jlu高分子材料review

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1、高分子材料Review20131. Polymer Natural polymer: wool, wood, cotton, silk, cellulose, cheese, etc. Synthetic polymer: rubber, fiber, plastics, coating, adhesive, man-made leather. Differences between polymers and small molecules: molecular size, distribution, melting point, volatilizationClassification(1)

2、 Material PropertyThermoplastics, Thermosets (2) Polymerization MechanismAddition polymersCondensation polymers(3) Main-Chain StructureCarbon-carbonCarbon-oxygenCarbon-sulfurCarbon-nitrogenSilicon-oxygen(4) PerformanceIntelligent (smart) polymerOrganic nanomaterials1.Please explain the following con

3、cepts. Thermoplastics, Thermosets, Functional polymers, Addition polymers, Condensation polymersQuestions 2. Polymer structureLong-chain molecules composed of a large number of repeating units of identical structure (MW: 103 107). -repeating-unit1-x-repeating-unit2-y-repeating-unit3-z- Y=0, Z=0: PS,

4、 PE, PP, PET. Y0, z=0: X Y Z 0: ABS Monomer, repeating unit, structural unit, nomenclature, abbreviation -CH2-CH2-n-CCababCCabab顺式反式CCabCCab顺式反式cdcd顺反异构Configuration构型aaCCaabCCaab不是顺反异构Trans-cis (Geometric) isomerization几何异构几何异构 Configuration:an arrangement of atoms that cannot be altered except by

5、breaking chemical bonds. Geometric Isomerism（立体异构）（立体异构） Several different isomeric forms are possible, where there are unsaturated sites along a polymer chain. -CH2-CH- H3C-C=CH2 H2C=CH-CCH3=CH2-CH2 CH2- -CH2 H C=C C=C CH3 H CH3 CH2-互为旋光异构，各有不同的旋光性CH2HXCnOptical isomerism 两者互为旋光异构体H2CCH2XHHXCH2H2CC

6、CTacticity（立构规整度）Isotactic（全同立构）（全同立构）: all the R groups lie on the same side of the plane formed by the extended-chain backbone.Syndiotactic: the R groups regularly alternate from one side to the other side. Atactic: the R groups with no preferred placement in the chains.morphology, conformationnmD

7、nmL5 . 0,105 . 24DL4105DLPlymer chainthe individual, recognisable arrangement of atoms that can be altered by simple rotation around a single bond.HCHCCCHHHHHHHHHH迭同式（顺式）构象最不稳定交叉式（反式）构象最稳定或或0000360,240,120,0000300,180,60Questions1. What is the difference between conformation and configuration? Which

8、 type does a helix isotactic PP belong to? If the tacticity of PP is low, can we increase it by rotation of single bond to change the conformation? Why? 3. Molecular WeightiiiMnW iiiiiwmMmM/iiiMWz iiiZMZzM/Number-averageWeight-averageZ-averageMw/Mn (PDI)Radical: 1.5-2.0High yield: 2-5Self-accelerati

9、on: 5-10Anionic: 1.01-1.05Coordination: 8-30Grafting: 20-50Molecular Weight DistributionQuestions1 Consider three samples of polyisobutylene. All molecules in sample A have a molecular weight of 30,000g/mol; all those in B have a molecular weight of 70,000 g/mol; and those in C have a molecular weig

10、ht of 100,000 g/mol. If 10g of A are mixed with 5 g of B and 1g of C, calculate Mn, Mw, and Mz. (section 2) Give their relationship. Draw a curve of MW distribution and mark statistic various MWs on it. Questions 2Nylon-66 can be prepared from the monomers of hexanediamine and adipic acid though Ste

11、pwise Polymerizations, if adipic acid is excessive, and the reaction extent (P) is 0.994, the molecular weight is 13500, please write the chemical equation of the reaction between hexanediamine and adipic acid, please calculate the ratio of the two monomers. (section 3)4. Difference between radical

12、and condensation polymerizationsCondensation polymerization1. Most of reactions are reversible.2. Polymers grow stepwise.3. Any two molecular species can react.4. Monomers disappear in the early stage of reaction.5. Molecular weight of polymer rises steadily throughout reaction.6. At any stage all m

13、olecular species are present in a calculable distribution.Radical polymerization1. Most of reactions are irreversible.2. Polymers grow chain-reacting.3. Only growth reaction adds one repeating unit at a time to the chain.4. Monomer concentration decreases steadily throughout reaction.5. High polymer

