Solvothermal vapor annealing setup for thin film treatment: A compact design with in situ solvent vapor concentration probe

Abstract

A compact setup for in situ solvothermal vapor annealing of thin polymer films in the temperature range from room temperature to 70 °C is presented. The design is optimized to avoid solvent condensation in tubes and other components. The setup consists of a chamber, a gas delivery system, a commercial film-thickness measuring device, and a solvent vapor concentration sensor. The chamber is equipped with heaters and thermometers and is thermally insulated. It has windows to allow for penetration of xrays together with a sample table with a gas distributer to ensure homogeneous swelling of the polymer film. The computer-controlled gas delivery system has two different components, which can be used separately or in parallel (for mixed gas solvent annealing): (a) mass flow controllers and a bubbler system and (b) a commercial “controlled evaporation and mixing” system. The film-swelling ratio is determined in situ using optical reflectometry, and the solvent concentration in the exhaust gas is continuously monitored by UV-absorption. Test results are presented where the setup is used for swelling of ∼100 nm thick polystyrene and polyisoprene homopolymer films with toluene and acetone, respectively.