Silica-Like Malleable Materials Group 10 Kristen Losensky Tzu-Hao Yen 11-16-12

Summary: How It Works Thermoplastics Flow when heated Can be extruded shaped and molded Thermosetting / Cross-linked Polymers Can not be reprocessed by heat or solvent Dimensional stability High-temperature mechanical, thermal, and environmental resistance Make covalent links reversible High Temperature: exchange reactions enable stress relaxation and malleability Low Temperature: exchanges become essentially stop, producing a solid system Reversible topology fixing controlled by kinetics Preserve Network Integrity/Total # of Links/ Avg Functionality of X-Links/ Does not require Depolymerization Montarnal, Damien, Mathieu Capelot, Francois Tournilhac, and Ludwik Leibler. "Silica-Like Malleable Materials from Permanent Organic Networks." Science 334 (2011): 965-68. Web. 11 Nov. 2012.

Summary: Research Performed Synthesis of both hard and soft epoxy networks with rearrangable topology Exchange reactions without depolymerization. Insoluble and processable Gradual viscosity variations Examination of thermal and mechanical properties

Thermosetting Polymers Thermosetting materials Irreversible Liquid prior to curing Good mechanical properties Solvent resistant Cured by heat and radiation Example = Bakelite  suitable for electrical industries because of its resistance to heat and chemical reaction, used for non-conducting parts, also used for wire insulation, brake pads. http://sp.life123.com/bm.pix/how-to-change-brake-pads.s600x600.jpg

Cross-Linked Materials Cross-linking Un-polymerized resin + Crosslinking agents Difficult to break Most materials when heated may degrade or burn Commercial plastics http://chemistry2.csudh.edu/rpendarvis/thermoplas.GIF

Thermoplastic Polymers Thermoplastic materials Reversible Remold and reforms Weaker mechanical properties Solvent soluble Recyclable Acrylontrile butadiene styrene = lego blocks Polycarbonate = eyeglass lenses http://images.wisegeek.com/stack-of-legos.jpg http://chemistry2.csudh.edu/rpendarvis/thermoplas.GIF

Reversible Malleable Material Issues Depolymerization-repolymerization equilibria Degradation of combined materials Unavoidable termination reactions http://images.clipartof.com/small/1047648-Royalty-Free-RF-Clip-Art-Illustration-Of-A-Cartoon-Black-And-White-Outline-Design-Of-A-Man-Carrying-A-Heavy-Problem-Rock.jpg

High Silica Materials Amorphous silica Thermally insulated Inert to chemical reagents Resistance to organic acids Electrical insulation Easily molded http://www.argosyinternational.com/datasheet/Thermal%20Management%20Systems-High%20Silica%2010.14.08.pdf http://image.made-in-china.com/2f0j00zBQTMaICHFcK/High-Purity-Silicon-Dioxide-Coating-Material.jpg

Stress & Strain Diagram Will explain each point during presentation

Previous Work Radical Systems Chemical Equilibrium Photoinduced plasticity in cross-linked polymers Thermally/ Photochemically induced reparability Unavoidable Termination Reactions Chemical Equilibrium Heating Drives equilibrium towards depolymerization Increases rate of bond breaking/reforming Prevent flow by using glass transition Increased fluidity and processability Network is less stable and sensitive to solvents (Undesirable Termination Limits reversibility) (Solvents displace equilibrium) molle.k.u-tokyo.ac.jp

Materials and Methods Soft Networks Fatty acids and Catalyst Zn(Ac)2, 2H2O heated from 100 °C to 180°C under vacuum Diglycidal ether of bisphenol A (DGEBA) is added to fatty acid mixture and stirred at 130°C Mixture is poured into brass mold with anti-adhesive silicone paper COOH : epoxy is 1:1 http://chemsrv1.uwsp.edu/macrog/lab/epoxyqc.htm

