1、高分子材料Review2013,1. 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, volatilization,Classification,

2、(1) Material Property,Thermoplastics, Thermosets,(2) Polymerization Mechanism,Addition polymers,Condensation polymers,(3) Main-Chain Structure,Carbon-carbon,Carbon-oxygen,Carbon-sulfur,Carbon-nitrogen,Silicon-oxygen,(4) Performance,Commodity polymer,High performance polymer,Functional polymer,Intell

3、igent (smart) polymer,Organic nanomaterials,Please explain the following concepts. Thermoplastics, Thermosets, Functional polymers, Addition polymers, Condensation polymers,Questions,2. Polymer structure,Long-chain molecules composed of a large number of repeating units of identical structure (MW: 1

4、03 107). -repeating-unit1-x-repeating-unit2-y-repeating-unit3-z- Y=0, Z=0: PS, PE, PP, PET. Y0, z=0: X Y Z 0: ABS Monomer, repeating unit, structural unit, nomenclature, abbreviation,-CH2-CH2-n-,Configuration構(gòu)型,Trans-cis (Geometric) isomerization 幾何異構(gòu),Configuration:an arrangement of atoms that canno

5、t be altered except by breaking chemical bonds.,Geometric Isomerism（立體異構(gòu)）,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-,Optical isomerism,Tacticity（立構(gòu)規(guī)整度）,Isotactic（全同

6、立構(gòu)）: 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, conformation,long-range structure,Plymer chain,f

7、lexibility,CC，CO，CN,bond,Conformation: the individual, recognisable arrangement of atoms that can be altered by simple rotation around a single bond.,conformation,Questions,1. What is the difference between conformation and configuration? Which type does a helix isotactic PP belong to? If the tactic

8、ity of PP is low, can we increase it by rotation of single bond to change the conformation? Why?,3. Molecular Weight,Number-average,Weight-average,Z-average,Mw/Mn (PDI) Radical: 1.5-2.0 High yield: 2-5 Self-acceleration: 5-10 Anionic: 1.01-1.05 Coordination: 8-30 Grafting: 20-50,Molecular Weight Dis

9、tribution,PS: 2 - 5 (comm.) PE: 30 PS: 1.06 (living) Mz Mw Mn,Questions1,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 weight of 100,000 g/mol. If 10

10、g 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 2,Nylon-66 can be prepared from the monomers of hexanediamine and adipic acid though Stepwise Polymerizations, if

11、 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 and condensation polymer

12、izations,Condensation polymerization 1. 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 molecular species

13、are present in a calculable distribution. Radical polymerization 1. 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 is formed

14、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 Polymerization,Polymerization characteristics Function degree, Relationship of reacti

15、on extent (P) with polymerization degree (Xn) and ratio of monomers ( r) Control of Molecular Weight Polymerization Techniques Non-linear Polymerization,Chain-Growth Polymerization,Basic reaction: Initiation; Propagation; Termination; Chain-transfer 2. A. Initiator initiation; B. Heat initiation; C.

16、 Photoinitiation; D. Radiation initiation. 3. Polymerization Techniques,5. 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, 89.5C; 1% 94C; Tg

17、 of copolymer Tg = V1Tg1 + V2Tg2; 1/Tg = w1/Tg1 + w2/Tg2 V volume portion; W: mass portion Plasticizer: PVC 81C, 45% P -30C,Question,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? Point out the effe

18、ct of these factors to Tg: Plasticizer, crosslinking, side-group size, side-group flexibility, side-group symmetry, side-group space order.,6. Radical polym. mechanism,1. Initiation (1) I-I 2I (2) I + M IM 2. Propagation IM + M IMM 3. Chain-transfer a. Monomer Mn + M MnH + M1 b. Solvent IMx-1M + SH

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

20、l 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 weight.,鏈引發(fā)（Cha

21、in Initiation）：,鏈增長（Chain Propagation）：,vinyl acetate,鏈終止（Chain Termination）：,當(dāng)加入四氯化碳（carbon tetrachloride）時：,這樣會導(dǎo)致聚合度下降,因而分子量會下降。,7. Tensile strength,Tensile strength measures how difficult it is to break a substance when stress is applied to pull it apart. Y- Stress at the yield point 1- Elongatio

22、n at the yield point 2- Stress at Fracture 2- Elongation at Fracture,The stress-strain curves of two polymers are as follows. Please show their differences based on polymer structures.,8. High performance plastics,Question: Give an example of high performance plastics that is able to withstand tempe

23、rature above 350C and explain why. PEEK: molecular structure, monomer, polymerization type, and property.,分子結(jié)構(gòu)：,單體：,逐步聚合,9. Polymer processing,Extrusion: A continuous process to produce thermoplastics in forms of band. Compression and heat molding Molding is mainly for the processing of thermosets.

24、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 reciprocating screw is used to melt a measured volume of feed. And the melt is rammed into a m

25、old 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 process are used for blow molding - injection and extrusion (thermoplastics). Calendering: Molten

26、 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 polymer, itself, or may consist of different materials. It can remain bound to the polymer used

27、after the process, or it may be removed. Spinning: dry-spinning, wet-spinning, electrospinning,Question :,Which processes are used for fabrication of the following matters: rubber gloves, plastic film, bottle, isolation sheet for cable, man-made leather, polyester fiber, air balloon, computer shell,

28、 throw-away cup, car bumper, coating, and nanofibers ?,10. Electrospinning,Question:,Please decribe the mechanism of the elelctrospinning process. Is it possible to produce nanotubes, nanocables, nanocomposites by electrospinning? How?,在靜電紡絲過程中,將聚合物熔體或溶液加上幾千至幾萬伏的高壓靜電,從而在毛細管和接地的接收裝置間產(chǎn)生一個強大的電場力。由于電場力和

29、表面張力共同作用下，液滴將被拉伸成圓錐狀（Taylor錐）。當(dāng)電場力大于表面張力時，聚合物熔體或溶液經(jīng)過噴絲板的孔眼后，在電場中被拉伸,最終在接收裝置上形成納米纖維。,11. Universal Polymer Materials,Plastics Rubber Fibers Adhesive Coatings,1) additives,1. Plastics,（一） Types lubricant, thermal stabilizer: beneficial for processing； fillers, reinforcing agent, impact modifier, plast

30、icizer: flame retardant: improve flame retardancy stabilizer: improve aging resistance,2) Universal plastic,Polyolefin plastic: PE, PP, PS (ABS, ACS),Polyamide: nylon 6, nylon 66, nylon 610, nylon 1010. Polycarbonate: Polyoxymethylene: Polysulfone P(ether ether ketone),2. Rubber,Classification: Natu

31、re rubber 聚丁二烯橡膠 聚異戊二烯橡膠 丁苯橡膠 丁腈橡膠 氯丁橡膠 丁基橡膠 Processing: What is rubber sulphuration? Please describe the main process of the rubber sulphuration.,12. Conducting polymer,Proton doping Polyacetylene: Conductivity is increased to 105 S/cm Polyaniline: 103 S/cm Doping characterization Reversibility: do

32、ping-dedoping charge-discharge,Questions,Give 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 hydrochloric acid. Give the molecular structures of three forms of polyaniline (oxidative state,

33、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 seed technique Nanofilm (2D) layer-by-layer L-B film self-assembly,Nanocomposites (Organic/inorganic hybrid materials),Nano/macro Prepare colloids in polymer solution Blend colloids with polymer solution Polymerization in inorganic p