最新刊期
卷 ， 期 1 ， 2012
- 摘要：To solve biofouling problems,different antifouling paints have been designed,developed and practically applied.Here we briefly introduce the nature and process of biofouling; review several currently used common strategies in the development of different biocidal antifouling coatings; illustrate how we are able to combine a number of existing approaches into some integrated novel designs; and finally report some of our recent RD progresses in direction.关键词：Marine biofouling;Antifouling polymer materials;Self-polishing coatings;Microgels;Dynamic surface
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发布时间：2021-03-19
Reviews
- 摘要：The effects of the amount of chain extender,2,2'-(1,3-phenylene)bis(2-oxazoline) (1,3-PBO),on the synthesis of lactic acid based poly(ester-amide) (PEA) were studied.The carboxyl-terminated lactic acid-succinic anhydride copolymer (P(LA/SA)) was synthesized via directly melt polycondensation of L,D-lactic acid with succinic anhydride and Sn(Ⅱ)octoate as the catalyst at 168℃ and 0.098 MPa by the method of a gradient increased temperature.Then,the PEA was synthesized with P(LA/SA) as prepolymer and 1,3-PBO as extender.High molecular weight polymer was produced within a narrow range of copolymerization parameters.The highest molecular weights were achieved with the molar ratio of oxazoline/carboxyl end groups being 1.0/1.4 at 150℃ and 0.098 MPa for 15 min.The structure were characterized by spectroscopy (FTIR and 1H-NMR) and the properties were investigated by gel permeation chromatography (GPC),differertial scanning calorimetry (DSC),X-ray Diffraction (XRD),thermogravimetric analysis (TGA) and scanning electron microscope (SEM).Results indicated that the highest molecular weight was over 36104 measured by GPC and the chain stiffness presented a tendency upward detected in mechanical properties as a result of the introduction of benzene rings and amide groups into PLA/SA.A distinct improvement in the thermal stability of the resulting polymer with the chain extender was observed compared with the unmodified PLA by TG,just as an one-step thermal decomposition.The crystallinity of the resulting polymer was higher than that of P(LA/SA),but lower than that of PLA which indicated that the flexibility of the resulting polymer was superior to P(LA/SA).
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发布时间：2021-03-19
Rapid Communications
- 摘要：The surfactant-free emulsion polymerization (SFEP) of styrene and methyl methacrylate carried out in the aqueous solution of poly(ethylene glycol)(PEG) was studied.With high power optical microscope,Coulter counter and transmission electron microscopy,particle size,particle size distribution and zeta potential were measured in the process of polymerization.It is interesting to observe that the polymer particle size experiences a process from small to large,which can be more than 1000 m,and then from large to small,which is back to a range of 0.04 ~ 0.18 m.When the particle size returns to nanometer scale,the system has an obvious temperature rising.This phenomenon is different from the traditional nucleation mechanism of SFEP.The particle,which is formed by the homogeneous nucleation or oligomer micelle nucleation mechanism that is popularly received as traditional nucleation mechanism of SFEP,usually has a trend to become bigger and bigger to the end in the process of SFEP.It is obviously found that the freshly formed particles are first coalesced to form a particle pile,which is bigger than 1000 m and even seen with eyes,and then corrupted into tinny ones,which are smaller than 0.04 m and even beyond the ability of high power optical microscope.With transmission electron microscopy (TEM),it was clearly proven the existence of paricle pile which was composed of a lot of little particles ranging from 40 nm to 80 nm.And by use of Coulter zeta potential measurement,it was found that the zeta potential of particles had a trend from low to high level,and experenced abruptly increase in zeta potential at 60 min which was just the time that the little particle seperated from the paricle pile.This phenomenan was very different from the system that SEFP was carryed out in water without PEG,in which the zeta potential of particle was keeping about -50 mV and just changed a little after 50 min.It was reasonble to think that the potential increase was the driving force to make the little particles to escape from the particle pile.Therefore,the mechanism of coalescence-separate nucleation is proposed.关键词：Poly(ethylene glycol);Surfactant-free emulsion polymerization;Particle size and its distribution