14、 is formed at once, polymer molecular weight changes little throughout reaction.6. Long reaction times give high yields but affect molecular weight little.7. Reaction mixture contains only monomer and high polymer.Stepwise Polymerization1. Polymerization characteristics2. Function degree, Relationsh

15、ip of reaction extent (P) with polymerization degree (Xn) and ratio of monomers ( r)3. Control of Molecular Weight4. Polymerization Techniques5. Non-linear PolymerizationChain-Growth Polymerization1. Basic reaction: Initiation; Propagation; Termination; Chain-transfer2. A. Initiator initiation; B. H

16、eat initiation; C. Photoinitiation; D. Radiation initiation.3. Polymerization Techniques5. Glass transition temperature Tg Concept Chemical structure Main-chain Side-group: size,Tg; flexibility,Tg ; symmetry,Tg ;, space order ,Tg Effect of crosslinking structure on Tg PS 87C; 0.6% bivinyl-benzene, 8

17、9.5C; 1% 94C; Tg of copolymer Tg = V1Tg1 + V2Tg2; 1/Tg = w1/Tg1 + w2/Tg2 V volume portion; W: mass portion Plasticizer: PVC 81C, 45% P -30CQuestion What is Glass Transition Temperature（Tg）? Is Tg increased all the time with the molecular weight of a polymer increasing from low to ultra-high one? Poi

18、nt out the effect of these factors to Tg: Plasticizer, crosslinking, side-group size, side-group flexibility, side-group symmetry, side-group space order. 6. Radical polym. mechanism1. Initiation (1) I-I 2I (2) I + M IM 2. Propagation IM + M IMM3. Chain-transfera. Monomer Mn + M MnH + M1 b. Solvent

19、IMx-1M + SH IMx-1MH + S c. Macromolecules Mn + Mx-CHX-My MnH + Mx- CX-My 4. Termination a. Combination: IMx-1M + MMy-1I IMx-1MMMy-1Ib. Disproportionation IMx-1M + MMy-1I IMx + MyI I-I: initiator; I.: radical; M: monomre; SH: solventQuestion : Write the set of elementary reactions that comprise the f

20、ree radical chain polymerization of vinyl acetate and methyl methacrylate, when the process is initiated by azobisisobutyronitrile. If carbon tetrachloride is added to the systems, describe the effects of chain transfer with carbon tetrachloride on the polymer composition and average molecular weigh

21、t.H3CCCH3CNNNCCH3CNCH3H3CCCH3CNNN+2H3CCCH3CNH2CCHOOCCH3H3CCCH3CNH2CCHOOCCH3+H3CCCH3CNH2CCHOOCCH3H2CCHOOCCH3+H3CCCH3CNH2CHCOOCCH3H2CCHOOCCH3H2CCHOOCCH3(n-1)H3CCCH3CNH2CHCOOCCH3H2CCHOOCCH3n链引发（Chain Initiation）：链增长（Chain Propagation）：vinyl acetateH3CCCH3CNH2CHCOOCCH3H2CCHOOCHCH2nCH3CCH3CNH2CHCOOCCH3H2

22、CHCOOCCH3m+H3CCCH3CNH2CHCOOCCH3CHCHOOCCH3nCH3CCH3CNH2CHCOOCCH3H2CH2COOCCH3mH3CCCH3CNH2CHCOOCCH3H2CCHOOCCH3nCCl4H3CCCH3CNH2CHCOOCCH3H2CCHOOCCH3nCl+CCl3链终止（Chain Termination）：当加入四氯化碳（carbon tetrachloride）时：这样会导致聚合度下降,因而分子量会下降。7. Tensile strengthTensile strength measures how difficult it is to break a

23、substance when stress is applied to pull it apart. Y- Stress at the yield point1- Elongation at the yield point2- Stress at Fracture2- Elongation at Fracture The stress-strain curves of two polymers are as follows. Please show their differences based on polymer structures.8. High performance plastic

24、s Question: Give an example of high performance plastics that is able to withstand temperature above 350C and explain why. PEEK: molecular structure, monomer, polymerization type, and property.OOCOnHOOHCOFF分子结构：单体：逐步聚合9. Polymer processingExtrusion: A continuous process to produce thermoplastics in

25、forms of band.Compression and heat molding Molding is mainly for the processing of thermosets. Liquid or melted materials are poured into a mold and there “hardened, i.e., polycondensed or polymerized. Phenol and epoxy resins are processed in this manner, as are styrene, acrylate et al.Injection: A

26、reciprocating screw is used to melt a measured volume of feed. And the melt is rammed into a mold under high pressure by a hydraulically driven thrust of the screw (thermosets).Blow molding: A gas is used to expand a hot preform, against the form of a mold cavity to produce a hollow object. Two proc

