最新刊期
卷 ， 期 3 ， 2009
- 摘要：On-line tracking of reaction-induced phase separation has been realized for the first time by using high frequency ultrasonic wave,which is based on the Rayleigh scattering of ultrasonic wave on the interface of a multiphasic system.The new technology was employed to track the curing reaction of epoxy resin in PEG medium.The investigation involved the effects of concentration,reaction medium,amount of curing agent and temperature on the reaction-induced phase separation.Based on an intensive analysis of spinodal demixing (SD) in this curing system,a physical model has been put forward,in which two processes have been abstracted to describe the reaction-induced phase separation.One is the process of phase separation,and the other is phase isolation.In the related mathematical model the scattering intensity of ultrasonic wave is expressed as a function of the rates of both phase separation and phase isolation,by which the experimental data from ultasonic tracking have been explained reasonably.The online tracking technology found that under high concentration or by raising the reaction temperature the phase separation would be suppressed by polymerization to yield phase structures with high connectivity.In PEG2000 medium and under high concentration a hysteresis effect of function l（t） was found and the SD mechanism was supported.The phase separation is also influenced by the weight ratio of epoxy resin and curing agent,a ratio of 4/1 was proved to suitable for the completion of both phase separation and polymerization.The new technology made it possible to realize a realtime analysis of the changing of multiphasic structure during the phase separation,which might provide an experimental basis for the control of phase separation.
- 11
- |
- 12
- |
- 0
发布时间：2021-03-19 - 摘要：In order to overcome the defects of poly(p-dioxanone)(PPDO) due to its hydrophobicity,amphiphilic PPDO/poly(ethylene glycol)(PEG) multiblock copolymers were synthesized by coupling the dihydroxylterminated PPDO with dicarboxylic acidterminated PEG.The structures and molecular characteristics of the resulting PPDO/PEG multiblock copolymers were studied by 1H-NMR and GPC.The crystallization and thermal stability of the copolymers were studied using DSC and TGA.DSC analysis showed that the PPDO blocks restrained the crystallization of PEG blocks.TGA showed that the multiblock copolymers underwent thermal degradation in two separate steps for the PPDO and PEG blocks, respectively from which the PPDO contents could be calculated, and the results were very close to the theoretical values.Polymeric nanoparticles were prepared in an aqueous medium by dialysis technique.The more the content of hydrophilic PEG in copolymers,the easier the formation of nanoparticles.Dynamic light scattering (DLS) was used to investigate the nanoparticles of copolymers,showing a mono-dispersed size distribution and hydrodynamic diameters of around 173～193 nm .The novel PPDO/PEG multiblock copolymers may have a potential application in drug delivery systems.
- 26
- |
- 11
- |
- 5
发布时间：2021-03-19 - 摘要：The electrochemical polymerizations of a series of ortho-disubstituted benzenes were investigated by experimental and theoretical approaches. The results indicated that o-dihydroxybenzene (oHDB),o-dimethoxybenzene (oDMOB) and 1-hydroxy-2-methoxybenzene (HMOB) in pure boron trifluoride diethyl etherate (BFEE) can be succefully electropolymerized. The 1H,13C-NMR spectra of these monomers and their corresponding polymers proved that the polymerization occurred mainly at C4 and C5 positions. However the others such as o-xylene,1,2benzenedithiol,1,2-dibromobenzene,1,2-dichlorobenzene,1,2-dicyanobenzene and 1,2-dinitrobenzene can not be electropolymerized under similar conditions. These intrinsic characteristics have been revealed by the experimental investigation on these o-disubstituted benzenes together with the theoretical calculations. The cyclic voltammetry and linear sweep voltammetry were used to determine oxidation potential onset of the monomers. Optimizing the ground-state geometries of the monomer and the radical cation of HOMO,LUMO and electron spin density were