Coating of hydrophilic poly(hydroxypropyl methacrylate) thin films via pulsed-initiated chemical vapor deposition method

This study demonstrates the coating of poly(hydroxypropyl methacrylate) (PHPMA) thin films from the corresponding monomer HPMA using pulsed-initiated chemical vapor deposition (pulsed-iCVD) method. The advantages of pulsing the power delivered to the filament wires during iCVD through successive on–off duty cycles (DC) are outlined by considering the deposition rates, structure, and morphology of as-deposited PHPMA films. FTIR and XPS analysis of the as-deposited films verifies that pulsing the filament power produces thin films of PHPMA, which is structurally very similar to that synthesized using classical continuous power iCVD. However, there is up to 70% increase in deposition rate upon pulsing the filament power in comparison with the continuous power iCVD. AFM analysis of the as-deposited films shows that the film morphology can be controlled by varying the DC during pulsed-iCVD. At a DC of 85.7%, the most hydrophilic film is observed with a measured water contact angle of 31°.