particle size remained quite constant afterwards.Monomer conversion reached about 70% within 30 min of the initiation,followed by a very slow increase to about 73% up to 3 h of polymerization.Optimization of the polymerization process demonstrated that,to achieve high MMA conversion,high PMMA grafting on CA and relatively narrow size distribution for the core-shell particles,polymerization temperature should be kept between 70℃ and 80℃,TBHP level at 0.18% to 0.36% of CA mass,MMA/CA ratios at 4/1 by mass and total content of MMA and CA not higher than 10% by weight in the system.Under these conditions,core-shell particles of PMMA-CA with MMA conversion 75% and PMMA grafting on CA 75% were achieved.The results were interpreted based on the mechanism of the initiation and particle formation.关键词：Casein;Methyl methacrylate;Redox initiation;Grafting polymerization;Core/shell nanoparticles
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发布时间：2021-03-19
Research Article
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