Levente Novák & István Bányai University of Debrecen Dept. of Colloid and Environmental Chemistry

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1 Macromolecules Levente Novák & István Bányai University of Debrecen Dept. of Colloid and Environmental Chemistry

2 milliárd liter PRODUCTION OF POLYMERES AND STEEL POLYMER END OF IRON AGE ROW STEEL

3 BOEING 787 (DREAMLINER) 50% POLYMER OR POLYMER COMPOSITES 20% ALUMINIUM 15% TITANIUM 10% STEEL 5% OTHER 20% LESS FUEL CONSUMPTION

4 Macromolecules Def.: larger than 1 nm, so their properties depend on their size. Polymers are large molecules that are made from a series of monomers consists of same motives homopolymers: PE, PP, PS, rubbers (polyisoprene), PGA, pektin copolymers: proteinek, NYLON, starch natural and artificial: natural (10 6, narrow) and artificial (10 5,broad) rubbers shape: chain like (up to 1 mm) and (core-shell) secondary structures (rarely fully streched)

5 Natural macromolecules polysacharides: cellulose, chitosan (insect hard parts), pectin (plant tissue) starch (amylose, amilopectyn) polypeptides: enzymes, proteins, DNA, collagen, gelatine PGA: poly-gamma-glutamic acid COO - COO - CH CH 2 CH 2 CO NH CH CH 2 CH 2 CO NH bio-degradable

6 POLYMERS Small molecules (monomers) link to makromolecules. Monomers: Polymers: Homopolymer Random copolymer Alternating copolymer Block-copolymer HERMANN STAUDINGER NOBEL-PRIZE 1953 branching Cross linked

INDUSTRIAL Nobel-prizes Karl Ziegler Giulio Natta Paul J.

1963 was awarded jointly 1974 was awarded to Paul J.

technology of high polymers" for his fundamental achievements,

7 INDUSTRIAL Nobel-prizes Karl Ziegler Giulio Natta Paul J. Flory The Nobel Prize in Chemistry The Nobel Prize in Chemistry 1963 was awarded jointly 1974 was awarded to Paul J. "for their discoveries in the field of the Flory chemistry and technology of high polymers" for his fundamental achievements, both theoretical and experimental, in the physical chemistry of the macromolecules".

Other plastics, macromolecules+other materials PET- plastics

PP, PIB insulators Poly(methyl metacrylate): plexiglass

resin) teflon: polytetrafluoroethylene (PTFE) heat resistance, low

silicones: polydimethylsiloxane, implantates NYLON: fibers

8 Other plastics, macromolecules+other materials PET- plastics (Polyethylene terephthalate) poly-propylene and poly-izobutylén: PP, PIB insulators Poly(methyl metacrylate): plexiglass (metyl-acrylic acid metylester) bakelite (phenol-formaldehyde, PF resin) teflon: polytetrafluoroethylene (PTFE) heat resistance, low viscosity polyisoprene: natural rubber, rubber polystyrene: PS PS silicones: polydimethylsiloxane, implantates NYLON: fibers (hexamethylen diamin and hexanedioic acid condensation copolymers, 66) polyuretanes: foams bakelite

9 industrial Nobel-prizes 2. Alan J. Heeger Alan G. MacDiarmid Hideki Shirakawa The Nobel Prize in Chemistry 2000 was awarded jointly to Alan J. Heeger, Alan G. MacDiarmid and Hideki Shirakawa "for the discovery and development of conductive polymers".

10 Shape of linear polymer Polymer molecules are made up of many smaller units called monomers. A linear or slightly cross-linked polymer, above Tg. They are normally composed of a -C-C- backbone chain. The bond angle is fixed at 109.5, but the torsion angle can change, allowing the macroscopic shape of the chain to vary from being linear to being highly coiled and convoluted. extended random coil Highly coiled colloid T g glass transition temperature where the polymer goes from a hard, glass like state to a rubber like state

11 The ideal chain mathematic model for linear polymer Consider a linear polymer to be a freely-jointed chain with n subunits (segments), each of length l, that occupy zero volume, so that no part of the chain excludes another from any location. One can regard the segments of each such chain in an ensemble as performing a random walk (or "random flight") in three dimensions, limited only by the constraint that each segment must be joined to its neighbors. This is the ideal random chain mathematic model. h segments are rigid rods of a fixed length l, and their orientation is completely independent of the orientations and positions of neighbouring monomers, to the extent that two monomers can co-exist at the same place. The two ends of the polymer are marked with black rings

12 Random coils Each segment may take up any orientation with respect to its nearest neighbour, i.e. l is the length of segment then the determination of the end to end distance, <h>, is the same as for random walk. After a large number of steps the walker will on average end up exactly where he started, i.e. <h> =0, because backward (negative) steps are as likely as forward ones. However, the mean squares distance is not zero and this can be used to characterize the chain length. Which, gives the average square end-to-end distance of the ideal chain: (0 in subscript indicates the ideality) M h nl l m Where h end-to-end distance, n is the number of segments, and M and m respectively the polymer and monomer molecular weights. The random flight model should apply when each unit in the chain consists of enough chemical segments. The maximum, fully extended length L of the chain is clearly n l.

