1、Polymer Physics高分子物理,2 Aggregate Structure of Polymers 高分子聚集态的结构,2.1 Introduction,引言,2.1.1 Concept of aggregate state 聚集态结构的内涵,Aggregaste state Arrangement and stacking of different polymer chains.Aggregaste state includes 晶态 Crystalline state 液晶态 Liquid crystalline state 非晶态 Amorphous state 取向态 Ori
2、entation state,2.1.2 Interactions between polymer molecules 高分子的分子间作用力,covalent bond interactionnon-covalent bondvan de Walls forceH bond,高分子由于分子间的相互作用而堆砌在一起,Electrostatic force(静电力):1.21042.1104 J/molInduction force(诱导力)： 0.61041.2104 J/molDispersion force(色散力)： 0.081040.84104 J/mol,偶极矩,极化率,电离能,分子间
3、距离,van de Walls force,Total van de Walls force: 28 kJ/molCC bond energy: 347 kJ/mol,Assuming：PEs DP=104 ，Intermolecular interaction force: Ef 2*104 kJ/molCC bond energy: EJ=347 kJ/molEfEJWhen a single PE chain is pull out, 2*104kJ/mol energy (van de Walls force) must be overcome，which can lead to br
4、eakage of C-C single bond.So, no vapor state for polymer.,Interaction force between the H atom in XH bond and another Y atom with large electronegavity. Electronegativity：H:2.1 O:3.5 N:3.0 F:4.0 Strength：1535 kJ/mol Features：directivity and saturabilityXHY,Hydrogen bond 氢键,2.1.3 Cohesive energy dens
5、ity 高分子的内聚能密度,Cohesive energy ：The energy to remove 1 mol liquid or solid molecules out of the range of intermolecular interaction force.,HV: 摩尔蒸发热,Cohesive energy density： Cohesive energy in unit volume.,HS:摩尔升华热,( : 摩尔体积),Cohesive energy density of linear polymers,Rubber,Plastics,Fiber,2.2 The Cry
6、stalline State,高分子的晶态结构,Difference bewteen crystallization of polymers and small molecules:Polymer is not 100% crystalline!crystallinity (结晶度)：faction of crystalline phaseweight percentage crystallinityvolume percentage crystallinity,1a,2a,2b,3a,3c,A,B,C,AB + BC = 2dsinq,2dsinq = nl,2.2.1 Methods of
7、 determining crystallinity,wide angle X-ray diffraction (WAXD) X衍射,Bragg equation,Distance between successive identical planes of atoms in the crystal,X-ray wavelength,Angle between the x-ray beam and these atomic planes,Any whole number,样品,差式扫描量热法 (DSC) Differential scanning calorimetry,(Xcw%),(i)
8、Xcv,Measured by density,(ii) Xcw,Determination of Density,Ni: number of ith atom in unit cell Ai: atom mass of ith atom in unit cell Ve : volume of unit cell NA: Avgadrov constant,c is calculated from the densityof unit cell of polymer crystal：,Notice：The values of crystallinity measured by differen
9、t methods may have a large difference.Usually：XcWAXD () Xcdensity XcDSC,2.2.2 Unit cell and conformation of polymer chain in crystals,spherulite fibrillar branching helical lamellae within fibrils 1 mm(POM) 1 m(AFM) 500 (AFM, TEM),crystal lattice individual lamellar stacks1 (WAXD) 100 (SAXS),Princip
10、le types of crystal system,a,b,c,高分子无此晶系,c axis:polymer chain direction,Unit cell (晶胞)：The smallest repeating unit of crystal structure with parallelepiped shape,Miller indices (h k l),(1) intercept of crystalline plane in axes,(2) removal of unit，getting reciprocal and reduction to common denominat
11、or,(3) removal of denominator,a=2d200,Selected crystallographic data,For polymer chains with no side group (PE) or with side group of small size (polyester，polyamide，POM，PVA). Polymer chains adopt all-trans conformation. The lowest energy of polymer chains. Advantageous to dense packing in crystals.
