Surface Properties of Cellulose Acetate

Abstract

Cellulose acetates with different substitution degrees were investigated as to their surface tension properties and morphology. Atomic force microscopy (AFM) studies on membranes, obtained from solution in acetone/water nonsolvent mixtures, evidenced pores and nodules of different size and intensity, depending on the substitution degrees of cellulose acetate and on the water contents in nonsolvent mixtures. Modification of hydrophilicity, put into evidence by the apolar components and by the electron acceptor and electron donor parameters of the polar components, was correlated with the pores volumes — influenced both by their diameter and depths, and by surface roughness as illustrated by AFM images. Surface wettability trends were also studied by means of the free energy of hydration between compounds and water.

Fullerene‐based processable polymers as plausible acceptors in photovoltaic applications

“…Contact angle measurements were performed at 24 °C using an EasyDrop Krüss Instrument FM40 and Drop Shape Analysis software (1.90.0.14 version) on thin films (100 nm) deposited on glass substrate by spin coating (or evaporation in Joule effect vacuum chamber in the case of C 60 ). Six liquids were used as probes for surface energy calculations (methanol,55 dimethylformamide,56 ethylene glycol,57 propylene glycol,58 glycerol,57 and water57). Surface energies were calculated from contact angle measurements using Young's equation and Oweens‐Wendt model.…”

Influence of triphenylphosphonium pendant groups on the rheological and morphological properties of new quaternized polysulfone

“…For a water content value established at the solubility limit (DMF/water, 75/25 v/v), the depth value, and roughness parameters are lower. Pore sizes' enhancement is induced by the properties of the casting solutions, where the interactions owing to hydrogen bonding increase and different association phenomena occur 36, 37. Moreover, one can mention that the small hydrophilic characteristics given by the triphenylphosphonium pendant groups, where the electron‐donor interactions exceed the electron‐acceptor ones, influence film morphology and rheological properties, as well.…”

Water Molecular Dynamics in the Porous Structures of Ultrafiltration/Nanofiltration Asymmetric Cellulose Acetate–Silica Membranes

“…The determination of the accurate morphological features of porous media still represents a challenge as many properties depend not only on the void size's distribution but also on their connectivity and liquid-surface interactions [6]. Although there is a vast amount of scientific literature focused on microscopic and spectroscopic characterisation for elucidating the mechanisms of membrane selective transport in the active layer structures of integrally skinned cellulose acetate (CA) or cellulose esters membranes [4,[7][8][9][10][11][12], this subject is more complex in the study of hybrid CA and silica, CA/SiO 2 , asymmetric membranes constituting the system of this work [13,14]. Previous studies by de Pinho et al [15,16] on the characterisation of the water order and dynamics in asymmetric CA/SiO 2 hybrid membranes, covering a wide range of ultrafiltration (UF) and nanofiltration (NF) permeation properties, pointed to an essential indication that Nuclear Magnetic Resonance (NMR) relaxometry observables, which are strongly dependent on water-surface interactions due to confinement, can be reliably correlated with the membranes' asymmetric porous structures and selective permeation performance.…”