Using extensive Monte Carlo (MC) and molecular dynamics (MD) simulations, we investigate how spatial confinement reorganizes thin films of the twist-bend nematic ($N_{\mathrm{TB}}$). Confinement markedly amplifies otherwise elusive splay-bend order by frustrating the three-dimensional heliconical texture of bulk $N_{\mathrm{TB}}$. We find that a homochiral $N_{\mathrm{TB}}$ layer evolves into nonchiral splay-bend order via an interfacial smectic splay-bend-twist ($S_{\mathrm{SBT}}$) band with periodically alternating handedness. Generally, for planar anchoring between parallel walls, with the helical wave vector parallel to the plates, globally polar smectic splay-bend ($S_{\mathrm{SB}}$) layers form near the surfaces. Moving inward, the interfacial stack relaxes to bulk $N_{\mathrm{TB}}$ either directly through this $S_{\mathrm{SBT}}$ band or through a sequence that includes both the $S_{\mathrm{SBT}}$ and the nematic splay-bend-twist ($N_{\mathrm{SBT}}$) phases. The $N_{\mathrm{SBT}}$ band is most pronounced at large molecular bend angles, i.e., near the $N_{\mathrm{TB}}\text{−}{S}_{\mathrm{A}}$ boundary of the bulk phase diagram. Mode-resolved maps of elementary director distortions (splay, twist, bend, saddle-splay) corroborate this confinement-driven hierarchy. These results suggest thin-film routes to stabilize and diagnose modulated polar nematic and smectic organizations that are difficult to access in bulk.

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• Applications of soft matter
• Chiral symmetry
• Chirality
• Order parameters
• Phase diagrams
• Phase transitions
• Surface & interfacial phenomena
• Bent-core liquid crystals
• Liquid crystals
• Smectic liquid crystals
• Thermotropic liquid crystals