Surface characterization of plasma-modified low density polyethylene by attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy combined with chemometrics

Abstract Atomic layer deposition (ALD) on polymer substrates often requires a modification of the polymer surface properties. Plasma-enhanced ALD (PE-ALD) process is capable of establishing improved coating/substrate adhesion and layer properties by a plasma pre-treatment prior to the layer deposition. Low density polyethylene (LDPE) films were plasma treated using different gases (N2, O2, and N2+O2 mixture) for various exposure times. A novel method was proposed to reveal the chemical changes in the surface region of LDPE films with attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy combined with multivariate analysis. The loading plots of principal component analysis (PCA) revealed the formation of polar functional groups on the surface of LDPE films, as a result of plasma pre-treatment. PCA was also able to explore the differences and similarities in the chemical modifications of LDPE originated from different plasma gas and exposure time.