APS Dallas

Download APS Dallas

Post on 20-Jul-2015

54 views

Category:

Education

0 download

Embed Size (px)

TRANSCRIPT

<p>Supramolecular Arrest and Activation for the Network for ation of Acid Catalyzed Epoxy Polymerization</p> <p>Supramolecular Arrest and Activation for the Network formation of Acid Catalyzed Epoxy PolymerizationMatthew J. Spencer, James V. Crivello, Chang Y. RyuDepartment of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute</p> <p>1</p> <p>MotivationEpoxy network formation triggered byHardening AgentAcid generation with UV</p> <p>Develop a one component system that cures quickly at low temperatures yet has RT stabilitySupramolecular chemistry </p> <p>Matthew J. Spencer, James V. Crivello, Chang Y. Ryu</p> <p>Structural AdhesivesPolyfuctional epoxide and polyamine hardening agentProblems with homogeneity, reaction begins upon mixing2</p> <p>SystemSuper Acid Generation by Onium SaltsPhoto-initiation</p> <p>Redox-initiation</p> <p>Polymerizations monitored byOptical PyrometryRheology</p> <p>Matthew J. Spencer, James V. Crivello, Chang Y. Ryu</p> <p>Photo polymerization is simple but limited in its applications. </p> <p>Thickness of sample limited by penetration depth of light.</p> <p>Optical Pyrometry uses inferred camera to monitor temperature of reaction.</p> <p>Rheometer can measure viscosity and elasticity and use these to establish the onset of crosslinking3</p> <p>2620 mJ/cm2Matthew J. Spencer, James V. Crivello, Chang Y. Ryu</p> <p>3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate Increased reactivity with 18 crown, complete suppression with 12 crown4</p> <p>Ring Opening PolymerizationsHighly exothermic due to ring strain</p> <p>Matthew J. Spencer, James V. Crivello, Chang Y. Ryu</p> <p>2700 mJ/cm2</p> <p>OP is well suited for highly exothermic reactions like ring opening polymerizations.</p> <p>Temperature is show to be related to % converstion for initial portion of graph5</p> <p>Supramolecular Arrest though Monomer DesignAlkyl glycidal ethers have long induction periods</p> <p>Increasing coordination by the monomer</p> <p>Matthew J. Spencer, James V. Crivello, Chang Y. Ryu</p> <p>Neopentlyglycol diclycidyl etherTrimethylolpropane triglycidyl ether</p> <p>Methyl glycidyl ether6</p> <p>Dynamic Shear RheologyMatthew J. Spencer, James V. Crivello, Chang Y. Ryu</p> <p>G* = G + iG = atan(G/G)</p> <p>Descrbe dynamic shearComplex dynamic modulusG the elastic modulusG the viscous modulous7</p> <p>Dynamic and Steady Shear Experiments</p> <p>DynamicSteady</p> <p>Model CompoundDipropylene Glycol Dyglicidal EtherMatthew J. Spencer, James V. Crivello, Chang Y. Ryu</p> <p>Just under 2 hours at 25C and under 3 minutes at 60C</p> <p>Steady shear provides method for in-situ mixing.</p> <p>Agreement of steady and dynamic indication of acid dispersion 8</p> <p> Modifying Reaction Kinetics with Crown Ethers</p> <p>18-crown-6</p> <p>1050 mJ/cm2Matthew J. Spencer, James V. Crivello, Chang Y. Ryu</p> <p>2620 mJ/cm2 Modifying Reaction Kinetics with Crown EthersMatthew J. Spencer, James V. Crivello, Chang Y. Ryu</p> <p>Increased reactivity with 18 crown, complete suppression with 12 crown10Matthew J. Spencer, James V. Crivello, Chang Y. Ryu</p> <p>Dynamic Shear Experiments with 15-Crown-5 at 40C</p> <p>Moles IOC-11 / moles Monomer ~ 0.002Crown is 10-20M% of monomer11</p> <p>The Supramolecular Complex2,6-di-t-butylpyridine is a proton trap, but will not neutralize larger species like an tertiary oxonium ion</p> <p>Crown ethers serve as a molecular ruler for acid species </p> <p>Matthew J. Spencer, James V. Crivello, Chang Y. Ryu</p> <p>Polyether ringPore Size (A)12-crown-4</p> <p>1.2-1.515-crown-5 1.7-2.2</p> <p>18-crown-6 2.6-3.2</p> <p>Summary &amp; Future WorkDevelopment of one component epoxy systemLong working life and low temperature cureControl of cationic ring opening polymerizationsMonomer DesignModifying reaction kinetics with crown ethersCrown ether size effect is observed</p> <p>Epoxy BlendsNMR Complex Determination </p> <p>Matthew J. Spencer, James V. Crivello, Chang Y. Ryu</p>