27、ess are used for blow molding - injection and extrusion (thermoplastics). Calendering: Molten polymer is compressed in the small gap between two heated cylinders rotating in opposite directions to produce sheets.Coating: Solutions, melts or dispersions are applied to a base. The base may be the poly

28、mer, itself, or may consist of different materials. It can remain bound to the polymer used after the process, or it may be removed.Spinning: dry-spinning, wet-spinning, electrospinningQuestion : Which processes are used for fabrication of the following matters: rubber gloves, plastic film, bottle,

29、isolation sheet for cable, man-made leather, polyester fiber, air balloon, computer shell, throw-away cup, car bumper, coating, and nanofibers ?10. ElectrospinningQuestion: Please decribe the mechanism of the elelctrospinning process. Is it possible to produce nanotubes, nanocables, nanocomposites b

30、y electrospinning? How? 在静电纺丝过程中,将聚合物熔体或溶液加上几千至几万伏的高压静电,从而在毛细管和接地的接收装置间产生一个强大的电场力。由于电场力和表面张力共同作用下，液滴将被拉伸成圆锥状（Taylor锥）。当电场力大于表面张力时，聚合物熔体或溶液经过喷丝板的孔眼后，在电场中被拉伸,最终在接收装置上形成纳米纤维。11. Universal Polymer MaterialsPlastics RubberFibersAdhesive Coatings1) additives 1. Plastics（一）（一） Typeslubricant, thermal stabi

31、lizer: beneficial for processing；fillers, reinforcing agent, impact modifier, plasticizer:flame retardant: improve flame retardancy stabilizer: improve aging resistance2) Universal plasticPolyolefin plastic: PE, PP, PS (ABS, ACS)Polyamide: nylon 6, nylon 66, nylon 610, nylon 1010.Polycarbonate:Polyo

32、xymethylene:PolysulfoneP(ether ether ketone)2. RubberClassification:Nature rubber聚丁二烯橡胶聚丁二烯橡胶聚异戊二烯橡胶聚异戊二烯橡胶丁苯橡胶丁苯橡胶丁腈橡胶丁腈橡胶氯丁橡胶氯丁橡胶丁基橡胶丁基橡胶Processing:What is rubber sulphuration? Please describe the main process of the rubber sulphuration. 12. Conducting polymer Proton doping Polyacetylene: Conducti

33、vity is increased to 105 S/cm Polyaniline: 103 S/cm Doping characterization Reversibility: doping-dedoping charge-dischargeQuestionsGive three kinds of polymers which are conductive after doping. Describe the chemical equation for the reaction between aniline and (NH4)2S2O8 in the presence of hydroc

34、hloric acid. Give the molecular structures of three forms of polyaniline (oxidative state, reduce form, and EB state). Why are the conductivity of polyaniline different with change in pH values ? 12. Nanopolymers Nanoparticles (0D) micro-emulsion electrospray Nanofiber (1D) electrospinning template

35、seed technique Nanofilm (2D) layer-by-layer L-B film self-assemblyNanocomposites (Organic/inorganic hybrid materials)Nano/macro Prepare colloids in polymer solution Blend colloids with polymer solution Polymerization in inorganic phase (inserting) Nano/nano Nanoparticles in nanofiber Nanoparticles i

36、n nanofilm Core/shell (embed, suspension, dispersion, emulsion)Nanoeffect Inorganic nanoparticles: - Surface effect S D2 V D3 S/V D 10nm 90m2/g, 5nm 180 m2/g, 2nm 450m2/gD(nm) 1 2 4 10T.N.A. 30 2.5X102 4 X103 3X104T.N.S.% 99 80 40 One layer surface atoms Metals burnt in air Inorganic particles react

37、 with gas. - High surface activity - Small-size effect Specific change in macrophysical properties caused by the reducing of particle sizeA. optical property (Au, Pt, Cr :black) B. Thermal property (Au 1064C, 10 nm 1037C; 2 nm 327C, Ag 670- 570C, W+Ni 0.1-0.5% 3000-1200C)C. Magnetic property (Fe 80A

38、/m, 20 nm 1000times, 6 nm superparamagnism)D. Mechanic property (ceramic: brittle-tough )- Quantum Tunneling Effect Energy splitting Conductor insulator Spectra move to short wavelength Quantum resonance tunneling transistorOrganic polymer: Hydrophilic-hydrophobic Tg Conductivity Mechanic strength Charge Wavelength shift Questions: Find the nanoeffects of organic polymers. Predict the nanoeffects of inorganic/organic nanocomposites.