Title
Cyclic allylic sulfide based photopolymer for holographic recording showing high refractive index modulation
Author
Paola Galli, Richard A. Evans, Chiara Bertarelli, Andrea Bianco
Year
2021
Journal
Journal of Polymer Science
Abstract
The development and characterization of a new holographic photopolymer system showing high refractive index modulation (∆n) is presented. It exploits the ring-opening polymerization reaction of a cyclic allylic sulfide (CAS) monomer, which is dispersed in a cellulose acetate butyrate (CAB) polymer matrix together with a blue sensitive radical photoinitiator. Volume Phase Holographic Gratings (VPHGs) obtained using these films show a very good fidelity of the transferred pattern, without deviations from the theoretical curves. A high ∆n is obtained due to the addition to this system of a tetrafunctional thiol crosslinker, which maximizes the material potential (formula limit) of the formulation. It also allows for a thermal post process of the gratings, further enhancing the ∆n. The photopolymer properties are evaluated as function of the monomer and thiol concentration to determine the optimal composition, at which a ∆n greater than 0.03 is obtained. This is a considerably high value in the field of photopolymers for holography and it enables the manufacturing of efficient holograms.
Instrument
FT/IR-4600
Keywords
photopolymer, cyclic Allylic Sulfide,