13 Random walk 2 h 1/ 2 The two ends of the polymer are marked with black rings the square root of the end-to-end distance of the configuration shown and the accumulated root mean square end-to-end distance

Comparison of different radii r m 1 1 R 2 g 1/ 2 i i mr 2 i i m i 1/ 2 1/ 2 h R g (radius of gyration) is the root mean square of mass-weighted distances of all subvolumes (segments) in a particle

14 Comparison of different radii r m 1 1 R 2 g 1/ 2 i i mr 2 i i m i 1/ 2 1/ 2 h R g (radius of gyration) is the root mean square of mass-weighted distances of all subvolumes (segments) in a particle from the center of mass. m i is the mass of the ith atom in the particle and r i is the distance from the center of mass to the ith particle. h Rg h h 2 1/ 2 the average end-to-end distance for the chain Scattering of radiation (light, neutrons, x-rays) is used to measure polymer dimensions. These methods give the radius of gyration R g. R g is the root mean square separation between all pairs of segments in a polymer molecule. For a random flight polymer 6<R g2 > = <h 2 > where <h 2 > is the average square end-to-end distance of the chain.

Comparison of different radii A comparison of the radius of gyration to other types of radii can be shown using lysozyme as an example From the crystallographic structure, lysozyme can be described

15 Comparison of different radii A comparison of the radius of gyration to other types of radii can be shown using lysozyme as an example From the crystallographic structure, lysozyme can be described as a 26 x 45 Å ellipsoid with an axial ratio of The molecular weight of the protein is 14.7 kda, The radius of gyration (Rg) is defined by the expression given before. R M is the equivalent radius of a sphere with the same mass and particle specific volume as lysozyme, R R is the radius established by rotating the protein about the geometric center h (or R 0 ) ~64 Ǻ the average end-to-end distance for the chain R H or the hydro-dynamic radius is the radius of a hypothetical hard sphere that diffuses with the same speed as the particle under examination., which includes both solvent (hydro) and shape (dynamic) effects. The hydrodynamic radius (R H ) is then calculated from the diffusion coefficient using the Stokes-Einstein equation, see later Lysozyme or N-acetylmuramide glycanhydrolase enzyme can be found in egg white

16 Kinetic phenomena. Determination of distribution of molar mass or size of polymers Brownian-motion Diffusion (see Physical chemistry) Osmosis Sedimentation Light scattering

17 Brown-motion Robert Brown ( ) First observed in 1827 by the botanist Robert Brown. He only observed pollen grains under a microscope Albert Einstein ( ) 1905: the mathematical theory of Brownian motion was developed by Einstein. A suspended particle is constantly and randomly bombarded from all sides by molecules of the liquid. If the particle is very small, the hits it takes from one side will be stronger than the bumps from other side, causing it to jump. These small random jumps are what make up Brownian motion.

18 k Mathematics of Brown-motion 1 dx Ekin m kbt 2 dt B 1, JK Thermal (kinetic) energy provides the continuous spontaneous motion, the displacement of a Brownian particle is not proportional to the elapsed time, but rather to its square root x 2 D 1/ 2 1/ 2 m s 2Dt 2-1 kt kt RT D f 6 a 6 an A average distance (random walk) D diffusion coefficient a (=R H ) hydrodynamic radius the diffusion constant can be determined from physically measurable quantities, such as the mean square displacement of a particle in a given time interval. Einstein-Stokes equation

19 Kinetic phenomena. Determination of distribution of molar mass or size of polymers Brownian-motion Diffusion (see Physical chemistry) Osmosis Sedimentation Light scattering Viscosity (next lecture)

20 Osmosis Osmosis is the spontaneous net movement of water across a semipermeable membrane from a region of high chemical potential of solvent to an area of low one, up a solute concentration gradient. In general, these membranes are impermeable to organic solutes with large molecules, such as polysaccharides, while permeable to water and small, uncharged solutes.

Osmotic pressure: P Colligative property If you place two solutions of different concentration side by side, keeping them separated only by means of a

It is possible to reverse the process and cause the solvent to pass to the less concentrated solution.

21 Osmotic pressure: P Colligative property If you place two solutions of different concentration side by side, keeping them separated only by means of a membrane, you will see the level of the more concentrated solution increase, because the two solutions try to attain the same concentration by diffusion. It is possible to reverse the process and cause the solvent to pass to the less concentrated solution. This is the process of the reverse osmosis or ultra filtration. It is used also to purify water, to concentrate solutions, etc. Osmosis is the tendency of the system to reach the same concentration in both solutions.

