Substrate effects on the surface properties of nylon 6

Thin nylon 6 films spin coated onto different substrates were characterized by wide-angle X-ray scattering (WAXS), Fourier transformation infrared (FTIR) spectroscopy, FTIR trichroic analysis and water contact angle (CA) measurements. The morphology and hydrophilicity of the nylon 6 surface were found to be greatly influenced by the nature of the substrate. The film surface contained primarily α-form crystals when it was prepared using hydrophobic substrates. This film was more hydrophobic. However, for hydrophilic substrates, the film surface comprised mainly γ-form crystals and demonstrated greater hydrophilicity. FTIR trichroic analysis of the Nsingle bondH stretching vibration mode revealed that the presence of a hydrophilic substrate caused the Nsingle bondH stretching bonds on the film surface to align preferentially in the direction perpendicular to the surface. Such effects were attributed to molecular interactions between the Nsingle bondH bonds of the polymer and Sisingle bondO bonds of the hydrophilic substrate.