calculated by using the density functional theory (DFT) at the B3LYP/631G(d,p) level. From the experimental point of view,the oxidation potential onset of the monomer is not the control factor for the electropolymerization. According to theoretical studies,the monomers substituted by electrondonating groups have more negative electronics than the monomers substituted by electron-withdrawing groups. These monomerso-DHB,oDMOB and HMOB with negative electronic charges of (C4,C5) ca. -0.093～-0.103 can be electropolymerized in BFEE. The others with the electronic changes of (C4,C5) ca. -0.078～-0.085 cannot be electropolymerized in the same media. Therefore,we can extrapolate that the negative electronic of reaction site maybe has a critical value (probobly≈|0.09|),which is one of the condition for electropolymerization of the monomer. From the frontier molecule orbitals theory,the reactions between the active molecules mainly happens on the highest frontier electron density involving the two frontier orbitals having the smallest energy gap and obey orbital symmetry rules. Therefore,the orbital symmetry of HOMO and LUMO of the polymerization site should be matching. oHDB, oDMOB,and HMOB via α-HOMO and β-LUMO interaction having the smallest energy gap are satisfied with symmetry rules,they can be electrochemically polymerized. Whereas the others such as o-xylene,1,2-dibromobenzene,1,2-dichlorobenzene,1,2-dicyanobenzene and 1,2-dinitrobenzene via β-HOMO and α-LUMO interaction having the smallest energy were antisymmetrical,which cannot be electropolymerized. Therefore,the HOMO-LUMO orbital symmetry matching is another condition for the electrochemical polymerization of o-disubstituted benzenes.
- 19
- |
- 12
- |
- 2
发布时间：2021-03-19 - 摘要：Ionic liquid comonomer 1-allyl-3-methylimidazolium chloride (［AMIM］Cl) was first used to copolymerize with acrylonitrile(AN) successfully in various conditions.This was achieved by using azobisisobutyronitrile as the initiator and dimethyl sulfoxide as the solvent.The kinetics of the above copolymerization was studied.The values of monomer apparent reactivity ratios were calculated.The apparent reactivity ratios of AN and ［AMIM］Cl are as follows:rAN=8.11,rAMIM］Cl=0.The copolymers were obtained with high molecular weights and high hydrophilicity.［AMIM］Cl has dual functions in the dope:the part in the molecular chains can mediate the hydrophilicity and spinnicity of the copolymers,and the other part in the solution can decrease the viscosity of the dope.The copolymers were characterized by 1H-NMR,GPC,DSC and TGA.The copolymers may be potentially useful in preparing precursor fibers and carbon fibers.
- 31
- |
- 12
- |
- 2
发布时间：2021-03-19 - 摘要：In order to combine the advantage of a biopolymer with clay in a drug delivery system,the simple solution-mixing processing technique was used to prepare carboxymethyl chitosan/organic rectorite nanocomposites(COR).The rectorite (REC) was modified with cetyltrimethyl ammonium bromide.A study on these nanocomposites’ microstructures and configurations was conducted through observation of X-ray diffraction (XRD)，fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM).The results indicated that carboxymethyl chitosan chains were inserted in silicate layers to form the intercalated nanocomposites,the interlayer distance of rectorite was magnified and rectorite dispersed well in carboxymethyl chitosan matrix.Bovin serum albumin(BSA),as a model protein drug,was incorporated into the nanocomposite/alginate microspheres.The results showed that their encapsulation efficiency and controlled release property were better than those of pure carboxymethyl chitosan/alginate microspheres.The encapsulation efficiency increased from 56% to 86%. In vitro release studies showed a burst effect and a slow and continuous release followed,and the release time prolonged from 24 h to 72 h.Drug release from nanocomposite/alginate microspheres was pH sensitive.The release rate was slow at pH 1.2 and rapid at pH 7.4,which can be used for drug delivery to the intestinal and colon.Therefore,the carboxymethyl chitosan/organic rectorite nanocomposites are of great potential in the biomedical field.