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发布时间：2021-03-19 - 摘要：The cure kinetics of N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane (TGDDM) and 4,4'-diaminodiphenylsulphone (DDS) nanocomposites filled with graphite oxide (GO) was studied by isothermal differential scanning calorimetry (DSC).Furthermore,the functional groups on the surface of GO and their influence on the cure behaviors of TGDDM/DDS/GO nanocomposites were studied by X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR),and the thermal stabilities of the neat graphite and GO were compared by thermalgravitimetric analysis (TGA).The XPS,FT-IR and TGA results showed that there were large numbers of polar functional groups such as hydroxyl,carboxyl and cyclic epoxide groups on the surface of GO,which effected the cure behaviors of TGDDM/DDS/GO nanocomposites.The experimental data of the isothermal DSC for both the neat TGDDM/DDS system and its GO nanocomposites showed an autocatalytic behavior.Furthermore,with the increase of GO contents,the time to the maximum cure rate decreased whereas the initial cure rate increased with the increase of GO contents,which indicated that GO catalyzed the cure reaction of epoxy.The apparent activation energy for the initial stage of the reaction (E1) of TGDDM/DDS/GO nanocomposites obtained by Kamal's model decreased first and then increased with the increase of GO contents,while the apparent activation energy for the reaction after the initial autocatalytic stage (E2) slight decreased with the increase of GO contents.Good agreement between the experimental data and the autocatalytic model with the modified diffusion factor in the later stage of cure was found over the whole curing temperature range for all of the neat epoxy resin and its nanocomposites with GO.The results showed that the incorporation of GO accelerated the cure reaction of the TGDDM/DDS system at lower GO content due to the interaction between the functional groups on the surface of GO and the epoxy resin.关键词：Graphite oxides (GO);Epoxy resin;Nanocomposites;Cure kinetics
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发布时间：2021-03-19 - 摘要：Provided a method to synthesize Nylon-6 oligomers with certain molecular weight and to further synthesize polyesteramides having short Nylon-6 segments connected by ester linkages.Polyamide prepolymer (PrePA) with molecular weight of 524.6 to 808.1 was synthesized by a ring-opening polymerization of -caprolactam in the presence of aminoethanol under the catalysis of H3PO3.The chain extension of the PrePAs was studied using N,N'-carbonylbiscaprolactamat (CBC) and 2,2'-(1,4-phenylene)-bis(2-oxazoline)(PBOX) as combined chain extenders.Through polycondensation of PrePA with adipic acid,polyesteramide prepolymers(PrePEA) with intrinsic viscosity of 0.22~0.30 dL/g were synthesized.Chain extension of the PrePEAs was carried out using PBOX and CBC as combined chain extenders and the chain extended polyesteramide(ExtPEA) with intrinsic viscosity up to 0.74 dL/g was obtained.The ExtPEAs were characterized by FTIR and 1H-NMR spectra,differential scanning calorimetry(DSC),thermogravimetric analysis (TGA),wide angle X-ray scattering (WAXS) and tensile test.The DSC study showed that after chain extension the Tm and Hm of the polyesteramides decreased.ExtPEA with [] of 0.72 dL/g had the Tg of 30℃ and Tm of 163℃.WAXS characterization showed that the ExtPEA had similar crystal characteristics to the Nylon-6 crystallites.TGA study showed that the ExtPEA had good thermal stability with initial decomposition temperature over 330℃.Tensile test showed that typical ExtPEA samples had a tensile strength of 14.1 MPa and a strain at break of 68.6%.The ExtPEA has high Tm,good thermal stability and moderate tensile strength,and is suitable for melt processing.Meanwhile,presence of the ester linkages and lower crystallinity in the ExtPEA may lead to improved biodegradability of the ExtPEA compared to the normal nylon-6.关键词：Aliphatic polyesteramide;Chain extension;Caprolactam;Aminoethanol;Adipic acid
