This work presents a new technique to study polymers under strong geometrical confinement in nanoporous films. The procedure is based on sensing the changes of the optical properties of the porous matrix due to polymer imbibition into the pores by using optical interferometry. A simple theoretical model is used to correlate the timedependent optical thickness of the film with the polymer dynamics as a function of temperature. To test the method applicability, the imbibition of ethyl vinyl acetate in porous silicon membranes was studied. A large variation of the polymer viscosity was measured by varying the temperature from 20 to 110 °C. In addition, the confinement degree was varied in about 2 orders of magnitude by using matrices with different pore radius. A remarkable decrease in the viscosity was observed when the mean pore radius was reduced. Moreover, the interferometric technique enables the study of very low molecular weight polymers as well as measuring along a wide range of temperatures in a single nondestructive experiment.

The pursuit of sustainable and environmentally friendly materials has been powered by environmental concerns and the decline in oil reserves. Among the different routes toward this end, the replacement of oil-based materials by renewable materials stands out. In this way, protein based materials have gained interest. This review article summarizes the progress achieved in the synthesis of hybrid protein/synthetic polymer nanoparticles which have the potential to be used in industrial applications. Although technical achievements and efficacy proofs concerning the increased compatibility of polymer/protein are already available, practical implementation in industry still represents an additional challenge and should be the focus of interest in future research. The available literature supports the potential of hybrid protein/polymer nanoparticles in the production of ecofriendly alternatives for large scale applications as coatings, paints, adhesives and films.

A fluid dynamic model for imbibition into closed-end, axisymmetric pores having diameters that change as a function of the pore depth is presented. Despite the fact that liquid invasion into nonbranched closed-end pores is characterized by a wealth of different transient and/or metastable nonequilibrium stages related to precursor film formation, we show that a simple hydraulic model accounting for geometry-and air compression-induced deviations from classical Lucas-Washburn dynamics precisely describes the imbibition dynamics except at the late stage. The model was validated by laser interferometry experiments with submillisecond temporal resolution. Imbibition of three simple liquids (isopropanol, ethanol, and hexane) into self-ordered anodic alumina membranes containing arrays of parallel closed-end nanopores characterized by slight conicity was studied. The model provides an improved description of nanoscale fluid dynamics and allows geometric characterization of nanoporous membranes by their imbibition kinetics accounting for the back pressure of the compressed gas. Thus, a precise calibration of porous membranes with simple liquids becomes possible, and changes in the mean pore diameter as a function of the pore depth can be assessed.

When a macroscopic droplet spreads, a thin precursor film of liquid moves ahead of the advancing liquid-solid-vapor contact line. Whereas this phenomenon has been explored extensively for planar solid substrates, its presence in nanostructured geometries has barely been studied so far, despite its importance for many natural and technological fluid transport processes. Here we use porous photonic crystals in silicon to resolve by light interferometry capillarity-driven spreading of liquid fronts in pores of few nanometers in radius. Upon spatiotemporal rescaling the fluid profiles collapse on master curves indicating that all imbibition fronts follow a square-root-of-time broadening dynamics. For the simple liquid (glycerol) a sharp front with a widening typical of Lucas-Washburn capillary-rise dynamics in a medium with pore-size distribution occurs. By contrast, for a polymer (PDMS) a precursor film moving ahead of the main menisci entirely alters the nature of the nanoscale transport, in agreement with predictions of computer simulations.

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In this work, we study the optical response of structures involving porous silicon and porous alumina in a multi-layered hybrid structure. We performed a rational design of the optimal sequence necessary to produce a high transmission and selective filter, with potential applications in chemical and biosensors. The combination of these porous materials can be used to exploit its distinguishing features, i.e., high transparency of alumina and high refractive index of porous silicon. We assembled hybrid microcavities with a central porous alumina layer between two porous silicon Bragg reflectors. In this way, we constructed a Fabry-Perot resonator with high reflectivity and low absorption that improves the quality of the filter compared to a microcavity built only with porous silicon or porous alumina. We explored a simpler design in which one of the Bragg reflectors is replaced by the aluminium that remains bound to the alumina after its fabrication. We theoretically explored the potential of the proposal and its limitations when considering the roughness of the layers. We found that the quality of a microcavity made entirely with porous silicon shows a limit in the visible range due to light absorption. This limitation is overcome in the hybrid scheme, with the roughness of the layers determining the ultimate quality. Q-factors of 220 are experimentally obtained for microcavities supported on aluminium, while Q-factors around 600 are reached for microcavities with double Bragg reflectors, centred at 560 nm. This represents a four-fold increase with respect to the optimal porous silicon microcavity at this wavelength.

Organo-inorganic perovskites have been intensively studied due to its potential application in low cost and great efficient energy conversion in solar cells. Despite the great improvement in the quality of organo-inorganic perovskite films, a wide dispersion into the same batch of perovskite-based devices keep being an obstacle to obtaining highly reproducible results. For that reason new and efficient strategies for testing deposition results is imperative for the next step. Here we present a simple and efficient procedure for characterizing the optical and morphological properties based on the simultaneous reflectance and transmittance measurements under normal incidence over a MAPbI3 film. The proposed method provides qualitative and quantitative morphological information associated with the film roughness as well as information about the position of the optical gap and possible contributions to the optical dispersion in the structure that can be used as a simple diagnostic tool to optimize the film deposition. Results are contrasted and validated with electronic and atomic force microscopy, as well as first-principles calculations.

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