- 18
- |
- 11
- |
- 3
发布时间：2021-03-19 - 摘要：Biodegradable polyblends of poly(propylene carbonate)(PPC)/poly(butylene succinate) (PBS) and PPC/PBS/DAOP (diallyl phthalate) were prepared by melt blending.The miscibility,crystallization,thermal stability and mechanical properties of the polyblends were investigated by fourier transform infrared spectroscopy (FTIR),differential scanning calorimetry (DSC),thermogravimetric analysis (TGA),polarized optical microscope (POM) and tensile tests.The data from FTIR and DSC indicated that PPC and PBS were immiscible,PPC showed insignificant influence on the crystallinity of PBS,DAOP was a suitable plasticizer in the studied blending system.Compared with polyblends of PPC/PBS=30/70(W/W),Tg of the polyblends (PPC/PBS/DAOP=30/70/30(W/W)) decreased 36.9℃.The TGA results indicated that the thermal decomposition of PPC and PBS was independent on each other,but the thermal decomposition temperatures (Td-5%) of the PPC/PBS polyblends increased by 15～59℃ when the weight ratio of PBS increased from 10% to 90%.On the contrary,the addition of DAOP in PPC/PBS polyblends decreased the Td-5%.POM observation revealed that DAOP promoted the crystallization of PBS.The tensile curves showed that DAOP increased the ductility of the polyblends, compared with the polyblends of PPC/PBS=30/70(W/W),the elongation at break of the polyblends (PPC/PBS/DAOP=30/70/5(W/W)) increased by 31 times from 21.0% to 655.1%,and the corresponding break energy increased by 34 times from 0.1 J/mm2 to 3.4 J/mm2,which was very important for enlarging the application temperature window of the polyblends.
- 31
- |
- 18
- |
- 7
发布时间：2021-03-19 - 摘要：Ternary rare earth metal coordination catalysts prepared from Y(CCl3COO)3,glycerin,and ZnEt2 were confirmed to be effective for the copolymerization of carbon dioxide and various epoxides.Whereas their precise modification was hampered by the lack of insight into active centers.Here an X-ray photoelectron spectroscopy (XPS) technique was employed to study the interaction of various components,especially the central metal atoms in these catalysts.Copolymerization experiments with typical conditions were also carried out to investigate the correlation between the binding energy (BE) of central metals and the catalytic activity.The BE of Zn2p3/2 in Y(CCl3COO)3-glycerin-ZnEt2 ternary catalyst was tested to be 0.3 eV higher than that in glycerin-ZnEt2 binary catalyst,while the BE of O1s increased by 0.4 eV; On the contrary,the BE of Y3d5/2 in the ternary catalyst system decreased by 1.4 eV than that in Y(CCl3COO)3,while Cl2p decreased by 1.6 eV.The BE shifts showed that the rare-earth-metal compound has assuredly coordinated with zincoxygen bond in the ternary catalyst.Active center for the copolymerization is the coordinating activated zinc-oxygen bond,and rareearthmetal compounds shift the electron distribution of active center by a conjectured “double metal bridged coordinating" mode.Electrons around Zn partially flow to Y via coordinating,resulting in decrease of electron cloud density and increase of the Lewis acidity around catalytic centre.That makes the activated zinc-oxygen bond more liable to be attacked by carbon dioxide and epoxide monomer,thereby it enhances the catalytic activity.As a result,the activity of Y(CCl3COO)3 based ternary catalyst reached 563.0 g polymer/(mol Zn h) in the copolymerization,which is 23.6% higher than the activity of the binary catalyst system without rare-earth-metal compounds.Yttrium compounds with various anionic groups were also investigated to study the influences of Lewis acidity on central site.A consistent relationship was found among the pKa of ligands in yttrium compounds,BE of the coordinated catalysts and catalytic activities.
