Fabrication of Poly(N-isopropylacrylamide) with Higher Deposition Rate and Easier Phase Transition by Initiated Plasma Enhanced Chemical Vapor Deposition

Abstract

This study demonstrates the fabrication of thermoresponsive poly(N-isopropylacrylamide) (PNIPAAm) thin films using the initiated PECVD (i-PECVD) method, in which the initiator tert-butyl peroxide was used together with the monomer NIPAAm. The deposition rates, wettability properties, and the low critical solution temperature (LCST) of i-PECVD deposited PNIPAAM were compared with those of classical continuous wave and pulsed PECVD techniques without TBPO. The effect of plasma power, plasma operation mode, substrate temperature and the presence of initiator on the deposition rate and wettability properties of PNIPAAm thin films were investigated. The results showed that it was possible to tune the deposition rate and wettability properties of PNIPAAm thin films by changing the PECVD parameters. The highest deposition rate (47.9 nm/min) and the largest contact angle difference (18.3°) depending on the temperature were obtained using the i-PECVD method. The LCST value of i-PECVD-PNIPAAm was able to be tuned between 31 and 34 °C. Such value was dependent on the presence and amount of the initiator. On the basis of these results, the i-PECVD method can be considered as the most proper approach for producing of PNIPAAm with desired properties.