最新刊期
卷 24 ， 期 7 ， 2011
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Research Progress of Pd Catalyzed Cross-coupling Reactions Utilized in Solid Phase Organic Synthesis
摘要：Coupling reaction using transition metal Pd as catalyst has been very efficient in formulating C-C bond , thus Pd catalyzed C-C coupling reaction has been under spotlight of scientist s' attention for years and series of derivative reactions were thence developed , among which Pd catalyzed Solid-phase organic reactions suck as Heck reaction 、Negishi reaction 、Suzuki coupling and Stille coupling ,with their accessible reaction conditions , high tolerance of diverse functional groups , low steric hindrance , excellent chemical selectivity ,mild toxicity , side products friendly and removable , efficient in yields , have always been the researching focus of catalytic chemistry and solid phase combinatory chemistry .With reference to different classification standards and our own research work , this article reviews the researching progresses of Pd catalized Cross-coupling reactions used in solid phase organic synthesis reactions , such as Heck/Negishi/Suzuki and Stille reaction .关键词：Palladium catalyzed cross-coupling reactions;Heck reaction;Negishi reaction;Suzuki coupling;Stille coupling;Solid phase synthesis;Combinatoryal chemistry- 2
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发布时间：2022-09-18 - 摘要：Compared with conventional multi-coating system , self-stratification coating , capable of producing multilayer structure in one operation , results in outstanding interfacial adhesion , low production cost and long service life .In this article , the self-stratifying processes and corresponding driving forces have been reviewed and suggested , and the various factors effecting on self-stratification have been discussed in detail .The progress in self-stratification coating based on solventborne , waterborne and solventless coatings has been expatiated .The coating has widely been applied in many fields , and its investigation should focus on environmentally friendly coating for the future .关键词：Self-stratification coating;Compatibility;Surface tension;Environmentally friendly
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发布时间：2022-09-18 - 摘要：In this paper,theory and application of mesoscopic simulation methods,which include Monte Carlo,Cellular Automata and Dissipative Particle Dynamics,are summarized.Especially the application of Dissipative Particle Dynamics method in the simulation of material field was reviewed, such as the study of aggregation behavior of block polymer in aqueous solution,the interaction of surfactant and polymer,the study of complex fluid flows and microphase separation of block polymer. Furthermore,application of Dissipative Particle Dynamics in melt electrospinning is preliminary explored by author.Lastly,the advantage and potential of Dissipative Particle Dynamics method in mesoscopic simulation of materials were pointed out.关键词：Mesoscopic simulation;Dissipative particle dynamics;Monte carlo;Cellular automata
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发布时间：2022-09-18 - 摘要：Due to its long chain structure,long chain branched polyethylene (LCB-PE) shows much excellent rheological behavior than the other polyethylene structure and can be used to modify the polymer process.Now,radiation,metallocene catalysts and hydrogenation of polybutadiene methods were used to prepare LCB-PE.In this paper,the principle,advantage and disadvantage of each method were reviewed.The radiation method can be easily applied in the industry scale.But the detail structure of the LCB-PE is hard to be characterized,and the equipment is highly requested to resist the high energy radiation.The preparation process of LCB-PE by metallocene catalysts can be easily controlled, and the LCB-PE can be characterized clearly.However,the technology is hard to application in China because the patents about metallocene catalysts.The LCB-PE prepared by the hydrogenation of polybutadiene method is well-controlled and well-defined,the length of main chain and branch chain and the density of branch all can be controlled,but he produce is too complex and the cost is too high.关键词：Polyethylene;Long chain branched;Progress
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发布时间：2022-09-18 - 摘要：Drug delivery system of microspheres can realize the target delivery of drugs .They exhibit a good prospects in the sustained-release and controlled-release drug delivery systems .In recent years , the application of pharmaceutical microspheres had been one of the research focus .Polymer carriers are developmented with pharmacology , biomaterials and clinical medicine , they are pharmaceutical excipients which possess excellent biocompatibility , biodeg radability , processing property and meeting safty standard .They include ethyl-cellulose , starch , chitosan , alginate , gelatin , silk fibroin , albumin , zein , PLA and PLGA .Currently , the application of polymer carriers on the pharmaceutical microspheres is attractive to the pharmacists .Based on the degradability , the polymer carriers can be divide into non-degradable and degradable polymer .This review summarizes the application and advances on the different types of polymer carriers for the pharmaceutical microspheres .关键词：Carriers;Non-degradable polymer materials;Degradable polymer materials;Pharmaceutical microspheres
