Physics and Chemistry of ybrid rganic- Inorganic aterials Lecture 12: Polymerizing inorganic monomers dissolved in organic polymers
Key concepts Reasons for making an inorganic filled organic polymer hybrid: improve strength, abrasion resistance, modulus, hardness, inflammability, etal oxide inorganic paricles can be made by sol- gel, flame synthesis rganic phase: organic polymers Inorganic paricles increase viscosity ParIcle aggregaion ruins hybrid effects smaller the paricle, the greater the strength and modulus of the hybrid the higher the paricle concentraion, the greater the strength and modulus of the hybrid
aking ybrid aterials: Class 1B (in situ paricle growth) (R') x R' R' R' R' R R' R' R' R' R' R' R R' R' R' Ideally, no Solvent except for monomer(s) No solvent with low t g organic polymers or in polymer melts (< 100 C) or if monomer will is soluble in polymer. therwise solvent may be used to mix before casting.
PreparaIon by dissolving inorganic monomer in solid organic polymer then polymerizing to form paricles Solid rganic Polymer Inorganic onomer (liquid) & catalyst Polymerization by: 1) hydrolysis & condensation of (R) n Water diffuses into membrane from air 2) Reduction of metal compound. 2 or polymer itself as reducing agent 3) sulfidation of cations ( 2 S) 4) photochemical or thermal decomposition rganic Polymer Inorganic onomer onomer must be soluble in polymer onomer polymerizes & forms particles
PreparaIon by mixing inorganic monomer with liquid organic polymer & hydrolysis & condensaion Liquid rganic Polymer Inorganic onomer (liquid) & catalyst Physical mixing Very few liquid polymers, save some elastomers like polydimethylsiloxane and low molecular weight polybutadiene or polyisoprene rganic Polymer Inorganic onomer 1) Water diffuses in from outside 2) onomer polymerizes 3) Particles phase separate lica-ps materials are looked at later in lecture
PreparaIon by mixing inorganic monomer with solid organic polymer and allowing paricles to form Solid rganic Polymer Dissolve rganic Polymer in solvent Inorganic onomer (liquid) Physical mixing Solvent must be removed before polymerization Water for hydrolysis and condensation would be diffused into dry film from air. rganic Polymer Inorganic onomer in solvent rganic Polymer Inorganic onomer Evaporate solvent onomer polymerizes & forms particles Spherical particles lica-nafion materialsmade this way are looked at later in lecture
Polymers used Elastomers: silicone, polybutadiene, polyisoprene ThermoplasIcs: polyurethanes, polycarbonates, polyvinylalcohol, polyacrylates, polysulfones, polyethylene oxide (PE), polypropylene oxide (PP) Thermosets: epoxies Polyionomers: Nafion
Review of polymerizaions 1) hydrolysis & condensa>on of (R) n or R(R ) 3 2) Reduc>on of metal compound 3) sulfida>on of ca>ons 4) photochemical or thermal decomposi>on
ydrolysis & condensaion of (R) n : the monomers licon: (R) 4 or R (R) 3 Aluminum: Al(R) 3 or AlCl 3 6 2 Transition metals: z (R) n or z Cl n h 2 z = oxidation number for metal n = number of alkoxide or halide in monomer h = number of coordinating waters
ydrolysis & condensaion of (R) 4 ydrolysis R R R R 2 R R R R Condensation R R R R R R R R R R R R Water from Condensation ydrolyzes Additional R R R R R 2 R R R R Net Reaction R R R 2 2 R n Catalyzed by acids (Cl,N 3 ) or bases (N 3 aq, Na) or fluoride. 2
ParIcles from hydrolysis & condensaion of (R) 4 Typically leads to amorphous spherical particles (not quartz) Can template particles with ordered mesopores with surfactants Stober synthesis from TES with N 3 and water gives monodisperse particles Emulsion polymerization (water in oil) gives monodisperse particles ther preps give polydisperse particles
