最新刊期
卷 ， 期 1 ， 2007
- 摘要：Polycarbosilanes (PCSs) were synthesized at high temperature under high pressure with polydimethylsilane (PDMS),liquid polysilane(LPS) and the soluble solid product from PDMS pyrolysis (LPCS),as raw materials,respectively.The PCSs synthesized at different temperatures from fifferent raw materials were characterized by IR,UV,NMR,and GPC,respectively.The structure evolution from raw material to PCS was found.On the other hand,the crude PCS was synthesized at 450℃ under high pressure with LPS.After dissolved and vacuum distilled at different temperature,fractions of PCSs with different molecular weights were obtained and characterized by IR.The synthesis mechanism of the PCS at high temperature under high pressure was proposed.The results showed that,during the synthesis process of PCS,Si—Si bonds were converted to Si—C bonds with the reaction temperature increasing,and the low molecular carbosilanes were therefore produced.The molecular weight of carbosilanes increased by dehydrogenation and dehydrocarbonation condensation between small carbosilane molecules,and then PCS was obtained.
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发布时间：2021-03-19 - 摘要：By ester coupling reaction with dicyclohexyl carbodiimide/N,N′-dimethyl amino pyridine as the active carboxyl group reagents,a linear azo polymer was constructed.It combines the unique biocompatibility and hydrophilicity of PEO with the biodegradability and low toxicity of 5,5′-azodisalicylic acid (Olsalazine,OLZ) used in the management of ulcerative colitis.The resultant condensation polymers were characterized by FTIR,NMR,GPC and DSC methods.It was found that changing the molecular weight of PEO blocks affected the loading ratio of OLZ and resulted in significant differences in the hydration and degradability of the condensation polymers.The therapeutically active mesalamine (5-aminosalicylic acid,5-ASA) was released from the aqueous PEO-OLZ condensation polymer solution with cecum contents through azo-reduction and hydrolysis.The resultant azo-containing condensation polymer with azo bonds in the main chain can either be used as a polymeric prodrug for 5-ASA or as a colon specific drug delivery carrier for other bioactive substances.
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发布时间：2021-03-19 - 摘要：A new fluorine-containing diamine of 2-trifluoromethyl-4,4′-diaminodiphenyl ether (3FODA) which has good solubility and high reactivity was synthesized.Two calculated molecular weight PMR polyimide resins were synthesized with 3FODA instead of methylene dianiline (MDA) in the first generation PMR polyimide KH-304 and PMR-15.The results showed that the monomer resin solution has high concentration,low viscosity and good stability under room temperature.
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发布时间：2021-03-19 - 摘要：A hyperbranched azo polyurethane was synthesized by an A2type monomer MDI and a B3 type monomer-4-(N,N′-bis(2-hydroxyethyl))amino-2′-hydroxyethoxyl-4′-nitrylazobenzene.The azo polymer was characterized by1H-NMR,UV-Vis spectrum and thermal analysis. The λmax of the polymer in DMF solution was determined to be 488 nm.The number average molecular weight determined by GPC is Mn =9300 with a polydispersion index 1.9.The glass transition temperature (Tg) of the polymer is 131℃ determined from DSC thermogram.The results showed the azo polyurethane has been successfully synthesized through this scheme.Surface-relief-gratings (SRGs) were observed on the polymer film after irradiated by an interference pattern of Ar+ laser beam for 1000 s.The surface modulation depth and the grating spacing were measured by AMF to be 67 nm and 770 nm,respectively.
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发布时间：2021-03-19 - 摘要：Inverse emulsion copolymerization of sodium acrylate (NaAA),acrylamide (AM),and acryloyloxyethyl trimethylammonium chloride (DAC)was investigated,using Span80-Tween80 as complex emulsifier and 2,2′-azobis-(2-amidinopropen)-dihydrochloride (AIBA) as initiator.The effects of polymerization temperature,initiator dosage,monomer concentration and composition of both DAC and AM,emulsifier content and HLB value,oil/water ratio,aqueous pH value on the polymerization conversion and the polymer intrinsic viscosity were studied.During the preparation process of the amphoteric polyacrylamide,the gel effect was evident from the increase of polymer intrinsic viscosity with increasing initiator dosage and comonomer concentration.The latex particle size of the amphoteric polyacrylamide emulsion was observed with a scanning electron microscope,and the structure of the amphoteric polyacrylamide was identified by FTIR spectroscopy.