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发布时间：2022-09-18 - 摘要：As an important biodegradable material,polylactic acid (PLA) has been extensively applied in many fields,including biomedical polymers.Monosaccharides have good affinity to peptide and protein and have good compatibility with tissue cell.In order to improve the properties of PLA, especially hydrophilicity and cell compatibilities,more and more importance have been attracted to monosaccharides modified PLA.According to the types of monosaccharides,the recent progress on the modification of PLA by different monosaccharides and their derivatives,have been reviewed in this article.It is pointed that the direction of PLA modification involving the utilization of biological resources and functionalization of PLA material should be noteworthy,and the research on the modification method via melt copolymerization direct using inexpensive lactic acid as starting material should be strengthened.关键词：Polylactic acid;Monosaccharides;Modification
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发布时间：2022-09-18 - 摘要：Dendronized polymers are the ideal supports for the homogeneous catalysts with the characters of many intramolecular cavities,dense reactive groups in the periphery and nanosize. Dendronized polymer catalysts combine the advantages of homogeneous catalysts and heterogeneous catalysts,providing high activity and selectivity under mild conditions.This paper introduces the synthesis of dendronized polymers and emphases on the synthesis and catalysis of dendronized polymer catalysts,and looks forward to the developing prospect of dendronized polymer catalysts.关键词：Dendronized polymer;Catalyst;Support
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发布时间：2022-09-18 - 摘要：This paper characterized the spin coating thin film made of polyoctylfluorene (PFO) toluene solution which be dissolved for 12min,30min and 50min respectively under the 55℃ by photoluminescence spectra,UV-Visible spectra and atomic force microscope.The results indicate that the PFO thin film made of solution dissolving for shorter time contains large gel particles with average size of 120nm×80nm,which lead to partly β phase photoluminescence.When dissolving time become longer,large particles disappear and the photoluminescence spectra was totally of amorphous phase. After solvent vapor treatment or thermo annealing the residual gel particle structure still remain,which decrease photoluminescence.These results indicate that the residual gel in the solution has negative effects on luminous property of film.关键词：Polyoctylfluorene thin film;Gel;Photoluminescence
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发布时间：2022-09-18 - 摘要：A special Polyurethane (PU) Elastomer with good mechanical property was prepared from Isophorone diisocyanate (IPDI) according to literature.Heparin has been grafted onto the surface of the PU elastomer and PU-Hep elastomer was obtained.By immersing the PU elastomers in dilute gelatin aqueous solution and measuring the viscosity of the solution at different time,concentration and temperature,we found that the gelatin macromolecules accumulated on the surface of PU elastomer as soon as they contacted.However,it need a long time to reach the adsorption equilibrium.The amount of adsorption for gelatin was calculated from experimental relative viscosity data using a viscosity equation with interfacial effect correction.The result showed that in the range of 35℃~42℃,along with the increasing of the temperature,more gelatin macromolecules has been adsorbed on the surface of the PU elastomer,and the PU-hep elasomer showed larger adsorption capacity.关键词：PU elastomer;Gelatin solution;Adsorption;Viscosity
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发布时间：2022-09-18 - 摘要：Double-deck collagen/p( 2-methacryloyloxyethyl phosphorylcholine) ( pMPC) membranes for guided tissue regeneration were prepared through electrospinning/solution casting method . Chemical structure of pMPC, the interaction and miscibility between pMPC and collagen was respectively characterized by nuclear magnetic resonance ( NMR) , fourier transform infrared spectroscopy ( FTIR) and thermogravimetric analysis ( TG/DTG) . The surface morphology , elementary composition and hydrophilicity were characterized by scanning electronic microscope( SEM) , X-ray photoelectron spectroscopy measurements( XPS) and static contact angle measurments( SCA) , respectively .The results indicate that the blending of pMPC and collagen was optimum when the weight content of pMPC was 20 %;the introduce of pMPC into matrix could improve largely the surface hydrophilicity .关键词：2-Methacryloyloxyethyl;Phosphorylcholine;Collagen;Miscibility;Elementary composition
