Abstract:

Homoporous membranes (HOMEs) are featured as ordered through pores with homogenous pore sizes and pore geometries. HOMEs are the key to improve the separation precision, and to simultaneously increase selectivity and permeability. The concept of HOMEs and their structural characteristics are discussed at first. HOMEs are not only just a type of membranes with new structures but also represent one important aspect in the development of membrane separation. Then, the diverse methods to prepare HOMEs are summarized, and their specific advantages and disadvantages are discussed. Homoporous structures with tunable pore sizes typically in the range of 10—50 nm can be achieved based on the microphase separation of block copolymers (BCPs). The BCPs-enabled methods are distinguished from others for their simple processing, low cost, no need of cumbersome devices, and upscalability. The mechanism of selective swelling-induced pore generation of amphiphilic BCPs, its uniqueness in the tuneability of pore sizes and the geometries (including cylindrical and slitted-shaped pores), and inherently permanent hydrophilicity are discussed in detail. The perspectives of HOMEs derived from BCPs are finally discussed and the bottleneck in the BCP raw materials is identified. Furthermore, focused studies on HOMEs with pore sizes <10 nm, the design of new pore geometries with enhanced permselectivity and the expanded applications of HOMEs in diverse fields are suggested.

Key words: membranes, separation, homoporous membranes, nanostructure, block copolymers, selective swelling

摘要：

为进一步提高膜分离过程的精度,同步提升选择性和渗透性,分离膜孔径均一化是必然途径,均孔膜因此应运而生。首先讨论了均孔膜概念及其结构特点。均孔膜是孔径均一、孔道形状一致且垂直贯穿整个分离层的分离膜。然后介绍了制备均孔结构的不同方法,探讨了这些方法的优势和固有缺陷。利用嵌段共聚物微相分离的特性,可获取规整排列的、孔径在10～50 nm范围内连续可调的均孔结构,具有方法简便、无须特殊设备、易于放大制备等突出优势,是最有可能实现规模化生产的均孔膜制备方法。着重介绍了两亲嵌段共聚物选择性溶胀成孔方法的原理及其在孔径和孔型调节(圆柱孔、槽形孔)、自发永久亲水和制备过程绿色少污染等方面的特点。最后,讨论了嵌段共聚物基均孔膜发展的瓶颈,并指出应加强在孔径小于10 nm的均孔膜、孔型调变和应用领域等方面的研究。认为均孔膜不仅是一种新结构的分离膜,更代表着膜分离的发展方向。

关键词: 膜, 分离, 均孔膜, 纳米结构, 嵌段共聚物, 选择性溶胀