1 / 2

100nm

HO. OH. PDMS. Cl. Cl. 50 nm. Tailored Elastomers (Cornell University) Claude Cohen, T. Michael Duncan, Fernando Escobedo DMR-0349952. Polydimethylsiloxane Ionomers Goal : The study of PDMS ionomers with regular placement of low mol% of ionic groups along the chain.

dante-hicks
Download Presentation

100nm

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. HO OH PDMS Cl Cl 50 nm Tailored Elastomers (Cornell University)Claude Cohen, T. Michael Duncan, Fernando Escobedo DMR-0349952 Polydimethylsiloxane Ionomers Goal: The study of PDMS ionomers with regular placement of low mol% of ionic groups along the chain. Synthesis: Polycondensation followed by fractionation: Results: Transition metals (Zn or Co) ionomers precipitate as fluids but Ba and Ga ionomers precipitate as strong gels because of ionic aggregation. The physical properties of all the ionomers change with time because of slow conversion of intramolecular interactions into intermolecular interactions. New morphologies such as fibers and bundles of fibers are observed in Ba ionomers. Rheology of a PDMS ionomer with 1 mol % of barium ions at equilibrium after annealing at 150 C. All PDMS ionomers end up as elastic networks after aging or annealing at 150 C The equilibrium modulus is dominated by ion pairs, triplets etc and not by aggregates. 100nm STEM image of the above sample SAXS showing shoulder A self-consistent explanation for the observed structure-property relationships based on rheology, Scanning Transmission Electron Microscopy (STEM) and Small-Angle X-ray Scattering data is achieved. References: Manuscripts submitted to Macromolecules

  2. Tailored Elastomers (Cornell University)Claude Cohen, T. Michael Duncan, Fernando Escobedo DMR-0349952 Education and Outreach Simulations of semi-flexible chain networks Goal:Study the effect of chain stiffness in the absence of entanglements on the mechanical properties of elastomers usingMonte Carlo simulations Results: Three Ph.D. students are working on this project. Ashsish Batra and Dhananjay Bhawe will be graduating shortly and taking up industrial positions with Dow Chemical and Intel, respectively. Geoff Genesky is entering his 3rd year. One REU and five undergraduate students participated in research under this program over the past year. The PIs participated in Cornell’s Industrial Polymer Outreach Program and an educational program for High School teachers. The PIs and students participated in the National Chemistry Week by presenting demonstrations on polymers and elastomers at a local mall. The PI presented four lectures and offered hands-on demos for the Ithaca High School 10th graders. Stress vs. strain along with system snapshots Crosslinks (dots) and chain backbones (lines) shown separately Entanglement-free semiflexible chain networks demonstrate step-wise extension behavior that mimics very tough natural materials like the muscle protein Titin and Abalone shell. References: Phys. Rev. Letters 93,257804,2005; J. Chem. Phys. 123, 014909, 2005

More Related