12、,plane zigzag(平面锯齿结构),PE Orthorhombic正交晶系,Unit cell of PE: Orthorhombic, a=7.417, b=4.945, c=2.547Number of C and H atoms in unit cell？Ve 9210-24 cm3; NA = 6.0231023 mol-1c 1.01 g/cm3,The hydrogen-bonded structure of nylon 66. The unit cell face is shown dotted,Helix(螺旋形结构),For polymer chains with s
13、ide group of large size, gauche conformation sometimes is adopted to reduce steric hinderance and free energy. For example：isotactic PP(H31),poly(o-methyl styrene)(H41),isotactic PMMA(H52)，isotactic poly(4-methyl pentene-1) (H72),poly(m-methyl styrene)( H11 8).,Isotactic PPThe polymer chains are not
14、 in the same plane, but exhibit a helix conformation in the three-dimensioal space. Every three repeating units forms a helix with a periodic length l6.50. H31: H：Helix3：number of repeating units1：number of turns within a period,iPP(等规聚丙烯)：Monoclinic 单斜,2.2.3 Models of crystalline polymers高分子晶态结构模型,
15、The Fringed Micelle Model 缨状微束,Crystalline phase,Amorphous phase,100,Contour length = 2000,Bryant 1940,Atactic PP,Isotactic PP,Al,Observation：Both diffraction pattren and diffused circle are observed. The measured size of crystalline domain is about hundred astrongs (much smallerthan the length of p
16、olymer chain) Model： cocurrence of crystalline and amorphous domainssmall size of crystalline domain (one polymer chain cantraverse several crystalline domains)random orientation of crystalline domains Reasonable：The apparent density density of unit cellmelting range due to different sizes of crysta
17、lline domains Arc diffraction pattern and birefringence after tensile drawing Unreasonable：Crystalline and amorphous domains can separate.How lamellar and spherulitic morphology formed?,The Folded Chain Model 折叠链,Crystalline phase,Amorphous phase,Keller 1957,110140,Single crystals,近邻折叠,Observations:
18、PE single crystals with tens of micrometers size and 100 thickness (TEM).Thickness of single crystal is independent of Mw.Polymer chains are perpendicular to the lamellae (XRD) Model： Polymer chains regularly fold and form lamellar crystals of 100 thickness, which can stack into fibril stacks and th
19、en spherulites. Reasonable：Formation of lamellar and spherulitic morphology Unreasonable：The density of surface is smaller than the bulk of single crystals,规则近邻折叠,近邻松散折叠,Can explain why the density of surface is smaller than the bulk of single crystals. Unreasonable：Crysyallization of some polymer t
20、akes place very fast(such as PE). Regular folding is difficult to reach since it is a relaxation process.,The Switchboard Model 插线板,Crystalline phase,Amorphous phase,Flory,Crystals from melt,小角中子散射(SANS)测量聚合物的分子尺寸,近邻折叠,插线板模型,熔体,Observation：The gyration radius of PE chains in crystal is similar to th
21、at in the melt.In the crystals polymer chains bascially retain the conformation in the melt, but locally adjusted to enter the crystals.Model： Amorphous domains on the surface of lamellae. The adjacent polymer chain segments in the crystals can be from the same (but non-adjacent segments) or differe