22 Determination of molar mass by osmosis P crt ideal case c=(m/m)/v P P crt (1 Bc...) real case (viriál) 1 M 2 crt B2c B3c... P osmotic pressure, c concentration, M molar mass, which is measurable between Number average <M>=1/NN i M i c 0 /(g/l) h/cm h/c 0 0,28 0,28 0,71 0,36 2,01 0,503 5,1 0,73 8,0 0,889 h RT Bc 1 c0 gm M RT 1 M g 0, kg mol kg mol 120 kda h height of column density, g gravitanional acceleration number avergaed

Sedimentation v h / t 9 2 9 r 2 h 2 r Stk 2 0 gt 0 g 1.

23 Sedimentation v h / t r 2 h 2 r Stk 2 0 gt 0 g 1.00 r 9 h 2( ) gt 0 W (r).75 dw /dr r, micron See Manual of Practice course

24 Ultracentrifuge M w 2RT r r b ln c c 2 1 Equilibrium method: concentration distribution 24

25 Dialysis, purification (ozmosis) 11. előadás

The Donnan membrane equilibrium 1 2 Pr - negatively charge colloid

K+ =b-y Cl - =b-y Initial concentrations equilibrium concentrations

a y y ( b y) Animation: y 2 b a 2b Large ions hinder the diffusion of

26 The Donnan membrane equilibrium 1 2 Pr - negatively charge colloid particles 1 2 K + =a K+ =b Pr - = a Cl - =b K + =a+y Pr - = a Cl - =y K+ =b-y Cl - =b-y Initial concentrations equilibrium concentrations Electro neutrality At equilibrium, the rates of diffusion are equal 2 a y y ( b y) Animation: y 2 b a 2b Large ions hinder the diffusion of small ions. E D RT ZF K ln K 1 2

Donnan membrane equilibrium and sedimentation The electric field generated in the sedimentation or centrifugation of charged colloidal particles could be exploited to determine the charge and the

27 Donnan membrane equilibrium and sedimentation The electric field generated in the sedimentation or centrifugation of charged colloidal particles could be exploited to determine the charge and the mass of macromolecules in a single experiment The electric potential arising between two solutions is called the Donnan potential. The presence of a charged impermeant ion (for example, a protein) on one side of a membrane will result in an asymmetric distribution of permeant charged ions, and it will generate a DL on the two sides of membrane.

28 Dynamic light scattering When in solution, macromolecules are buffeted by the solvent molecules. This leads to a random motion of the molecules called Brownian motion. For example, consider this movie of 2 micrometer diameter particles in pure water. As can be seen, each particle is constantly moving, and its motion is uncorrelated with the other particles. (Movie courtesy of Dr. Eric R. Weeks, Physics Department, Emory University.) As light scatters from the moving macromolecules, this motion imparts a randomness to the phase of the scattered light, such that when the scattered light from two or more particles is added together, there will be a changing destructive or constructive interference. This leads to time-dependent fluctuations in the intensity of the scattered light. In Dynamic Light Scattering (DLS), a.k.a. Quasi-Elastic Light Scattering (QELS), the time-dependent fluctuations in the scattered light are measured by a fast photon counter. The fluctuations are directly related to the rate of diffusion of the molecule through the solvent, which is related in turn to the particles hydrodynamic radii. DLS is employed by the DynaPro NanoStar, the DynaPro Plate Reader II, the Mobius and the WyattQELS Dynamic Light Scattering Module for MALS detectors to determine the effective particle size. Q&list=PLqTc0zgsaR7uXs9HFDJyEKXCPjvneQviv

PSt-b-PIB-b-PSt TRIBLOCK COPOLYMER DRUG-ELUTING CORONARY STENT COATING: A REVOLUTION IN CARDIOLOGY FDA approved in 2003; marketed by Boston Scientific Co.

29 PSt-b-PIB-b-PSt TRIBLOCK COPOLYMER DRUG-ELUTING CORONARY STENT COATING: A REVOLUTION IN CARDIOLOGY FDA approved in 2003; marketed by Boston Scientific Co. (first year led to ~$3 billion income in sales) Number of bypass surgeries reduced by ~85% Stainless-steel stent with PSt-PIB-PSt coating: coating is coherent, undamaged post-expansion

Macromolecular colloids. Size and shape of linear macromolecules. Osmosis and osmotic pressure.

Macromolecular colloids. Size and shape of linear macromolecules. Osmosis and osmotic pressure. What are macromolecules Macromolecules (macro = large, big) are large molecules Larger in solution than 1