Anomalous Raman modes have been reported in several recent papers dealing with doped-and undoped-ZnO layers grown by different methods. Most of these anomalous Raman modes have been attributed to local vibrational modes of impurities or defects. However, we will show that most of the observed modes correspond to wurtzite-ZnO silent modes allowed by the breakdown of the translational crystal symmetry induced by defects and impurities.

Long-term hydrolytic and enzymatic degradation profiles of poly(ε-caprolactone) (PCL) networks were obtained. The hydrolytic degradation studies were performed in water and phosphate buffer solution (PBS) for 65 weeks. In this case, the degradation rate of PCL networks was faster than previous results in the literature on linear PCL, reaching a weight loss of around 20% in 60 weeks after immersing the samples either in water or PBS conditions. The enzymatic degradation rate in Pseudomonas Lipase for 14 weeks was also studied, with the conclusion being that the degradation profile of PCL networks is lower than for linear PCL, also reaching a 20% weight loss. The weight lost, degree of swelling, and calorimetric and mechanical properties as a function of degradation time were obtained. Furthermore, the morphological changes in the samples were studied carefully through electron microscopy and crystal size through X-ray diffraction. The changes in some properties over the degradation period such as crystallinity, crystal size and Young's modulus were smaller in the case of enzymatic studies, highlighting differences in the degradation mechanism in the two studies, hydrolytic and enzymatic.

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A study was carried out to determine the effects of graphene oxide (GO) filler on the properties of poly(ε-caprolactone) (PCL) films. A series of nanocomposites were prepared, incorporating different graphene oxide filler contents (0.1, 0.2, and 0.5 wt%) by the solution mixing method, and an in-depth study was made of the morphological changes, crystallization, infrared absorbance, molecular weight, thermal properties, and biocompatibility as a function of GO content to determine their suitability for use in biomedical applications. The infrared absorbance showed the existence of intermolecular hydrogen bonds between the PCL’s carbonyl groups and the GO’s hydrogen-donating groups, which is in line with the apparent reduction in molecular weight at higher GO contents, indicated by the results of the gel permeation chromatography (GPC), and the thermal property analysis. Polarized optical microscopy (POM) showed that GO acts as a nucleating point for PCL crystals, increasing crystallinity and crystallization temperature. The biological properties of the composites studied indicate that adding only 0.1 wt% of GO can improve cellular viability and that the composite shows promise for use in biomedical applications.

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