22、nt polymer chains.After the polymer chain enter a lamellar crystal, it can traverse into another crystal or re-enter the same crystal at non-adjacent position.,Regularity of the modelsadjacent re-entry model switchboard model fringed micelle modelEffect of crystallization conditionsfrom dilute solut
23、ion： 100% adjacent re-entryfrom melt： 70% adjacent re-entryquench： fringed micelleEffect of polymer microstructurehomopolymer： adjacent re-entry or switchboardrandom copolymer：fringed micelle,2.2.4 Morphology of polymer crystals 高分子晶体的形态,Lamellar-shaped single crystals 单晶,聚乙烯的空心棱锥结构,Formation of pol
24、ymer single crystalCrystallize very slowly from extremely dilute solution (0.010.1%) (but sometimes can also be formed from the melt),Dendritic crystal(树枝状晶),Higher concentration(0.010.1%)，lower Tc. Diffusion controlled.,PE,PEO,Extended Chain Crystals 伸直链晶体,Polyethylene 226C, 4800atm, 8hr Crystallin
25、ity = 97% Density = 0.9938,30000,High pressure and high temperature.,The most stable in thermodynamic.,Fibril Crystals 纤维状晶体,In flow field, polymer chains extend and stack along flow direction.,String Crystals 串晶,溶液低温，边结晶边搅拌。,shish-kebab structure,spherulite(球晶),Polarized optical microscopy (偏光显微镜),
26、Maltese Cross,Branching,spherulite of iPP,Spherulite,Febrile,Lamellar,晶迭的形成,a amorphous c crystalline L long period,Negative spherulite：radial refractive index normal refractive index (small branching angle),Constant growth rate in radial direction Polymer chain perpendicular to radius Maltese cross
27、 by POM Consisting in fibrils and stacks Crystallinity 100% Diameter from 0.1mm to 1cm,Characteristics of spherulite,Control of spherulite size,(1) Crystallization rate: Tc or cooling rate (2) Microstructure: random copolymer (3) Nucleation agent: smaller size,Having effects on transparency and mech
28、anical properties,Growth of spherulite observed by POM,banded spherulite(条带状球晶),电镜观察的球晶结构,Spherulite model and the Microscopy of PE spherulite 球晶模型及PE球晶的电镜照片,small angle laser light scattering 小角激光散射,Radius of spherulite,Wave length,Scattering angle corresponding to maximum scattering intensity,axia
29、lite,platelet,2.3 Amorphous state,无定型态结构,2.3.1 About amorphous polymers 关于无定型高分子,The amorphous state is defined as a condensed, noncrystalline state of matter. Many polymers are amorphous under ordinary use conditions Polystyrene Poly(methyl methacrylate) Poly(vinyl acetate) Crystalline polymers bec
30、ome amorphous above their melting temperatures Polyethylene Polypropylene Nylon,Glassy,Liquid flow,Rubbery plateau,Glass transition,Rubbery flow,lgE, Pa,Temperature,Tm,6,5,7,4,3,8,9,10,Amorphous polymers,Crystalline polymers,Physical state of polymers 高分子的物理状态,From amorphous phase,Questions of inter