- 18
- |
- 11
- |
- 1
发布时间：2021-03-19 - 摘要：Abstract The kinetics of isothermal crystallization for isotactic polypropylene (iPP) containing different volume fraction (φCB) of carbon black (CB) was evaluated by using differential scanning calorimetry (DSC) at 137.5℃,139.5℃ and 141.5℃ with moderate rates of crystallization.Simultaneous measurements of rheological and conduction behaviors were performed to probe the process of isothermal crystallization in dynamic and static modes.It was found that when CB volume fraction φCB was 0.09,the characteristic time for sharp resistance variation was comparable to those for shape changes in storage modulus (G′) or normal force (FN).At φCB of 0.13 and 0.17 above the upper limit of percolation transition,however,the characteristic time resulted from resistance was much less than those from G′or FN,which could be explained by the formation of the percolation network during the induction period of crystallization.On the other hand,for all φCB and crystallization temperatures,the characteristic time from dynamical method was less than that from the static one,which indicated that the dynamical method was more sensitive to the structural transformation than the static one.It was suggested that rheological and electrical simultaneous measurements endowed us a novel approach to probe the formation of percolation network involving in crystallization of polymer matrix.
- 22
- |
- 13
- |
- 3
发布时间：2021-03-19 - 摘要：A novel cholesterol molecularly-imprinted polymerized organogel was prepared in present work.N-octadecyl maleamic acid (ODMA) as polymerizable gelator can self-assemble in polymerizable solvent mixture of β-hydroxyethyl methacrylate,methylacrylic acid and polyethylene glycol dimethacrylates-200 in the presence of 3-cholesteryloxycarbonylbonylpropanoic acid (COPA) as template,and ultimately turn them into organogels.The resultant organogels were subsequently polymerized by in situ UV irradiation.The molecularlyimprinting polymerized organogels were obtained after removal of the template through ethanol extracting.The images of polarized optical microscopy and field emission scanning electric microscopy of organogels indicated a number of branch-like crystallites which consisted of ODMA aggregates formed,which played an important role for the formation of stable imprinting cavities.The imprinted polymerized organogels exhibited higher adsorption efficiency(64%) for cholesterol.It was found that the adsorption capacity of the imprinted polymerized organogels depended on the contents of ODMA and COPA.For instance,the adsorption capacity increased from 15.7 mg/g to 22.9 mg/g with an increase of ODMA content from 1 wt% to 3 wt% in the matrix and increased from 16.8 mg/g to 22.2 mg/g with an increase of COPA content from 4 wt% to 7 wt%,respectively.However,the adsorption capacity decreased with further increase of ODMA and COPA contents mainly due to the high density of polymer network and interfering to the selfassembly of ODMA.
- 30
- |
- 13
- |
- 5
发布时间：2021-03-19 - 摘要：Ternary interpenetrating polymer networks (T-IPN) hydrogels composed of poly(vinyl acohol) (PVA),poly(acrylic acid)(PAA) and poly(2-acrylamido-2-methyl propyl sulfonic acid)(PAMPS) were synthesized by solution polymerization of acrylic acid (AA),2-acrylamido-2-methyl propyl sulfonic acid (AMPS) and PVA.Fouriertransform infrared (FT-IR) was used to confirm the chemical structure of the T-IPN hydrogel.In FT-IR spectra,the peak of C—O stretching shifts to low wave numbers.This is attributed to the formation of strong hydrogen bond between PVA and PAA and PAMPS.The crystallinity properties of T-IPN hydrogels were investigated by X-ray diffraction spectrogram (XRD) and scanning electron microscope (SEM).The results show that the hydrogel forms perfect IPN networks when the content of PVA is low.However,when the content of PVA is high,the crystallization of PVA increases,and phase separation is formed.The swelling properties of the T-IPN hydrogels were studied,the results show that the equilibrium swelling ratio of the T-IPN hydrogels ranges from 200 to 340.The T-IPN hydrogel exhibits completely different deswelling properties in acid solutions and basic solutions,and this T-IPN hydrogel exhibits discontinuous volume phase transition when the pH of the solution is about 9.0. The compression strength of T-IPN hydrogels was also studied.The results show that T-IPN hydrogels composed of linear polymer,flexible polymer network and rigid polymer network exhibit both high swelling ratio and high compression strength.When the swelling ratio of the T-IPN hydrogels is 180,the maximum compression strength of the hydrogel is about 12.1 MPa.Further investigation shows that the compression strength and compression strain are influenced by the composition and the swelling ratio of the hydrogels.
