Photons Probe Entropic Potential Variation during Molecular Confinement in Nanocavities

Abstract

Abstract:In thin polymeric layers, external molecular analytes may well be confined within tiny surface nano/microcavities, or they may be attached to ligand adhesion binding sites via electrical dipole forces. Even though molecular trapping is followed by a variation of the entropic potential, the experimental evidence of entropic energy variation from molecular confinement is scarce because tiny thermodynamic energy density diverseness can be tracked only by sub-nm surface strain. Here, it is shown that water confinement within photon-induced nanocavities in Poly (2-hydroxyethyl methacrylate), (PHEMA) layers could be trailed by an entropic potential variation that competes with a thermodynamic potential from electric dipole attachment of molecular adsorbates in polymeric ligands. The nano/microcavities and the ligands were fabricated on a PHEMA matrix by vacuum ultraviolet laser photons at 157 nm. The entropic energy variation during confinement of water analytes on the photon processed PHEMA layer was monitored via sub-nm surface strain by applying white light reflectance spectroscopy, nanoindentation, contact angle measurements, Atomic Force Microscopy (AFM) imaging, and surface and fractal analysis. The methodology has the potency to identify entropic energy density variations less than 1 pJm −3 and to monitor dipole and entropic fields on biosurfaces.

Entropy and Random Walk Trails Water Confinement and Non-Thermal Equilibrium in Photon-Induced Nanocavities

“…It is unveiled that fractal dimensionality, and thus cavitations, are functions of the laser photon fluence. All algorithms exhibit a similar trend of fractal dimensionality with the number of laser pulses (laser fluence), although the fractal dimensionality derived with the power spectra methodology seems slightly different, as expected [ 13 , 25 ]. The fractal dimensionality initially dips, attaining its minimum value around 500 laser pulses and then rises again with a small gradient up to 10 3 laser pulses, Figure 4 a.…”

“…Today, both theoretical [ 14 , 15 , 16 , 17 , 18 , 19 ] and experimental advancements [ 20 , 21 ] gradually disclose the intriguing issues of thermodynamics of small systems, with major impacts on colloids, liquids, surfaces, interphases, chemical sensors, micro/nanofluidics, nanoporous media, proteins and DNA folding [ 10 , 22 , 23 , 24 , 25 , 26 , 27 ]. In cell biology, the presence of different nano-sized molecular scaffolds in the extracellular matrix environment implies a vast diversity of cellular activities and responses, including uncorrelated diverging drug delivery efficiencies [ 28 ].…”

Thermodynamic Properties and State Diagram of Gum Ghatti-Based Edible Films: Effects of Glycerol and Nisin

“…These results indicated that the moisture sorption processes of GG-based films were non-spontaneous, suggesting that the GG-based films do not absorb water from the environment spontaneously, which is desirable because the product is stable [25]. Cefalas et al [32] and Gavriil et al [33] discovered that an entropic potential alternation competes with a thermodynamic potential from the electric dipole attachment of molecular adsorbates in polymeric ligands and the power of an associated entropic nanothermodynamic potential is proportional to the number of nanocavities induced by photon treatment. Therefore, to properly understand the water sorption mechanism, both enthalpy-entropy compensation and competition theory should be considered in future research.…”

Optical and electrical properties of functional materials at the nanoscale

“…It is unveiled that fractal dimensionality, and thus cavitations, are functions of the laser photon fluence. All algorithms exhibit a similar trend of fractal dimensionality with the number of laser pulses (laser fluence), although the fractal dimensionality derived with the power spectra methodology seems slightly different [91], [145]. The fractal dimensionality initially dips, attaining its minimum value around 500 laser pulses and then rises again with a small slope up to 10 3 laser pulses, Figure 2.19a.…”