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发布时间：2022-09-18 - 摘要：The high-ortho and high molecular weight thermoplastic phenolic resin was synthesized by using formaldehyde and excessive phenol as reactants in the absence of catalysts under high pressure and high temperature conditions.The influences of various parameters such as reactant type,the ratio of raw materials,reaction temperature and pressure on the structure and properties of the resultant phenolic resin were investigated.The softening point,O/P (ortho/para) value,the content of free phenol,gel time and flow distance of the resins were analyzed.The high-ortho and high molecular weight thermoplastic phenolic resin with a softening point of 119∙5℃,O/P value of 1∙92,free phenol content of 1∙89%,a yield of 90%,gel time of 28s and flowing distance of 1∙8cm was successfully synthesized.关键词：Phenolic resin;High-ortho;High molecular weight
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发布时间：2022-09-18 - 摘要：This paper introduces the preparation of cellulose cholesteric liquid crystal by hydrolysis, the formation mechanism of phase separation,the texture and factors of liquid crystal and the applications.关键词：Cellulose;Cholesteric liquid crystal;Texture;Application
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发布时间：2022-09-18 - 摘要：Magnetic resonance imaging (MRI) contrast agents are used widely in clinical use.The advantage of macromolecular contrast agents was explained by relaxation theory.The chemical structures and development of the contrast agents were also introduced in this review. The paramagnetic Gadolinium (Ⅲ) chelates were modified by synthetic polymers,naturally occurring polymers,targeted agents and fluorescent labeled agents.It is indicated that the specific effects of modified contrast agents such as targeting and florescent labeled would raise the relaxation rate and reduce the toxicity.关键词：Contrast agents;Magnetic resonance imaging (MRI);Relaxation theory;Fluorescent labeled;Macromolecular ligands;Targeted agents
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发布时间：2022-09-18 - 摘要：The effect of condensed structure on cohesive energy density of polymer has always been ignored in the field of polymer physics.A method for estimating the CED value of crystalline non-polar polymers based on heat of fusion was first proposed in this paper.And the CED value of Poly (tetrafluoroethylene),Polyethylene and Polypropylene in crystalline were estimated.The estimated CED value better explained those polymers for plastics but with lower CED value.Heat of fusion essentially reflects the difference of intermolecular dispersion forces in non-polar polymer between crystalline and amorphous state.Estimating the cohesive energy density of crystalline non-polar polymer based on heat of fusion responds to the definition of cohesive energy density and its characteristic.In theory,the estimating method applied to all crystalline non-polar polymers.关键词：Cohesive energy density;Solubility parameter;Crystalline non-polar polymer;Heat of fusion;Estimation
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发布时间：2022-09-18 - 摘要：It is quite important to understand the basic principles and concepts of polymer physics deeply and apply them skillfully , which is useful for studying the "polymer physics" course , going in for the researches dealing with polymers , or doing the relevant practical works .In view of this , the author presents a way based on his teaching experience .This way focuses on increasing the portion of studentsprincipal role in teaching and learning activity via conducting special topic seminars .In doing this , the students are able to deepen their understanding on the principles of polymer physics , and to learn and apply them effectively .As a result , the teaching and learning activity is carried out well .关键词：Polymer physics;Understanding;Application;Seminar
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发布时间：2022-09-18 - 摘要：This paper discusses the teaching methods of polymer chemistry experiment based on the actual situation of the author’s university.To excite interest and initiative of students,and improve the teaching quality,the core of polymer chemistry should be embodied on experiment course.Experiments should be interesting and applicable and matching with the theoretics teaching.Schedule of experiments should be reasonable.Pre-experiment is necessary,as well as comprehensive experiment and design experiment.关键词：Polymer chemistry experiment;Teaching method;Discussion
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发布时间：2022-09-18 - 摘要：In order to make the students better improve and grasp the academic knowledge, combining our teaching practice,we opened the polymer chemistry experiment with the polymer chemistry being opened and introduced the characteristics of the open experiment " design, comprehensive" into polymer chemistry experiment in the teaching process.By designing experiments to make the students become the real master of learning,deep understand and master the knowledge of polymer chemistry theory;by adding the comprehensive experiment,to make the students know the frontier of polymer chemistry,and improve their academic interest,thus improve their learning initiative and scientific research capabilities,then process them to an utilized produce in this course.关键词：Polymer chemistry;Experiment;Open;Design
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发布时间：2022-09-18
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