The block copolymers (BCPS) can be microphase separated due to the thermodynamic incompatibility between the blocks by clicking the "blue" button on the top. The nano porous materials obtained by transforming the phase separation structure of ~ 5-100 nm into the pore have unique advantages in membrane separation, catalysis and drug delivery. However, simple and efficient methods of block copolymers are still to be developed. Selective swelling method, as a simple, chemical free, mass loss free and spontaneous surface functionalization method, can be used to prepare block copolymer porous materials with highly regular pore structure. At present, how to promote the pore forming process of selective swelling and significantly improve the pore forming efficiency has become the research focus in order to promote the scale-up preparation and practical application of block copolymer porous materials.
Based on the previous work, Wang Yong, Professor of Nanjing University of technology, has established a new method of pore formation by selective swelling, which has been widely used in the pore formation of polystyrene based and polysulfone based block copolymers (acc. chem. Res. 2016, 49, 1401-1408; macrolecules 2020, 53, 5-17). The previous research is mainly based on the thermal swelling process. Recently, the team proposed a new strategy of microwave enhanced selective swelling (Figure 1). The swelling agent molecules collide violently in the microwave environment, which causes the temperature of the system to rise sharply. The intense movement of molecules accelerates the speed of entering into the dense block copolymer film, and enhances the interaction between the swelling agent and the swelling block, so that the whole selective swelling and pore forming process can be completed within 30 s, so as to obtain the block copolymer nano porous film with continuous perforations.
Figure 1. Preparation of nanoporous block copolymer film by microwave enhanced selective swelling. (a) The change of ethanol temperature with microwave time; (b) the morphology of block copolymer films.
The rapid pore forming strategy of microwave enhanced selective swelling proposed by the team has good universality, which can achieve efficient pore forming of a variety of amphiphilic block copolymers, and can rapidly introduce high porosity into polysulfone block copolymers with high mechanical strength (Figure 2). Compared with the traditional methods such as thermal selective swelling and block etching, the microwave enhanced selective swelling method has the advantages of high efficiency and energy saving, which lays the foundation for the continuous production of block copolymer nanoporous materials.
Fig. 2. Contrast of selective swelling film thickness increase with microwave strengthening. Microwave swelling and thermal swelling were carried out at 800 W and 50 ℃, respectively.
This paper, published in macrolecules, is entitled "producing nanoorganisms in block copolymers within 30 s by microwave boosted selective swalling". The corresponding author of this paper is Professor Wang Yong of Nanjing University of technology, and the first author is Dr. Shi xiansong. The research was supported by NSFC.
Paper link:
https://pubs.acs.org/doi/10.1021/acs.macromol.0c00650
Relevant progress
Macrolecules, research group of Wang Yong, Nanjing University of Technology
He Feng research group of South University of science and technology has made important progress in the field of supramolecular self-assembly of block copolymers
Research group of Shi Weichao, Nankai University: formation mechanism of defect structure in block copolymer system
Research group of Yu Haifeng of Peking University has made progress in the field of supramolecular liquid crystal block copolymers
Chen Aihua group, Beijing University of Aeronautics and Astronautics: one pot high efficient preparation of cross-linked block copolymer nanowires
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