Precursor-Assisted Fabrication of Thymine-Containing Surface Relief Gratings with Enhanced Patternability and Structural Stability

Abstract

The scalable fabrication of high-amplitude surface relief gratings (SRGs) remains a central challenge due to the trade-off between molecular functionality and photodeformability. In this work, we present a precursor-assisted fabrication strategy using chlorine-functionalized polymers as both synthetic precursors and structural benchmarks to elucidate the intrinsic photoresponsive behavior of the polymer backbone. Flexible chain segments were introduced to lower the glass transition temperature (Tg), improving SRG processability while preventing large-scale film cracking. Through compositional engineering of two polymer series, we demonstrate that thymine-mediated intermolecular hydrogen bonding increases Tg (up to 98.1 °C) and suppresses photoinduced mass transport. Although these interactions reduce the efficiency of direct laser inscription, the processable chlorine-functionalized precursor enables rapid fabrication of master gratings with amplitudes approaching 1070 nm. More importantly, the precursor-assisted soft-lithography strategy effectively decouples molecular functionality from direct-writing constraints, enabling the scalable fabrication of thymine-functionalized SRGs with high structural fidelity. High-fidelity pattern transfer was achieved with an amplitude loss of only 2.1%, significantly outperforming typical replicated systems. The resulting thymine-functionalized SRGs exhibit excellent long-term stability (3.4% modulation-amplitude decay after four months), good environmental stability under water, high humidity, and temperatures below the glass transition temperature, and rapid solvent-triggered erasure in THF. Preliminary optical-response experiments further demonstrate that the fabricated SRGs can convert interfacial molecular interactions into measurable diffraction signals while preserving their structural integrity. Overall, this work establishes an effective precursor-assisted fabrication strategy for scalable thymine-functionalized SRGs and provides a robust optical transduction platform for future target-specific sensing and reconfigurable photonic applications.