31、est 感兴趣的问题,Solids or liquid? Water: liquid, disordered Crystalline polymer: solid, ordered (regular) Amorphous polymer in glassy state: solid, disordered,Possible residual order? On the simplest level, the structure of bulk amorphous polymers has been likened to a pot of spaghetti, where the spaghet
32、ti strands weave randomly in and out among each other Our knowledge of the amorphous state remains very incomplete, and that this and other areas of polymer science are the subjects of intensive research at this time,2.3.2 Major order-disorder arguments 有序无序之争,2.3.3 Models of amorphous polymers 无定型高
33、分子模型,Models of the amorphous state in pictorial form 无定型高分子模型图示,Models increase in degree of order from (a) to (d).,Florys random coil model 无规线团,Privalko and Lipatovs randomly folded chain conformations 无规折叠链,Yehs folded-chain fringed-micellar model 折叠链缨状微束,Pechholds meander model 回纹波,Evidences for
34、 random coil modelAbsebce of anomalous effects for rubber elastic modulus and stress-temperature parameter when diluent is added. When radiate amouphous polymer in bulk and solution, the crosslinking degree is similar. The gyration radius in bulk and solution is similar (by SAXS and SANS),Evidences
35、for fringed micellar modelFor random coil: a/c0.65, in practice: a/c0.85-0.96.Ordered stacking is preparative for fast crystallization.After thermal treatment, density and size of micelles increases.Whitening upon tensile for rubber.,2.4 Orientational state,取向态结构,2.4.1 Orientation Phenomena 取向现象,Pre
36、ferred arrangement of polymer chain, segment or crystalline domain under external force in some specific directions (分子链、链段、晶粒等在外力作用下沿特定方向作占优势的排列),A special phenomena in polymeric materials,Orientation state one- or two-dimensionalCrystalline state three-dimensional order,processing,film (biaxial dr
37、awing or blowing),fiber (drawing),pipes and rods (injection),amorphous,oreintated amorphous,crystalline un-orientated,crystalline orientated,聚合物的取向一般有两种方式： 单轴取向(uniaxial orientation)：在一个轴向上施以外力，使分子链沿一个方向取向。如纤维纺丝,再如薄膜的单轴拉伸,双轴取向(biaxial orientation)：一般在两个垂直方向施加外力。如薄膜双轴拉伸，使分子链取向平行薄膜平面的任意方向。在薄膜平面的各方向的性能
38、相近，但薄膜平面与平面之间易剥离。,薄膜的双轴拉伸取向,2.4.2 Orientation Mechanism 取向机理,链段取向,整链取向,球晶取向 与变形,晶区取向 与重组,可在高弹态实现,只能在粘流态实现,取向单元,无定形聚合物 Amorphous polymer,晶态聚合物 Crystalline polymer,链段取向,非晶区 Amorphous region,晶区 Crystal region,链段取向,球晶变形，晶片 倾斜、滑移、取向,取向与解 取向问题,聚合物可以取向，但取向是一种热力学不稳定状态，在一定的外力、时间、温度下又有解取向。,整链取向,整链取向,为了维持取向状态，
39、获得取向材料，必须在取向后迅速使温度降低到玻璃化温度以下，使分子和链段“冻结”起来，这种“冻结”仍然是热力学非平衡态。只有相对稳定性，时间长了，温度升高或被溶剂溶胀时，仍然有发生自发的解取向性。取向快，解取向也快，所以链段解取向比分子链解取向先发生。,2.4.3 Methods to Determine the Degree of Orientation 取向度的测量方法,取向（程）度的表示 拉伸比拉伸前后长度之比取向函数 F为分子链主链与取向方向间的夹角 理想单轴取向： = 0 cos =1 F=1完全无规取向：F= 0,Sound velocity method 声速法,Wide-angl
40、e X-ray diffraction 广角X射线衍射法,Birefringence anisotropic method 双折射法,Infrared Dichroism 红外二向色性,测量方法,WAXD,取向参数,(A: 半峰宽),Question:Can 1D WAXD be used to determine crystallinity of orientated polymer samples?,声速法,原理：声速沿分子链的传播速度链间的传播速度,声波在完全未取向聚合物中的传播速度,待测聚合物取向方向上的传播速度,Birefringence anisotropic method 双折射
