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Direct Probe Of Interfacial Structure During Mechanical Contact Between Two Polymer Films Using Infrared Visible Sum Frequency Generation Spectroscopy, Gary Harp, Ali Dhinojwala
Direct Probe Of Interfacial Structure During Mechanical Contact Between Two Polymer Films Using Infrared Visible Sum Frequency Generation Spectroscopy, Gary Harp, Ali Dhinojwala
Ali Dhinojwala
Infrared-visible sum frequency generation spectroscopy (SFG) has been used to study the interface between poly(vinyl-N-octadecylcarbamate-co-vinyl acetate) (PVNODC) and polystyrene (PS) films during mechanical contact. The films were contacted using a deformable semispherical poly(dimethylsiloxane) (PDMS) lens that can be easily adapted to incorporate friction and adhesion force measurements. A strong methyl symmetric peak and Fermi resonance band associated with the alkyl side chains of PVNODC are observed in the SFG spectrum. This suggests that the interface structure during mechanical contact is more ordered than the structure observed for PS/PVNODC bilayer films annealed above the melting and glass transition temperatures of PVNODC …
Probing Hidden Polymeric Interfaces Using Ir-Vis Sum-Frequency Generation Spectroscopy, Hasnain Rangwalla, Ali Dhinojwala
Probing Hidden Polymeric Interfaces Using Ir-Vis Sum-Frequency Generation Spectroscopy, Hasnain Rangwalla, Ali Dhinojwala
Ali Dhinojwala
Understanding the molecular-level processes underlying interfacial phenomena is important in the area of adhesion. We briefly introduce IR–visible sum-frequency generation spectroscopy (SFG) using a total-internal-reflection geometry for the study of polymer–air, polymer–solid, and polymer–polymer interfaces. The following examples, predominantly of work done in our lab, illustrating differences in molecular structure and dynamic properties at interfaces are presented: the air- and solid-interface structure of an amorphous polystyrene (PS) and a semicrystalline polymer with side-chain crystallinity, poly(octadecyl acrylate) (PA- 18); structure of a polymer–polymer interface between thin films of a semicrystalline polymer with side-chain crystallinity, poly(vinyl-N-octadecylcarbamateco-vinyl acetate), and an amorphous PS; thermal …