Materials and Methods Hard Networks Zinc Acetylacetonate Dihydrate Catalyst dissolved in DGEBA by heating Glutaric Anhydride added Poured into brass mold Cured at 140°C for 12 h http://www.sigmaaldrich.com/catalog/product/FLUKA/49670?lang=en&region=US

Results: Soft Network Synthesis DGEBA and fatty dicarboxylic and tricarboxylic acids Epoxy/COOH has 1:1 stoichiometry Zinc Acetate Catalyst Zn(Ac)2 Complete conversion of epoxy groups Transesterification Reactions Want both OH and Ester groups in final material -> Exchange reactions = transesterification reactions Montarnal, Damien, Mathieu Capelot, Francois Tournilhac, and Ludwik Leibler. "Silica-Like Malleable Materials from Permanent Organic Networks." Science 334 (2011): 965-68. Web. 11 Nov. 2012.

Results: Soft Network Properties Elastomeric behavior Modulus of 4 MPa Elongation and stress at break 180%, 9 MPa Number of ester links does not change with heating Montarnal, Damien, Mathieu Capelot, Francois Tournilhac, and Ludwik Leibler. "Silica-Like Malleable Materials from Permanent Organic Networks." Science 334 (2011): 965-68. Web. 11 Nov. 2012.

Results: Soft Network Solubility The network swells but does not dissolve Fig. 2 Flow and insolubility properties of an epoxy network with 5 mol% Zn(Ac)2 catalyst. (A)Swelling during immersion in trichlorobenzene Montarnal, Damien, Mathieu Capelot, Francois Tournilhac, and Ludwik Leibler. "Silica-Like Malleable Materials from Permanent Organic Networks." Science 334 (2011): 965-68. Web. 11 Nov. 2012.

Results: Soft Network Malleability Can completely relax stresses at high temperatures η(T) follows Arrhenius law 100 °C relaxation time of 58 h Room temperature relaxation time of 6 yr Can easily make complex shapes without mold (Activation Energy = 80 kJ/mol K) (B=Normalized stress relaxation at different T) b/c n does not change abruptly, do not need precise T control -> more manufacturing options Montarnal, Damien, Mathieu Capelot, Francois Tournilhac, and Ludwik Leibler. "Silica-Like Malleable Materials from Permanent Organic Networks." Science 334 (2011): 965-68. Web. 11 Nov. 2012.

Results: Hard Network Synthesis DGEBA with glutaric anhydride Zinc Acetyl Acetonate Zn(AcAc)2 Epoxy/Acyl stoichiometry is 1:1 Transesterification Reactions Resins made by Epoxy-Anhydride reactions Montarnal, Damien, Mathieu Capelot, Francois Tournilhac, and Ludwik Leibler. "Silica-Like Malleable Materials from Permanent Organic Networks." Science 334 (2011): 965-68. Web. 11 Nov. 2012.

Results: Hard Network Solubility Sample swells but does not dissolve 16 h in trichlorobenzene at 180 °C Number of ester links does not change with temperature Network does not polymerize even after a long t and at high T Montarnal, Damien, Mathieu Capelot, Francois Tournilhac, and Ludwik Leibler. "Silica-Like Malleable Materials from Permanent Organic Networks." Science 334 (2011): 965-68. Web. 11 Nov. 2012.

Results: Hard Network Properties Behavior is similar to typical hard epoxy resins Glass Transition Tg 80 °C Modulus of 1.8 GPa Stress at break of 55 MPa Transesterification reactions allow network to flow Viscosity of 1.2 x 1010 Pa s η(T) follows Arrhenius equation (200C Elongational Creep expt) (10 mol% catalyst) (deformation varies linearly w/time, n from slope) (Ea = 88 kJ/mol K) A=Tensile Test Montarnal, Damien, Mathieu Capelot, Francois Tournilhac, and Ludwik Leibler. "Silica-Like Malleable Materials from Permanent Organic Networks." Science 334 (2011): 965-68. Web. 11 Nov. 2012.