- 32
- |
- 18
- |
- 12
发布时间：2021-03-19 - 摘要：Delivery of synthetic small interfering RNA(siRNA) remains the major obstacle to the therapeutic application of RNA interference.A novel nanogel that composed of hydrophilic polyethylene glycol and cationic polyethylenimine for siRNA delivery was synthesized and characterized.The nanogel was synthesized via inverse microemulsion polymerization of polyethylenimine with Mw=800 and poly(ethylene glycol) diacrylate (Mw=400).The successful synthesis of the nanogel was demonstrated by 1H-NMR,FTIR characterizations.Dynamic light scattering measurements show that the nanogels have an average size of 180 nm,while the nanogels are positively charged with a zeta potential of 37.9 mV.Such nanogel is suitable for siRNA loading by electrostatic interaction,which has been further demonstrated by gel retardation assay.The cytotoxicity of nanogel against MCF-7 cellswas evaluated using MTT method and it showed no significant cytotoxicity effect even at high concentration up to 1.0 mg/mL.The siRNA delivery efficiency of nanogel was evaluated by silencing green fluorescent protein (GFP) expression in MCF-7 KMRV cells that stably expressed GFP.The results indicated that the nanogel induced high gene silencing effect,which was comparable to that of Lipofectamine 2000TM.With proper particle size,strong siRNA binding ability and efficient gene silencing function,this nanogel/siRNA formulation is potential for efficient siRNA delivery in therapeutical application.
- 42
- |
- 10
- |
- 3
发布时间：2021-03-19
Research Article
- 摘要：A technique of in situ SiO2 preparation in silicon-based ablationresistant material by sol-gel method was established.The preparing processes were as follows:first,vulcanizates were prepared by mechanical mixing of silicone rubber,fumed silica and other fillers.Secondly,the vulcanizates were swelle in tetrahydrofuran (THF) at 30°C for 12 h,and subsequently subjected to soaking in the tetraethylorthosilicate (TEOS) for 24 h.Thirdly,the swollen vulcanizates were put into the aqueous solution of n-butylamine at 50°C for 48 h in order to conduct the hydrolysis and condensation reactions of TEOS.Finally,the resultant vulcanizates were dried for several days at 50°C under a reduced pressure.SEM photographs indicated that silicon dioxide particles prepared by sol -gel method were spherical, and the particle size distribution was in the range of 40～60 nm,but the in situ SiO2 was dispersed differently in the vulcanizates,which was enriched in the surface than the inside.So the content of in situ SiO2 was the average of the materials. Compared to the conventional silicafilled vulcanizates which were prepared by mechanical mixing of the silica particles,the new vulcanizates with the in situ SiO2 showed better properties.The results showed that the tensile strength and the ablation rate were improved apparently when the average amount of in situ SiO2 increased.The tensile strength of the siliconbased ablation-resistant material containsing 13.7% in situ SiO2 was about 5.82 MPa, and the ablation rate was 0.071 mm/s.
