The present study demonstrates the successful deposition of poly­(ethylhexyl acrylate) thin films in a large-scale closed-batch initiated chemical vapor deposition (iCVD) system. A horizontal cylindrical stainless-steel vacuum tank, which is highly utilized in industrial vacuum applications, was used as iCVD reactor. The effects of substrate temperature, precursor ratio, and pressure on the deposition rates were studied, and the results showed that a deposition rate of 315 nm/min can be achieved in a single run at a reactor pressure of 600 mTorr. At a lower chamber pressure of 400 mTorr, deposition rate decreases, whereas film uniformity increases. By carrying out depositions at successive cycles, thicker films could be obtained, without the need for extensive monomer consumption. The yield percentage was found to be 3.5 for the films deposited in closed-batch system at 400 mTorr, which is 35-fold larger than that of the classical iCVD flow system.

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This study demonstrates the coating of a transparent and robust organic thin film having an excellent hydrophilicity-based antifogging property by an initiated chemical vapor deposition (iCVD) method. iCVD was able to synthesize linear and cross-liked poly­(acrylic acid) (PAA) from the vapors of acrylic acid (AA) and ethylene glycol dimethacrylate (EGDMA) using tert-butyl peroxide (TBPO) as an initiator. High deposition rates of up to 35 nm/min were observed at low deposition temperatures. It was possible to control the quantity of comonomers in the as-deposited films by adjusting the partial pressure of the EGDMA cross-linking agent. The effect of the EGDMA partial pressure on chemical structure was studied using Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) techniques. FTIR and XPS spectra of the as-deposited films showed the complete retention of the monomer functionality during iCVD. Hydrophilicities and large-area uniformity of the coatings were revealed using water contact angle measurements. The as-deposited PAA film was the most hydrophilic with a water contact angle (WCA) of 7.0°, while cross-linking with EGDMA increased the WCA values by up to 51.7°. Results of various tests, which were based on exposing the coated surfaces to artificial fog and hot water vapor, showed the excellent antifogging property of the coatings. Films were never fogged upon extensive and long-term exposure (2 months) to humid air.

This paper demonstrates the adhesive and hydrophobic modifications of glass, poly(ethylene terephthalate), and bamboo fabric surfaces using the initiated chemical vapor deposition (iCVD) process. iCVD of functional thin films is an all-dry and low-temperature alternative to the conventional wet coating processes. The as-deposited film is a terpolymer in which ethylhexyl acrylate and acrylic acid units comprised the pressuresensitive adhesive (PSA) part, while perfluorodecyl acrylate (PFDA) acted as the hydrophobic part due to its low surface energy fluorinated side groups. The PFDA composition in the iCVD terpolymer can be systematically varied by adjusting the initial gas feed fractions of monomers, as verified from FTIR and XPS analyses. The usage of the initiator tertbutyl peroxide during the depositions resulted in high deposition rates up to 80 nm/min at a filament temperature of 230 °C. The as-deposited films possessed high optical transparency with high shear and peel strength values. Depending on the chemical composition, the peel strength values were up to 0.5 N/25 mm on flexible PET substrates. After the coating, the highly porous bamboo surface not only became sticky due to the existence of the thin PSA layer on top but also the became near-superhydrophobic. The application of iCVD coating parameters to deposit hydrophobic PSA on moving large-area substrates under roll-to-roll deposition mode resulted in highly uniform coatings, which shows the potential of iCVD to be operated in industrial scales to functionalize the industrially important flexible substrates.

This study demonstrates the deposition of poly(ethylhexyl acrylate-co-ethylene glycol dimethacrylate) (P(EHA-co-EGDMA)) copolymer thin films in a batch type initiated chemical vapor deposition (iCVD) reactor. Crosslinked copolymers are desired for many applications because of their high stable properties. iCVD polymers derived by monomers bearing only one vinyl bond are usually linearly structured polymers and hence they are not durable, which is unfavorable for many real-world applications. Robust crosslinked iCVD films can be produced with the help of crosslinkers. In a typical iCVD process, copolymer thin film is produced by constantly feeding monomer vapor and crosslinker into the reactor. The monomer/crosslinker ratio should be precisely controlled for fabrication of reproducible thin films. In order to eliminate problems caused by adjusting the flowrates of precursors, a closed-batch type iCVD reactor was used for the first time in this study to produce copolymer thin films. The variation of precursors' partial pressures allowed control over the copolymer thin film structures. As compared with homopolymer, copolymers showed the better chemical and thermal stable properties. Almost 40% of the copolymer thin film remained on the substrate surface at an annealing temperature of 300 C, whereas the homopolymer film was completely removed at an annealing temperature of 280 C.