Results: Hard Network Malleability Can be reprocessed Compression molding at high temperature 3 min at 240 °C Can form complex shapes without molds Montarnal, Damien, Mathieu Capelot, Francois Tournilhac, and Ludwik Leibler. "Silica-Like Malleable Materials from Permanent Organic Networks." Science 334 (2011): 965-68. Web. 11 Nov. 2012.

Results: Topology Systems with exchangeable links behave as a viscoelastic fluid Above Tg exchange reactions occur slowly Material properties depend on thermal history During cooling ramp: Topology rearrangements become too slow, network appears quenched Further cooling freezes local monomer motion (@ highT) (polymer melts flow properties by monomer friction) (freeze monomer motion = Tg) Montarnal, Damien, Mathieu Capelot, Francois Tournilhac, and Ludwik Leibler. "Silica-Like Malleable Materials from Permanent Organic Networks." Science 334 (2011): 965-68. Web. 11 Nov. 2012.

Results: Dilatometry Experiments Cross-linked polymers have lower expansion coefficients Increasing catalyst concentration increases expansion coefficients Topology freezing is well separated from Tg Topology freezing and Tg shift to higher temperatures when the heating rate is increased (more catalyst -> faster rxns) Montarnal, Damien, Mathieu Capelot, Francois Tournilhac, and Ludwik Leibler. "Silica-Like Malleable Materials from Permanent Organic Networks." Science 334 (2011): 965-68. Web. 11 Nov. 2012.

Results: Broadness of Tg Rate of change of η at Tg “Strong” Glass Formers show broad Arrhenius-like variations Silica P2O5 “Fragile” Glass Formers show rapid η increase upon cooling Organic and Polymer liquids (epoxy-acid networks Tg 68 57 53 C for 1 5 10 mol %) Montarnal, Damien, Mathieu Capelot, Francois Tournilhac, and Ludwik Leibler. "Silica-Like Malleable Materials from Permanent Organic Networks." Science 334 (2011): 965-68. Web. 11 Nov. 2012.

Assessment Synthesized both soft and hard polymer networks with reversible covalent links Transesterification Reactions Mechanical Properties Insoluble Arrhenius-like variation in viscosity Separate topology freezing and glass transitions Montarnal, Damien, Mathieu Capelot, Francois Tournilhac, and Ludwik Leibler. "Silica-Like Malleable Materials from Permanent Organic Networks." Science 334 (2011): 965-68. Web. 11 Nov. 2012.

Further Research Ability to control or fine tune temperature of topology freezing transition Ability to control or fine tune glass transition temperature Choice of starting materials http://www.bestchemshows.com/

References (Pictures) molle.k.u-tokyo.ac.jp http://chemsrv1.uwsp.edu/macrog/lab/epoxyqc.htm http://www.sigmaaldrich.com/catalog/product/FLUKA/49670?lang=en&region=US http://www.bestchemshows.com/ http://sp.life123.com/bm.pix/how-to-change-brake-pads.s600x600.jpg http://image.made-in-china.com/2f0j00zBQTMaICHFcK/High-Purity-Silicon-Dioxide-Coating-Material.jpg http://images.clipartof.com/small/1047648-Royalty-Free-RF-Clip-Art-Illustration-Of-A-Cartoon-Black-And-White-Outline-Design-Of-A-Man-Carrying-A-Heavy-Problem-Rock.jpg http://chemistry2.csudh.edu/rpendarvis/thermoplas.GIF http://me.aut.ac.ir/staff/solidmechanics/alizadeh/Tensile%20Testing_files/image011.gif

References Montarnal, Damien, Mathieu Capelot, Francois Tournilhac, and Ludwik Leibler. "Silica-Like Malleable Materials from Permanent Organic Networks." Science 334 (2011): 965-68. Web. 11 Nov. 2012. Callister, William D., and David G. Rethwisch. Fundamentals of Materials Science and Engineering: An Integrated Approach. Hoboken, NJ: Wiley, 2012. Print.

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