(637f) Responsive, Flexible Optics and Optoelectronics with Precision Polymer Thin Films and Multilayers
AIChE Annual Meeting
2023
2023 AIChE Annual Meeting
Materials Engineering and Sciences Division
Polymer Thin Films, Confinement, and Interfaces 2
Thursday, November 9, 2023 - 2:15pm to 2:30pm
In the first study, a model two-layer coating design consisting of relatively low index poly(1H,1H,6H,6H-perfluorohexyl diacrylate) (pPFHDA) was synthesized directly on top of poly(4-vinylpyridine) (p4VP). Broadband antireflection over the visible wavelength range (400â750 nm) was conferred to an optical-grade thermoplastic polyurethane (TPU) substrate, reducing its surface reflectance to less than 2%. The superior mechanical compliance of polymer ARCs over conventional inorganic coatings on the TPU substrate was demonstrated through biaxial tensile testing. The in situ spectroscopic ellipsometry capability integrated into the iCVD chamber, which was essential to realizing the optical coating design specifications with nm-level resolution and real-time index monitoring, will be described.
The second study describes a facile approach to synthesizing high refractive index polymers. Halogen molecules are incorporated into poly(4-vinylpyridine) thin films through exposure to halogen solutions or vapor. The halogen compounds are immobilized in the polymer matrix due to the formation of charge transfer complex (CTC): P4VP-IX (X = I, Br, and Cl). The maximum refractive indexes measured at 587 nm for P4VP-I2, P4VP-IBr, and P4VP-ICl were 2.08, 1.849, 1.774. The index for P4VP-I2 is among the highest values reported for polymers. It is shown gravimetrically that one halogen molecule absorbs for every pendent pyridine. The high refractive index is due to the high molar refractivity coupled to the compact nature of the complex; the densities of the complexed films were shown to be greater than 2.0 g cm-3. The spatial uniformity of the P4VP-I2 film was also characterized, showing standard deviations in refractive index and thickness of 0.0769 and 1.91%, respectively, over a 10mm diameter. Future opportunities for polymer thin films in optical and optoelectronic applications will be described.