Controlled Bulk Properties of Composite Polymeric Solutions for Extensive Structural Order of Honeycomb Polysulfone Membranes

Abstract

This work provides additional insights into the identification of operating conditions necessary to overcome a current limitation to the scale-up of the breath figure method, which is regarded as an outstanding manufacturing approach for structurally ordered porous films. The major restriction concerns, indeed, uncontrolled touching droplets at the boundary. Herein, the bulk of polymeric solutions are properly managed to generate honeycomb membranes with a long-range structurally ordered texture. Water uptake and dynamics are explored as chemical environments are changed with the intent to modify the hydrophilic/hydrophobic balance and local water floatation. In this context, a model surfactant such as the polyoxyethylene sorbitan monolaurate is used in combination with alcohols at different chain length extents and a traditional polymer such as the polyethersufone. Changes in the interfacial tension and kinematic viscosity taking place in the bulk of composite solutions are explored and examined in relation to competitive droplet nucleation and growth rate. As a result, extensive structurally ordered honeycomb textures are obtained with the rising content of the surfactant while a broad range of well-sized pores is targeted as a function of the hydrophilic-hydrophobic balance and viscosity of the composite polymeric mixture. The experimental findings confirm the consistency of the approach and are expected to give propulsion to the commercially production of breath figures films shortly.

Breath-Figure Self-Assembly, a Versatile Method of Manufacturing Membranes and Porous Structures: Physical, Chemical and Technological Aspects

“…Well-defined micro- and nanoscaled porous polymeric architectures are in great demand for their use in advanced devices, including membranes [ 1 , 2 , 3 , 4 ], sensors [ 5 , 6 ], bio-engineering [ 7 , 8 ] and water-oil and size-selective separation processes [ 9 , 10 , 11 , 12 , 13 ]. One of the most versatile, simple, single-stage, and inexpensive methods, enabling manufacturing of porous polymer films with finely controlled topography, is so-called “breath-figure self-assembly” [ 14 , 15 ].…”

Two-Dimensional Materials: From Discovery to Application in Membrane Distillation/Crystallization Processes

“…Despite the simplicity with which droplets can be formed, the mechanism that controls the formation of BF geometry can be very complex and not perfectly unique. This may depend on the polymeric materials and solvents used, but also on changes in the surrounding experimental conditions, which make the management of water droplet dynamics somewhat difficult [119]. (f) Deposition for filtration is one of the most common and effective deposition methods.…”

“…(i) Honeycomb membranes possess a specific distribution of the pores on the surface of the partition walls and an enlarged porosity in addition to subtle dividing walls of a prescribed value. The preparation of these particular structures is based on the preparation of lithographic precision membranes according to a BF biospirated process [119]. The condensation waterdrops act as the imprinting agents on the polymer surface and with the balance between solvent evaporation and humid air condensation in a 3D construction, bee nest membranes can be obtained in a single pass.…”

Ordered Honeycomb‐Pattern Membrane†

“…Hydrophilic block also has a certain ability to stabilize water droplets and improve the regularity of the membrane. [ 51‐56 ] For the hydrophilic modification of membrane materials, monomers containing hydrophilic groups are usually used for block copolymerization and end‐group substitution. [ 55,57,58 ]…”