Keywords Derive from title Multiple word “keywords” e.g. polysilsesquioxane low earth orbit Brain storm synonyms Without focus = too many unrelated hits If you haven’t already, get it to me today.

Homework Name files with your last name, and HWK# Within file, your name, HWK title, descriptive information (like the title of you paper topic) -Never make your audience work

Bibliography homework Due on 27 th at 11:59 PM Based on your keyword search J. Am. Chem. Soc. format with title e.g. Doe, J., Smith, J. “Proper bibliographies for Professor Loy’s class,” J. Obsc. Academ. B. S. 2012, 1, 234. Recommend endnote or pages or biblio.

Chapter 2 Continued Highly Crosslinked Materials Then Addition Polymerizations

Step Growth Polymers Polyesters, polyamides, engineering plastics such as polysulfones, polyetherether ketones (PEEK), polyurethanes. Condensation often occurs. Polymerization affords high MW late in the game

Step-Growth Non-Condensation Polymerization Polyurethanes 1,4-toluenediisocyanate + 1,3-propanediol [RCO 2 ] 2 SnBu 2

Functionalities > 2: Crosslinking into networks f = 3 Polyurethanes (thermoset)

Thermosets Urethanes Epoxies Polyesters (2-stage) Formaldehyde-aromatic Melamine-formaldehyde Generally: Start as low viscosity liquids (low Mw) And set or cure to form glassy “vitrified” solids.

Gelation: f > 2 If f > 2 No cyclics form then an infinite network is possible (unless it phase separates!!!)

Functionality Higher than Two Phase separation = gels, glasses, or precipitates Due to chemical bonding

Functionality = Two: Linear polymers Physical gels may form due to poor solubility of polymer

Functionality = Three: Cyclization Lowers functionality & delays (or even prevents) gelation Gel point = 1/(f -1) = 1/2 or 50% conversion If cyclics present, gel point is higher.

Addition Polymerizations 1) Catalyzed polymerization free radical cationic anionic coordination 2) Active group on end of polymer 3) MW increases more rapidly 4) Cheap & easier than step growth 5) Enthalpically favorable

Free Radical Polymerizations Initiators (catalyst): –Thermal: azo compounds, peroxides, –Redox: persulfates –Photochemical: azo, peroxides, amine/ketone mixtures Monomers

Free radical Mechanism Initiation: E a = 140 – 160 kJ mol -1 K d = 8 x s -1 t 1/2 = 10 h at 64 °C Propagation: Termination: k p = L/mol s k t = L/mol s

Free Radical Polymerization Kinetics MW TIME MOST POLYMERS FORM IN SECONDS OR LESS POLYMERIZATIONS TAKE HRS R p ∝ [M]; R p ∝ [I] 1/2

Living Radical Polymerizations: 1)Atom TransfeR Polymerization (ATRP) 2)Polymerization (RAFT) 3)TEMPO MW increases linearly with time Narrow Mw distributions Block copolymers Lower concentration of propagating species Lower termination rate

Cationic Polymerizations: Ring opening polymerization Vinyl polymerization

Anionic Polymerizations:

Coordination Polymerizations: Transition Metal Mediated Polymerizations -Ziegler Natta polymerizations (Early TM) -ring opening metathesis polymerization (metal Alkylidenes) -Insertion polymerizations (mid to late TM’s)

Ziegler Natta Polymerizations ZN are heterogeneous; solid catalysts Catalytic polymerizations Early TM halide, AlR 3 on MgCl 2 Polypropylene and HDPE Highly productive: 10 6 g polymer/gram catalyst-hour 10,000 turn overs/second (enzyme like speed)-diffusion limited Stereochemical control: Karl Ziegler ( ) Giulio Natta ( ) iso or syndiotactic polymers

Ziegler Natta Monomers Not compatible with heteroatoms (O,N,S,etc)

Polymers Synthesized with Complex Coordination Catalysts Plastics Polyethylene, high density (HDPE) Polypropylene, isotactic Polystyrene, syndiotactic Bottles, drums, pipes, sheet, film, etc. Automobile and appliance parts, rope, carpeting Specialty plastics

Ring Opening Metathesis Strained Rings with C=C bonds Metal alkylidene catalysts –Ti, Mo, W alkylidenes (Schrock catalysts) –Ruthenium alkylidenes (Grubbs catalysts) Living polymerizations

Examples of ROMP

Acyclic Diene Metathesis Polymerization Coordination-Condensation polymerization Ethylene gas is produced Not commerciallized

Redox Polymerizations Polypyrrole

Redox Polymerizations Polyaniline When acid doped: conducting polymer

Polymerization Techniques Bulk-no solvent just monomer + catalysts Solution Polymerization-in solvent Suspension-micron-millimeter spheres Emulsion-ultrasmall spheres

Less Common Polymerization Techniques Solid state polymerization –Polymerization of crystalline monomers Diacetylene crystals Gas Phase polymerization –Parylene polymerizations Plasma polymerization –Put anything in a plasma

Plasma Polymerization

Characterization of Polymers 1 H & 13 C Nuclear Magnetic Resonance spectroscopy (NMR) Infrared spectroscopy (Fourier Transform IR) Elemental or combustion analyses Molecular weight