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发布时间：2021-03-19 - 摘要：A series of ABS graft copolymers and SAN copolymers with different acrylonitrile (AN) contents were synthesized with emulsion copolymerization technique.By melt blending these copolymers with PVC resin and di-isooctyl phthalate (DOP),PVC/ABS,PVC/SAN,PVC/ABS/DOP and PVC/SAN/DOP blends were prepared.The miscibility and morphology of the blends were investigated by using dynamic mechanical analysis (DMA), TEM and SEM.It is found that in all cases PVC and ABS are immiscible for SAN copolymer with different AN contents.When AN content is less than 23.4% in SAN copolymers,a single tanδ peak over room temperature in DMA detection is found because of the introduction of DOP in the PCV/ABS blends,but the morphological observations show that the PVC and SAN copolymer are immiscible and the phase domain size of the blends intensively depends on the AN content of SAN copolymers in ABS graft copolymers.When the AN content of SAN copolymer is 23.4%,the size of phase domain in the blends is the smallest.
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发布时间：2021-03-19 - 摘要：By the emulsion polymerization process,organic polymers carrying functional groups have been involved in the elaboration of the hybrid latex in order to imporve the chemical bonding between the organic and inorganic components.The organic-inorganic hybrid nanoparticles have been synthesized using 3-trimethoxysilyl propyl methacrylate (MPS) by this method in our previous work.In the emulsion polymerization process of MPS and styrene,the partition of MPS in each phase of the emulsion not only influenced the free radical polymerization rate and the chemical composition of the copolymer,but also influenced the hydrolysis_condensation ractions of SiOR groups in MPS. The emulsion stability and the organic_inorganic hybrid microstructures largely depended on it also.In this paper,the MPS partition behavior is characterized by gas chromatography (GC),and the partition coefficients are also measured.It is found that the system becomes saturated when the MPS amount is about 11 wt% of polymer seeds,and most MPS are parted in the polymer phase.Through theoretical analysis and experimental approving,it was found that the MPS partition behavior didn't change with the particle size and chemical composition of polymer seeds,and the saturated concentrations of MPS in each phase were increased with the temperature.
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发布时间：2021-03-19 - 摘要：A new lithography technology called thin layer soft lithography (TLSL) was proposed for the improvements of soft lithography.In this article,PMMA uniform thin layer was first deposited on glass substrate using dip-coating technology with 30 mm/h immersion and withdrawn velocity.When a micropatterned PDMS stamp is placed on the PMMA thin layer surface with 20 g contact load and heated above the PMMA glass-transition temperature (Tg),PMMA melt will fill into the cavity between the stamp and the PMMA thin layer within 60 min time,thereby generating a negative replica of the stamp.SEM and optical micrograph images show that the PMMA micropatterns are separated from each other,which is very hard to obtain in normal micromolding or nanoimprint lithography.Hence this technology is the combination of the advantages of room temperature nanoimprint lithography with the capillary force lithography.It overcomes the use of extremely high pressure in room temperature nanoimprint lithography and the lack of the drive force in capillary force lithography.
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发布时间：2021-03-19 - 摘要：Poly(ε-caprolactone) (PCL) was chemically crosslinked with various amounts of benzoyl peroxide (BPO).The effect of BPO contents,crosslinking temperature and time on the crosslinking reaction was studied.The thermal,mechanical,and biodegradable properties of crosslinked PCL were also examined by DSC and DMA etc.The results showed that the melting temperature,crystallinity and glass transition temperature decreased with increase in BPO contents,while the crystallization temperature increased with increase in BPO content.The Young's modulus and elongation at break generally decreased with increase in BPO content.Moreover,the crosslinked PCL still had biodegradable ability.