- 13
- |
- 15
- |
- 3
发布时间：2021-03-19 - 摘要：The monodisperse SiO2-coated polystyrene (PS) (PS/SiO2) core-shell nanocomposite microspheres were prepared by a simple and low-cost method.The PS nanospheres were first synthesized in the presence of polyvinylpyrrolidone (PVP),and the SiO2 particles were subsequently coated on the surface of the PS nanospheres by sol-gel process in NH4OH/ethanol solutions.The preparation of the PS nanospheres is accomplished in aqueous media and has following advantages:no comonomer is needed,the cheap potassium persulfate (K2S2O8) radical initiator is used instead of the expensive azodiisobutyramidine dihydrochloride (AIBA) radical initiator,and no exchange of the solvent and no centrifugal process are needed before the process of coating the SiO2 particles on the PS nanospheres.The influences of the content of the PVP,NH4OH,and tetraethyl orthosilicate (TEOS) on the size and morphology of the PS/SiO2 nanocomposite microspheres were investigated.With increasing the content of PVP,the size of the PS nanospheres decreased,and thus smaller PS/SiO2 nanocomposite microspheres were obtained.The content of NH4OH did not affect the thickness of the SiO2 shell,bus it influenced the morphology of the SiO2 shell.The surface of the SiO2 shell changed from smoothness to roughness with increasing content of NH4OH.With increasing content of TEOS,the generated SiO2 particles increased,and thus the thickness of the SiO2 shell increased.
- 26
- |
- 15
- |
- 1
发布时间：2021-03-19 - 摘要：Natural biopolymer chitosan has been investigated widely for a variety of biomedical applications due to its excellent biocompatibility and biodegradability.The toughness of chitosan porous scaffolds is good,but the strength is low.It is suggested that the coating treatment of hydroxyapatite will improve the strength and osteoconductivity of the scaffolds,and maintain the toughness still.In this research,the electrochemistry assisted deposition method was used to deposit hydroxyapatite on the pores’ surface of porous scaffolds.Calcium and phosphate ions in anode and cathode solutions moved directionally in the electric field,reached the internal of scaffolds and reacted and deposited,so the organic-inorganic composite scaffold was obtained.The composition,morphology,inorganic deposition amount,porosity and compressive strength were characterized by XRD,SEM,calcination,porosity measurement,and compression experiment.It was shown that the hydroxyapatite coating with low crystallinity deposited on the pores’ surface of scaffolds.The coating was uniform and dense at low magnification,but there was a great deal of micropores in the deposition layer at high magnification,and some spheres on the layer composed of small hydroxyapatite lamellae.After being treated 6 h,the deposition amount was 2.81% of total weight, and the porosity was decreased from 96.0% to 89.8%.The compressive strength of the treated scaffold was increased to 0.0998 MPa comparing with 0.0550 MPa of the chitosan scaffold.
- 14
- |
- 12
- |
- 5
发布时间：2021-03-19 - 摘要：To develop and characterize a new class of potential blood pool magnetic resonance (MR) contrast agents which could be used as cancer target gene delivery carrier,novel gadolinium amino group terminated poly(ether-urethane-amide)/diethylenetriamine pentaacetic acid (PEU-Gd-DTPA) polymeric chelate（Ⅳ）was synthesized.The amino group terminated poly(ether-urethaneamide)/diethylenetriamine pentaacetic acid (PEU/DTPA) copolymer ligand （Ⅲ）could be designed and obtained from the reaction of diethylenetriamine pentaacetic acid dianhydride (DTPAA,Ⅰ) with amino group terminated PEU (PEU-((CH2)6NH2)2) （Ⅱ）,which was prepared in high yield by the reaction of polyethylene glycol (PEG) with isophorone diisocyanate (IPDI) and then with hexamethylene diamine.Ligand Ⅲ was then coordinated with Gd3+ ion to give the macromolecular contrast agent Ⅳ in water at room temperature.The structure analysis and characterization of DTPAA,Ⅱ,Ⅲ were studied by IR,NMR,GPC,and functional group titration methods.Gadolinium content of the polymeric chelate Ⅳ was 088 wt%,which was determined by radio frequency inductively coupled plasma (ICP) spectra.In vitro- relaxivity (R1) studies of Ⅳ showed a 38.40% increase in R1 relaxivity compared with gadoliniumdiethylenetriamine pentaacetic acid dimeglumine (Gd-DTPA) injection.The R1 values for Gd-DTPA and Ⅳ were 5.93 and 8.21(mmol/L)-1#8226;s-1,respectively.In vivo distribution of Gd-DTPA and Ⅳ was studied at magnetic resonance imaging (MRI) before injection,0.1,6,12 and 24 h after injection,with assessment of liver signal intensity (SI) in 10 nude mice.The liver signal enhancement rates of Ⅳ at 0.1,6,12 and 24 h are 1.5,3,1.8 and 1.3 times,respectively,compared with the largest signal intensity 0.33 of GdDTPA observed at 0.1 h.The half-life of Ⅳ in liver was as longer as 24 h,while no signal enhancement was observed after 6 hours injection of Gd-DTPA.Ⅳ had also a longer circulation life.