41、法,2.4.4 Influence of Orientation to the Properties 取向对性能的影响,Polyester fiber,* 取向方向的拉伸强度显著提高* 材料呈现各向异性的特性* 热稳定性能得到相应提高,2.5 Liquid crystal state,液晶态结构,2.5.1液晶的化学结构与分类,不论高分子还是小分子液晶，形成有序流体都必须具备一定条件，从结构上讲，称其为液晶基元 液晶基元包括棒状(条状)、盘状或双亲性分子 棒状(或条状) 长径比大于4 盘状 轴比小于1/4 双亲性分子 有特殊的相互作用力,MBBA,5CB,2.5.2 Category of l
42、iquid crystal 液晶种类,盘状液晶 Discotic,Discotic Nematic DN,Discotic hexagonal ordered Dho,Discotic hexagonal disordered Dhd,按液晶基元所在位置分类,主链型液晶,侧链型液晶,按液晶形成条件分类,热致液晶：通过加热而形成液晶态的物质 - 共聚酯， 聚芳酯Xydar, Vector, Rodrum,溶致液晶：在某一温度下，因加入溶剂而呈现液晶态的物质 - 核酸，蛋白质，芳族聚酰胺PBT, PPTA (Kevlar) 和聚芳杂环PBZT, PBO,感应液晶：外场（力，电，磁，光等）作用下进入
43、液晶态的物质 - PE under high pressure,流致液晶：通过施加流动场而形成液晶态的物质 -聚对苯二甲酰对氨基苯甲酰肼,结构,液晶包括高分子液晶和小分子液晶。不论高分子还是小分子，形成有序流体都必须具备一定条件，从结构上讲，称其为液晶基元。,液晶基元,棒状(或条状) 长径比大于4,双亲性分子,盘状 轴比小于1/4,分类,按液晶核的排列分,按液晶基元 所在位置分,按液晶的形成条件分,棒状,盘状,向列相N：只有方向序无位置序,近晶A相SA：有位置序和方向序,近晶C相SC：有位置序和方向序且既有层面的法向方向又有晶核的共分方向,柱相,向列相 (Discotic N) DN,有序程度
44、SCSAN,如果层内间隔相等 Dho,如果层内间隔不等 Dhd,主链液晶,主侧链液晶,侧链液晶,热致液晶：液晶物质加热熔融形成的液晶。,溶致液晶：液晶物质溶于溶剂所得到的液晶。,High rigidity Rod-like chain Strong interaction,Kevlar/芳纶14,Kevlar 49/芳纶1414,2.5.3 Properties and application of liquid crystal polymers 液晶高分子的性能和应用,Properties of some fibers 一些纤维的性能,c*,各向同性,液晶,c,T*,各向同性,液晶,T,液晶
45、纺丝,液晶原位增强聚合 液晶显示 LCD- Liquid crystal display 液晶纺丝： 在低牵伸倍数下获得高度取向、高性能纤维,液晶的应用,Crystalline stateAmorphous stateOrientation stateLiquid crystalline state,三维有序，热力学稳定,宏观无规线团，局部可能有序,一维或二维有序，由外力诱导，热力学不稳定 取向单元可以是链段，整链或晶粒,一维或二维有序，热力学稳定 取向单元是液晶基元,2.6 Structure of Multicomponent Polymers,多组分聚合物的结构,2.6.1 Concep
46、t of multicomponent polymers 多组分聚合物的概念,Definition 含两种或两种以上高分子链的复合体系，其一种或几种主要性能明显优于单一组分 Nomenclature Multi-component Polymers 多组分聚合物 Multi-phase Polymers 多相聚合物 Polymer Blend 高分子共混物 Polymer Alloy 高分子合金,Why multicomponent polymers？ 为什么要发展多组分聚合物,Relatively few new polymers will be introduced commerciall
47、y in the future because of unfavorable economics： Requires new monomers Requires change in current polymer synthesis process Requires compliance with government premanufacturing regulations Requires years before profitability Potential advantages of blending known polymers to produce new products Lo
48、wer cost of development and lower capital investment Shortened time for testing and approval when work from known property data base of blended polymers Blend preparation may be done in extrusion equipment Potential for use of recycled polymers,Some commercial polymer blends,2.6.2 Category of multic
49、omponent polymers 多组分聚合物的品种,Blend 物理共混物 熔融共混、溶液共混 Block copolymer 嵌段共聚物 活性阴离子聚合 Graft copolymer 接枝共聚物 自由基聚合 Interpenetrated Polymer Network 互贯聚合物网络 分别聚合,高分子材料,均聚物,聚合物基复合材料,共混物,共聚物,交替共聚物,接枝共聚物,嵌段共聚物,无规共聚物,熔融共混物,胶乳共混物,溶液共混物,互穿聚合物网络,多组分聚合物,均相结构 两组分相容 单相连续结构 一相为连续相，形成基质（matrix） 一相为分散相，为颗粒状（domain）、棒状、蜂窝状等 两相连续结构 两相连续并互相贯穿，多见于IPN 两相互锁结构 两相互相交错，但均没有贯穿整个体系,