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发布时间：2021-03-19 - 摘要：Polymer dispersed liquid crystals (PDLCs) were prepared by UV photopolymerization of the mixture monomers of 2-ethylhexyl acrylate (EHA),ethylene dimethacrylate (EDMA) and pentaerythritol tetraacrylate (PETTA) in the presence of liquid crystals P0616A and photoinitiator Irgacure 184.The effects of different alcohols with different short chains, i.e .,ethanol (EtOH),n-butanol (nBA),n-hexanol (nHA),n-octanol (nOA) and n-tetradecanol (nTA),on the photopolymerization kinetics,liquid crystal phase transition temperature (TNI) and electro-optical performance of PDLCs were investigated.The results reveal that the addition of these non-reactive low molecular alcohols,especially nBA,significantly increases the polymerization rate and monomer conversion of monomer/liquid crystal dispersions,and the monomer conversion reduces with increasing the chain length of the alcohol,but remains higher than that without alcohol.Additionally,TNIof PDLCs decreases with adding alcohols,and tends to further decrease with the increasing of alcohol chain length.The addition of alcohols also increases the fraction of nematic phases in PDLCs,and the fractions of nematic phases in PDLCs containing nBA and nTA are lower than those containing EtOH,nHA and nOA.Finally,the alcohols dramatically decrease the threshold voltage,saturated voltage and contrast ratio of PDLCs.Combining the effect on the photopolymerization kinetics,nBA is the best choice for improving the performance of PDLCs.关键词：Polymer dispersed liquid crystals;Alcohol;Photopolymerization kinetics;Phase transition;Electro-optical performance
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发布时间：2021-03-19 - 摘要：4-Vinyl pyridine (4VP) was grafted on micron-sized silica gel particles in a manner of graft from in a solution poltmerization system by right of the mediation of the coupling agent 3-methacryloxypropyltrimethoxysilane (MPS),obtaining the grafted functional particles P4VP/SiO2.Subsequently,the molecular imprinting towards the grafted P4VP was conducted with L-Asp that is one enantiomer of aspartic acid (Asp) as template molecule and 1,6-dibromohexane as crosslinking agent by using the novel surface-molecular imprinting technique put forward and established by our research group,and the L-Asp molecule-imprinted material MIP-P4VP/SiO2 was prepared.With another enantiomer of aspartic acid,D-Asp,as a contrast compound,both static method and dynamic method were adopted to study the recognition character of MIP-P4VP/SiO2 for L-Asp,and the separation ability of MIP-P4VP/SiO2 towards L-Asp and D-Asp in the raceme was explored.The experiment results show that MIP-P4VP/SiO2 have obvious recognition selectivity and fine binding affinity for L-Asp,and the selectivity coefficient is equal to 3.85 with respect to D-Asp,displaying the fine separation property for the enantiomers of aspartic acid.Besides,MIP-P4VP/SiO2 has excellent elution property,with a diluted aqueous solution of NaOH as the eluent,the desorption ratios of L-Asp reach 98.52% in 12 BV.关键词：Aspartic acid;Enantiomer separation;Surface-molecular imprinting;4-Vinyl pyridine;Graft polymerization;Molecular recognition
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发布时间：2021-03-19 - 摘要：Towards the low-cost fabrication of a hard imprinting mold with micro-and nanostructures,a novel photocurable inorganic polymer was modified from perhydropolysilazane (PHPS) by grafting with 2-isocyanatoethyl methacrylate (ICMA) in this paper.The as-modified product was characterized by the methods of FTIR,1H-NMR,13C-NMR and 2D-1H-1H-NMR (COSY).The new peaks at =3.2~3.8 on1H-NMR spectra of the product were assigned to be the NHCH2 group,and =152~158 on 13C-NMR spectra was assigned to be the CONH group.In the FTIR spectra,the absorbing peaks at 2153 and 1363 cm-1(N=C=O),1117 cm-1(CN C) of PHPS were obviously consumed after chemical modification,and the new peaks at 1690, 1530 and 1314 cm-1(CONH)were appeared.Combined with the COSY analysis,it was concluded that the UV sensitive methacrylyate group was successfully grafted to PHPS,and methacrylated perhydropolysilazane (MPHPS) was used to name the as-modified product here.MPHPS was then used to fabricate