Asymmetric block copolymer membrane fabrication mechanism through self-assembly and non-solvent induced phase separation (SNIPS) process

Abstract

In this paper, the concept of the functional mechanism of copolymer membrane formation is explained and analyzed from the theoretical and experimental points of view. To understand the phase inversion process and control the final membrane morphology, styrene-acrylonitrile copolymer (SAN) membrane morphology through the self-assembly phenomena is investigated. Since the analysis of the membrane morphology requires the study of both thermodynamic and kinetic parameters, the effect of different membrane formation conditions is investigated experimentally; In order to perceive the formation mechanism of the extraordinary structure membrane, a thermodynamic hypothesis is also developed based on the hydrophilic coil migration to the membrane surface. This hypothesis is analyzed according to Hansen Solubility Parameters and proved using EDX, SAXS, and contact angle analysis of SAN25. Moreover, the SAN30 membrane is fabricated under different operating conditions to evaluate the possibility of morphological prediction based on the developed hypothesis.

How does Micro‐ and Macro‐Phase Separation of Block Copolymers Affect the Formation of Integral Asymmetric Isoporous Membranes? A Review on Effective Factors

“…To conclude, membrane formation through the SNIPS process includes both thermodynamic and kinetic variables, that should be optimized in a relatively narrow range. [ 177 ]…”

Modular Synthesis of Functional Block Copolymers by Thiol–Maleimide “Click” Chemistry for Porous Membrane Formation

“…Thus, SNIPS membranes are considered to be competitive to the commercially used track-etching technique but with the advantage of significantly higher flux due to hexagonal closed-packed cylindrical pores at the surface by self-assembly. The nanopore layer is above a microporous sponge-like structure, in addition to larger caverns, similar to classical NIPS membranes. , Since the introduction of the SNIPS process, many studies on SNIPS membranes dealing with processing conditions, − chemical modifications, − and potential applications ,, have been reported. In addition, the stimuli-responsive behavior of amphiphilic BCPs allows users to tune resulting BCP membrane properties by external triggers. ,,, Moreover, hydroxyl bearing BCPs like polystyrene- b -poly­(2-hydroxyethyl methacrylate) (PS- b -PHEMA) and polystyrene- b -poly­(solketal methacrylate) (PS- b -PSMA) are a major focus of the SNIPS membrane community due to adjustable pore sizes of the selective membrane layer and its ability to fractionate proteins for biomedical application. ,, Schöttner et al developed PS- b -PHEMA SNIPS membranes with a high water flux, and different chemical approaches were investigated to introduce stimuli-responsive moieties by postmodification of PS- b -PHEMA. ,, …”

Linear Block Copolymer Synthesis

“…Block copolymers play a dominant role in polymer science as their segmented structure is the source of a unique self-assembly behavior that cannot be achieved by random copolymers and has governed the development of research fields in which block copolymer compositions and their properties have been exploited. − Their macro- and microscopic behavior is unique and cannot be afforded by any other polymer architecture. , For example, nanostructure formation such as vesicles, micelles, and disks can be guided by block copolymer composition and functional group incorporation. , For the generation of porous membranes, coatings, and devices, − techniques have been developed to dictate the porous diameter and hierarchical structure of the membranes , to work as water purification systems, , in biomedical applications, or are developed for energy storage applications , in the form of battery membranes and dielectric capacitors and supercapacitors. , The influence of the block copolymer architecture and resulting nanoscopic structures can influence the outcome of biomedical applications. , Moreover, the addition of block copolymer-derived nanoscopic structures to hydrogels and lubrication fluids can have significant effects on their resulting mechanical and shear-stress behavior. , The directed self-assembly of block copolymers has developed into a versatile method to produce device-relevant structures in sub-10 nm length scales in thin films and has circumvented the feature size limits of conventional photolithography. , Bottom-up nanopatterning techniques have surpassed optical lithography gaining importance for high-volume manufacturing in the semiconductor industry. − The behavior of block copolymers in high-resolution guiding patterns will increase patterning efficiency and limit defects density . The leading commodity plastics are increasing their volume each year by over 10%, however, many of them do not fulfill the expectations we require of high-performance materials.…”

“…7,8 For example, nanostructure formation such as vesicles, micelles, and disks can be guided by block copolymer composition and functional group incorporation. 9,10 For the generation of porous membranes, coatings, and devices, 11−14 techniques have been developed to dictate the porous diameter and hierarchical structure of the membranes 15,16 to work as water purification systems, 17,18 in biomedical applications, 19 or are developed for energy storage applications 20,21 in the form of battery membranes 22 and dielectric capacitors and supercapacitors. 23,24 The influence of the block copolymer architecture and resulting nanoscopic structures can influence the outcome of biomedical applications.…”