POS2-0229
Local Orientation of Polyetherimide at Carbon Interfaces Probed by Sum-Frequency Generation Spectroscopy
Topic
S2. High-End Characterization/Polymer Physics/Properties
When and Where
Sep 29, 2026
08:30 - 09:30
Room 301 (Grand Ballroom)
Session Chairs
Hae Jung SON
Boseok KANG
Presenter(s)
Kazuma Aoki (Kyushu University)
Co-Author(s)
Abstract
Aggregation states of polymer chains at carbon interfaces play a crucial role in determining interfacial adhesion and macroscopic mechanical properties of carbon fiber-reinforced thermoplastics. In particular, super engineering plastics are promising matrix polymers for aerospace applications because of their high heat resistance, mechanical performance, and processability. However, aggregation states at buried polymer/carbon interfaces remain difficult to directly characterize. Here, we investigated the local orientation of polyetherimide (PEI), an amorphous super engineering plastic, at carbon interfaces with different surface treatments using interface-selective sum-frequency generation (SFG) vibrational spectroscopy. As model carbon adherends, CaF₂ substrates coated with carbon layers prepared by arc discharge were used. The as-prepared carbon surface and the surface subjected to plasma treatment were denoted Pristine and Plasma, respectively. The water contact angle was 63° on Pristine, whereas a water droplet completely spread on Plasma, indicating the introduction of hydroxyl groups onto the Plasma surface. PEI films were spin-coated from its chloroform solution and then laminated to prepare sandwiched films. SFG spectra for PEI at both interfaces showed peaks at around 1,740 and 1,780 cm⁻¹, which were assigned to the symmetric and antisymmetric stretching vibrations of imide carbonyl groups, respectively. This indicates that the carbonyl groups are oriented at the carbon interface regardless of the surface chemical state of the carbon layers. In contrast, the peak positions of the carbonyl groups at the Plasma interface were red-shifted by approximately 5 cm⁻¹ relative to those at the Pristine interface, suggesting hydrogen-bond formation between PEI carbonyl groups and hydroxyl groups on the carbon surface. These results reveal that the chemical state of carbon interfaces could control the local orientation and interactions of PEI chains.
