Novel poly(p-xylylenes):: Thin films with tailored chemical and optical properties

Chemical vapor deposition polymerization is used to prepare submicron thin films of poly(p-xylylenes) with distinct chemical and optical properties. The polymers are prepared from 13 different [2.2]paracyclophanes with variable degrees of substitution and functionalities including hydroxy, methoxy, amino, triflate, or trifluoroacetyl groups. The chemical composition of the poly(p-xylylenes) is in good accordance with expected chemical structures as confirmed by X-ray photoelectron spectroscopy, microanalysis, and reflection-absorption infrared spectroscopy. For all polymers, basic optical properties, such as extraordinary and ordinary indices of refraction, are reported and reveal optical anisotropy of the coatings. Experimental data correlate well with data generated by a uniaxial Cauchy dispersion model. Furthermore, a distinct correlation between refractive indices and the electronic properties of the functional groups is observed. Similarly, optical birefringence depends on the nature of the functional group as significant variation in optical birefringence was found among the reported poly(p-xylylenes).