A user is seeking a hydrophilic polymer that can sublimate in a vacuum of approximately 10-7 torr for a liquid mirror project, specifically to create a thin film barrier between a silver coating and an ionic liquid. Key requirements include hydrophilicity and semi-volatility, with a focus on minimizing surface irregularities. The discussion shifted towards small-molecule organic materials, which may be easier to sublime compared to polymers. Suggestions included using a parylene conformal coat followed by gold deposition, although alternatives like aluminum or chromium were also considered for their non-reactivity. Concerns were raised about the reactivity of silver with the ionic liquid, emphasizing the need for a stable barrier.