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发布时间：2021-03-19 - 摘要：An approach,mild mixing,has been demonstrated for the preparation of polymer/CaCO3 nanoparticle composite in twin-screw extruder.In this method,the pre-dispersed nanoparticle suspensions were blended with melting polymers,PP,PE,PC and PBT,in a weak shearing field using an extruder,followed by removing the water from vent.The four typical polymeric nanocomposites were prepared by mild mixing.The dispersion quality of nano-CaCO3 in the matrix of polymer was characterized by scanning electron microscopy (SEM),and the nano-CaCO3 was found to be dispersed in polymer matrix at the nanoscale.The molecular weights of PC and its nanocmposite showed that degradation did not occurr in the process.The mechanical properties of composites had increased slightly with the content of 1.5 wt％ nano-CaCO3. It proved that the approach was suitable for the preparation with polar and non- polar polymers.
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发布时间：2021-03-19 - 摘要：A nickel (Ⅱ) catalyst of diphosphinoamine complex ［N,N-bis(diphenylphosphino)-p-methoxyaniline nickel(Ⅱ) dichloride］was synthesized.Norbornene polymerization catalyzed by this nickel(Ⅱ) complex (PNP-Ni)/MAO system was investigated.The influence of reaction parameters (temperature,Al/Ni mole ratio,and catalyst concentration) on polymerization of norbornene was evaluated.Results showed that the catalytic system displayed high catalytic efficiency with 105g PNBE/(mol Ni) magnitude order.The Mw of polynorbornene is higher than 1×106g·mol-1 and the MWD is narrow（Mw/Mn＜2）.Also,the PNBE is of excellent heat-resistant property and the Tg is higher than 300℃,and it is soluble in cyclohexane,chlorobenzene,and so on.According to 1H and 13C-NMR spectra,the polymerization mechanism is vinyl-addition type polymerization,and the contents of stereo-triad of PNBE are (mm)= 53％,(mr)=39%,(rr)=8%.
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发布时间：2021-03-19 - 摘要：Spherical hydrophilic magnetic polymer (MGM) containing oxiranes was synthesized by designing the inverse suspension polymerization system in which formamide was employed as the dispersant of magnetic Fe3O4 microcrystal.Scanning electron microscopy (SEM),FT-IR spectroscopy,X-ray diffraction (XRD),vibrating sample magnetometer (VSM),low temperature N2 adsorption and chemical analysis methods were used to characterize the properties of the polymer.The results showed that MGM had good spherical shape and narrow size distribution,and the particles with diameters ranging from 0.13 mm to 0.28 mm were about 91 wt%.The surface hydrophilicity of Fe3O4 microcrystal was improved by formamide dispersing treatment.The gel particles made by the copolymerization of glycidyl methacrylate and N,N′-methylene bisacrylamide could encapsule Fe3O4 microcrystal to produce colloid cores,and uniform and stable MGM microspheres were formed by the conglomeration of the colloid cores.The saturated magnetization of MGM reached 6.5 emu/g while the Fe3O4 content were 6.17%.The specific surface area,average pore diameter and pore volume and oxirane content was 117.6 m2/g,15.6 nm,0.46 cm3/g and 0.53mmol/g,respectively.Penicillin G acylase (PGA) was immobilized on MGM microspheres by the covalent coupling between the reactive oxiranes of MGM and amino groups of PGA under mild conditions.The apparent activity of the immobilized PGA reached 502 IU/g for hydrolyzing penicillin G potassium to 6-aminopenicillanic acid at 37℃.There was no agglomeration of the magnetic particles in applications .
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发布时间：2021-03-19 - 摘要：The organic montmorillonite VC18-MMT was prepared by the exchanging inorganic cations with vinylbenzyldimethyloctadecylammionun chloride (VOAC) which could be co-polymerized with styrene.The predispersion of VC18-MMT was realized via sonicating the suspension of the montmorillonite particles in emulsifier solution,and then the styrene was added into the system and the in situ emulsion polymerization was carried out to prepare PS/VC18-MMT nanocomposites.The structure of final nanocomposites was characterized by XRD and TEM.The results indicated that the most of montmorillonite was fully exfoliated into individual layers and uniformly dispersed in the polystyrene matrix.The dynamic mechanical properties of the nanocomposites were determined by DMA,which demonstrated that the storage modulus and glass transition temperature of polystyrene were increased by compositing of montmorillonite.The polymer grafted on the layers of montmorillonite could be obtained by ion exchanging with lithium cations.The structure and average molecular weight of the polymer were characterized by NMR and GPC.The results showed that the polymer grafted on layers of montmorillonite was identifed as the copolymer of styrene with VOAC and the average molecular weight of the copolymer was lower than that of free polystyrene.One copolymer chain averagely comprised about 25 VOAC molecules,which can be calculated through the concentration of VOAC and the mass of copolymer in the galleries of montmorillonite.