the micro-and nanostructures via UV imprinting lithography using a fluoropolymer (FP) mold with microstructures,adding a pressure ranged in 0.1~0.4 MPa.The efficiency of the pattern transfer from FP mold was increased by the pressure increasing,and the thoroughly pattern copy was realized at 0.23 MPa.Besides,nanostructures with 90 nm,70 nm feature sizes were obtained at the pressure of 0.4 MPa.Then the as-prepared micro-and nanostructures were converted into SiO inorganic phase by a followed hydrolysis treatment.The converted product was concluded to be a composition of SiO1.5 from XPS depth profile.The final obtained mold was optical transparent,and with a hardness of 4.5103 MPa and a elastic modulus of 115103 MPa.关键词：Perhydropolysilazane;Photocurable;Hydrolysis;Micro-and nanostructures;Imprinting mold
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发布时间：2021-03-19 - 摘要：Polycarbonate is synthesized by melt transesterification of diphenyl carbonate (DPC) with bisphenol A (BPA).The catalytic activity of metal acetylacetonates and the effects of the stronger or weaker bond between the catalyst and the reactant,catalyst concentration,initial monomer molar ratio,initial pressure and temprature are investigated.The logarithms of the stability constants (lg1) of dibenzoyl methane (DBM) complexes of the corresponding metal species are regarded as corresponding to the bond strength between metal species (catalyst) and benzoyl group (reactant),which are correlated by double volcanoes-shaped relationship with the intrinsic viscosity ([]) of the PC produed with the corresponding metal acetylacetonates as catalysts.Consequently,the catalytic activity of the metal compounds is affected by the basic of acetylacetonate anion and the chelating capacity of each metal species,which is found to be very useful in forecasting the catalytic activity of the metal compound.In all the catalysts,lithium acetyacetonate (LiACAC) is the best one,by which the sample catalyzed has the lowest fries level and polydispersity index (PDI= 2.12),besides its colorless and high molecular weight ([]= 0.710 dLg-1) .Our study exhibites that the best reagent molar ratio:nBPA∶nDPC∶nLiACAC= 1.0∶1.08∶1.510-4,the optimal initial pressure in the transesterification stage:4000 Pa and the optimal melt polymerization temperature 260℃.关键词：Polycarbonate;Melt transesterification;Lithium acetyacetonate;Fries arrangement
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发布时间：2021-03-19 - 摘要：A new acid absorbent of calcium hydride was used in the synthesis of high molecular weight poly(p-phenylene terephthalamide) (PPTA) and compared with the traditional acid absorbent of pyridine.Pyridine utilized as acid absorbent in terephthaloyl chloride and p-phenylenediamine condensation polymerization is helpful to get high molecular weight product,however,it is difficult to separate pyridine with other agents in further agent recycling process,which is unacceptable in PPTA industrial production.This work investigates the effect of calcium hydride replacing pyridine as acid absorbent on the PPTA synthesis process and the chemical structure of resulted PPTA.Multiple instrumental measurements such as element analysis,Fourier transform infrared spectrometry(FTIR),X-ray diffraction(XRD) and thermogravimetric analysis (TGA) were carried out in the characterization of the yielded products.Inherent viscosity data showed that high molecular weight PPTA could be obtained with calcium hydride as acid absorbent.On the other hand,there existed an optimum addition amount of calcium hydride at which high molecular weight PPTA with inherent viscosity high over 6.5 could be obtained.Element analysis,infrared spectroscopy and XRD gave that no difference in element content,molecular structure and crystal structure could be recognized from the products using the two acid absorbents.TGA curves showed that the products using both acid absorbents degraded at approximately 550℃.All the results demonstrate it is feasible to synthesize high molecular weight PPTA using calcium hydride as acid absorbent in large scale production of PPTA.关键词：Calcium hydride;Poly(p-phenylene terephthalamide);Acid absorbent