ydrolysis & condensaion of R(R) 3 ydrolysis R R' R' Condensation R' R' R' R' R' R + R R R + water producing R' R' R' R' R R R R' R R' R R R R' R R R R R R R' R' R' R' R' R' R R R Intramolecular condensation DImerization of two tetramers to give T8 or cyclization R' + ' R + R' R' R R' R R' R' R R R' + R R R R' R R' R' R R' R' R R R' R' R Branching R' n R R' + 1.5n 2 [R 1.5 ] n + 3n R' R' Net reaction
ParIcles from hydrolysis & condensaion of R(R) 3 Typically leads to amorphous spherical particles Not as easy to prepare particles as with silica Can template particles with ordered mesopores with surfactants Stober synthesis from TES with N 3 and water affords polydisperse particles Emulsion polymerization (two step) gives monodisperse particles
ydrolysis & CondensaIon of z (R) n to = Al, B, Ti, Zr, Cr, Fe.. form n/2 ydrolysis: formation of monomeric species (R) n + n 2 () n + x R in reality: z () n z 2 2 R 2 R Condensation: formation of oxo (neutral) -- R oxidation state increases higher charge & higher p ore reactive, but too high shuts down condensation
ydrolysis & CondensaIon of z (R) n to form n/2 lation: formation of oxo (neutral) -- 2 2 2 2 2 olation >> oxolation
ParIcles from hydrolysis & condensaion of (R) n Particles may be amorphous or crystalline Some amorphous particles will crystallize with time. Stober synthesis from TES with N 3 and water does not work Emulsion polymerization (water in oil) gives monodisperse particles any more molecular clusters are available through olation chemistry
ReducIon of metals Ag + N 2 4 Ag Langmuir, 2012, 28 (11), pp 4974 4983 Ag +, Pd 2+ hν hydroquinone Ag, Pd Ag +, Pt 2+, Au 2+ e n Ag, Pt, Au acromole. Rapid Comm. 2009, 30, 1116 Pt 2+ 1 and 2 R Pt Soft Nanoscience Letters, 2012, 2, 34-40 (C) n hν or heat or ultrasound Zeitschrift für Physikalische Chemie 217, 11,1361-1368
etal and SemiconducIng Sulfides z+ 2 S S x z+ S S x J. Am. Chem. Soc., 2003, 125 (36), pp 11100 11105 RN 2 S z+ N S - Na+ eat S x CrystEngComm, 2011, 13, 4572-4579
in situ lica- Nafion Nanocomposite Solid Nafion Dissolve Nafion in Ethanol (Et) 4 (liquid) Physical mixing Nafion & TES in ethanol Evaporate solvent Nafion T Nafion & TES lica particles form in membrane Spherical particles
in situ lica- Nafion Nanocomposite Class 1A Class 1B 5 weight percent ex situ silica in Nafion In situ lica particles
In situ filled lica in polydimethylsiloxanes Solid rganic Polymer Inorganic onomer (liquid) & catalyst e e n + x e e e e rganic Polymer Inorganic onomer Sn or Ti Catalyst -4x e [ 2 ] x e e n Spherical particles Journal of Polymer Science Part B: Polymer Physics, 2003, 41, 16
In situ filled lica in polydimethylsiloxanes e e n + x e e e e Sn or Ti Catalyst -4x e ighly transparent Does not require mechanical blending [ 2 ] x e e n Journal of Polymer Science Part B: Polymer Physics, 2003, 41, 16
In situ filled lica in polydimethylsiloxanes e e n + x e e e e Sn or Ti Catalyst -4x e [ 2 ] x e e n Journal of Polymer Science Part B: Polymer Physics, 2003, 41, 16
lver paricles made in situ polydimethylsiloxanes e e n Ag + e n Ag in e e n
PE PP PE ydrophilic ydrophilic ydrophobic Templating with triblock copolymer is formally a Class 1B material Polymer is template. After removal, silica remains
Summary: In situ formaion of inorganic phases in polymers ethod for mixing at nanoscale without mechanical blending required- less chance for aggregaion and segregaion to occur (steric stabilizaion) Raises modulus and strength of materials In situ polymerizaion of inorganics selecively in blocks of block copolymers- first step to biomimeic mineralizaion.