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发布时间：2021-03-19 - 摘要：Scanning electron microscopy (SEM),X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy in attenuated total internal reflectance mode (FTIR-ATR) were employed to probe the surface chemical and physical structure natures of the surface modified wool.The SEM analysis shows the nano-size roughness on the plasma treated or chemical surface modified wool scales.Wenzel equation and Cassie and Baxter equation are used to illustrate the relationship between surface roughness and contact angle,then to reveal the reasons why surface modifications are able to impart an improved water repellence and oil repellence and stain resistance to wool.The XPS and FTIR-ATR analyses indicate the surface disulfide bonds scission and surface lipid modification/removal on the surface modified wool.The wool surface chemical changes are beneficial for water/oil repellent agent to absorb and fix on wool fibers.The synergistic effect between surface modification and water/oil repellent finishing imparts a lotus-like effect to wool,resulting in super water repellence and oil repellence functions of wool.
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发布时间：2021-03-19
Research Article
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- 摘要：A novel poly(bis(2-methoxyethoxy)phosphazene)graftpoly(ε-caprolactone) copolymer (PMEP-g-PCL) was synthesized and characterized to meet the various demands for biomedical materials.The major advantage of such a copolymer is to reduce the acidity of degradation products,since the basic degradation products of polyphosphazene backbone can neutralize the acidic degradation products of polyester to a certain degree.The copolymer was prepared via ringopening polymerization of ε-caprolactone by using Sn(Ⅱ)2-ethylhexanoate (SnOct2) as catalyst and the hydroxyls in polyphosphazene as initiators.Hydroxy groupfunctionalized polyphosphazenes were obtained in three steps.First,poly［bis(2-methoxyethoxy)phosphazene was synthesized and then its methoxy end groups were partially cleaved by reaction with trimethlsilyl iodide (ISi(CH3)3) to give silylated polymers.At last,the silylated polymers were hydrolyzed to yield polyphosphazenes containing hydroxyl side groups.The amount of hydroxyls along the polyphosphazene backbone could be adjusted by changing the feeding dose of ISi(CH3)3,and polymers with different grafting ratio of —OH had been prepared.However,a significant drawback of this functionalization reaction was that ISi(CH3)3 could induce polymeric backbone cleavage，and molecular weight of polyphosphazene decreased rapidly with increasing the amount of ISi(CH3)3.Besides,the conversion of ISi(CH3)3 was relatively low due to side reactions such as oxidation and hydrolysis.Efforts had been put to improve the reaction via minimizing unwanted reactions.PMEP-g-PCL copolymers with different grafting ratios and lengths of polycaprolactone side chains could be synthesized by using polyphosphazenes bearing various amount of hydroxyls as backbone,as well as by adjusting the feeding dose of ε-caprolactone monomers.The structure of PMEP-g-PCL copolymers was investigated and confirmed by intrinsic viscosity,1H-NMR,FT-IR and DSC analyses.Especially,the DSC measurements demonstrated that the PCL side chains of PMEP-g-PCL possessed lower melting point and crystallinity than the linear PCL with similar molecular weight,for the fact that entanglement is more liable to take place among polymer chains grafted to polyphoaphazene backbone than those in homogeneous PCL homopolymers.And adversely it was strongly suggested that a kind of copolymer with the expected structure,that PCL short chains were attached to polyphosphazene,had been successfully synthesized.These PMEP-g-PCL copolymers could have different degradation behaviors and might serve as potential biomedical materials for the applications in tissue engineering and controlled drug delivery.
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发布时间：2021-03-19 -
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