- 17
- |
- 12
- |
- 5
发布时间：2021-03-19 - 摘要：Poly(aryl ether ketone)s are considered as a kind of important highperformance polymers due to their excellent thermal stability,resistance to corrosion,creep and other outstanding properties.However,the PEK’ s insolubility in common solutions and high melt point restrict its processing and application.In this paper,above all,a novel monomer,1,3-di(4-chloro formyl benzoyl) benzene (DMBC) was synthesised and confirmed by FT-IR, 1H-NMR and so on.Then three poly(aryl ether ketone)s containing multi-carbonly in their main chains were prepared by low temperature solution polycondensation of DMBC with 4,4′-diphenoxydiphenylsolfone (DPODPS),1,3-di(4-phenoxybenzoylbenzene (i-DPOPKK)and 1,4-di(4-phenoxybenzoyl)benzene (p-DPOPKK) in 1,2-dichloroethane (DCE) with the presence of AlCl3 and DMAc.The structure of polymers (Pa,Pb,Pc) obtained were characterized by FT-IR and 1H-NMR.The inherent viscosities (ηinh) of them are above 0.70 dL/g.WAXD studies reveal that the three polymers have the same crystallization diffraction pattern as PEKK,which belongs to rhombic system,so all of them also belong to rhombic system.Thermal properties of the polymers were obtained by DSC and TGA.DSC analysis indicates that compared to PEKEKK and PEKK,the glass transition temperature (Tg) of polymers is improved,and the melting temperature (Tm) decreases.All of the polymers also show high thermal stability with 5% weight-loss temperature over 519℃ according to TGA.Compared to PEKEKK and PEKK,the solubility of polymers is also improved,especially with the introducing of sulfonyl and more isophthaloyl.
- 12
- |
- 13
- |
- 1
发布时间：2021-03-19 - 摘要：An amphiphilic block copolymer functionalized with strong pushpull azobenzene moieties,PEG-b-P6CNAzo,was synthesized through a scheme that combined ATRP and post-polymerization azo-coupling reaction.First,the precursor diblock copolymer,PEG-b-P6MA,containing aniline groups was prepared by a PEGBr initiated ATRP of monomer 6(N-methylanilino)hexyl methacrylate.Then PEG-b-P6CNAzo was obtained through azo-coupling reaction between PEG-b-P6MA and diazonium salt of 4-aminobenzonitrile.The azo block copolymer was carefully characterized by GPC,1H-NMR and UV-Vis.The polymerization degree of PEG-b-P6MA was 122-b-13,which was obtained through 1H-NMR analysis.Due to the high yield of azo-coupling reaction,the polymerization degree of PEG-b-P6CNAzo was also 122-b-13,the same as PEG-b-P6MA.GPC results revealed that both PEG-b-P6MA and PEG-b-P6CNAzo had narrow molecular weight distributions.By adding water under a rate of 0.5 mL/h to its THF solution with the concentration of 0.2 g/L,PEG-b-P6CNAzo formed rod-like micelles with diameter of ca.11 nm obtained by TEM observation.
- 18
- |
- 15
- |
- 2
发布时间：2021-03-19
Research Bulletin
- Postal code：100190
- Tel：010-62588927 Email：gfzxb@iccas.ac.cn
- Technical support is provided by Beijing Founder electronics co., LTD 京ICP备05002797号-8
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0