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发布时间：2021-03-19 - 摘要：The copolymer of -methyl styrene (AMS) and maleic anhydride (MANH) was synthesized by self-stable precipitation polymerization.The resulting AMS-MANH copolymer was saponified and then served as macroinitiator and emulsifier for the further surfactant-free polymerization of methyl methacrylate (MMA).Surfactant-free emulsion polymerization of MMA was carried at 90℃.The AMS-MANH copolymer and the obtained block-copolymer were characterized by Fourier transform infrared spectroscopy (FTIR),nuclear magnetic resonance (NMR),gel permeation chromatography (GPC) and scanning electron microscopy (SEM).The results showed that the surfactant-free polymerization of MMA can be carried out by using saponified AMS-MANH copolymer,without any other initiator and emulsifier.Based on FTIR and 1H-NMR,the emulsion polymerization product was block copolymer of PMMA and AMS-MANH copolymer.During the process of surfactant-free polymerization of MMA,the polymerization rate increased along with the increasing of the concentration of macroinitiator.The maximum of polymerization conversion was 85% and the particle sizes ranged from 150 nm to 200 nm.The intrinsic viscosity number of the copolymer was about 80 mL/g.In addition,the intrinsic viscosity numbers of copolymers increased linearly with the rising of polymerization conversion.Based on the research results,a possible reaction mechanism has been proposed.This novel method is expected to be applied to other kinds of monomers.关键词：-Methyl styrene;Macroinitiator;Emulsion polymerization;Methyl methacrylate
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发布时间：2021-03-19 - 摘要：The polylactide/attapulgite nanocomposites (PLA-Att composites) were prepared by melt mixing.The elongation at break and the tensile strength of PLA-Att composites increased first with increasing Att content and then decreased when Att content exceeded 10 wt%.The SEM results showed that the Att nanorods were well dispersed in PLA matrix.The DSC curves during the cooling and the second heating run showed that Att can enhance the crystallization rate of PLA.Furthermore,the rheological behaviors were investigated.When the content of Att was larger than 8 wt%,the storage modulus curve of PLA nanocomposites demonstrated a plateau region at the low frequency range,indicating the formation of a network structure in the composite,where the Att nanorods acted as the physical entanglement points to increase the relaxation time of the PLA-Att composites.FTIR spectrum of the extracted Att fillers from the nanocomposites showed that Att had strong interaction with PLA.PLA chains could be adsorbed at the surface of Att nanorods,reducing the thickness of the matrix layer.We suggest that the addition of Att nanorods changes the strained condition of the samples from the 3-dimensional stress to the 2-dimensional plane strain state and the maximum shear stress could reach the yield strength of PLA matrix so as to induce brittle-ductile transition of the sample.关键词：PLA;Attapulgite;Nanocomposites;Rheological property;Relaxation time;Mechanical property;Elongation at break
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发布时间：2021-03-19 - 摘要：A three armed ATRP initiator (C-Br3) containing photo-sensitive coumarin group was designed and synthesized in a multi-step reation,which was used to prepare amphiphilic photo-sensitive star polymer C-(PDMAEMA)3 by ATRP with 2-(dimethylamino)ethyl methacrylate (DMAEMA) as hydrophilic monomer and CuBr/PMDETA as the catalytic system.The structures of C-Br3 and C-(PDMAEMA)3 were confirmed by FTIR,GPC and1H-NMR.It was found that the star polymer could form polymer micelles in aqueous solutions.And the coumarin center group of the star polymer can be reversibly photo-dimerized upon 365 and 254 nm irradiation.However,the hydrodynamic size analysis determined by Malvern Zetasizer Nano-ZS showed that the polymer micelles had a gaussian distribution (87.7 27.8) nm of size before photo-crosslinking,and it changed slightly upon 365 and 254 nm irradiations.The reason for this slight size changes maybe that there were very minor changes in the polymeric amphiphilic structure before and after photo-reactions.关键词：Star polymer;Coumarin;Reversibility;Photo-dimerization;Micelles
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发布时间：2021-03-19
Research Article
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