Precise control of the interior and outer shapes of polymer nanoparticles has found broad interest in nanosciences, for example, in fundamental studies of their physical properties, colloidal behavior, and corresponding applications. Realizing such control below the 50 nm scale (i.e., a size scale close to individual polymer chains) requires accurate manipulation of polymerization techniques and a judicious choice of the chemical structure in monomers and/or polymers. Here, we constructed a series of well-defined sub-50 nm homopolymer nanoparticles with controllable shape and highly ordered, complex internal structures with sub-5 nm domain spacings, starting from 1-vinyl-1,2,4-triazolium-type ionic liquids in a one-pot dispersion polymerization. With cryogenic electron microscopy and tomography, a morphological evolution of particle shape and interior at this extremely small size end, unusual for polymer colloids, was identified and investigated in detail.
covalently bonded organic moieties. Because of their unique properties derived from their tunable porous structures and the multiple functional groups, which can be included in their backbones, POPs have been actively investigated for multiple applications including gas storage/separation, [2,3] catalysis, [4][5][6] optoelectronics, [7,8] sensing, [9][10][11] energy storage, and conversion. [12,13] Aside from their high specific surface areas, they furthermore show excellent chemical stability, light-weight and a versatile chemistry for modification and functionalization. POPs can be further classified into two categories based on their crystallinity. Crystalline POPs are usually summarized under the name covalent organic frameworks [14][15][16] (COFs). Amorphous POPs are further divided, based on their structure or construction principles into hyper-crosslinked polymers [17,18] (HCPs), polymers of intrinsic microporosity [19,20] (PIMs), porous aromatic frameworks [21,22] (PAFs), and others. Recent research has seen increasing interest on amorphous POPs, especially when their skeleton is π-conjugated. In these highly porous networks, π-conjugation is superimposed with meso-/microporosities, i.e., electron transport in the polymer backbone is accompanied by mass transport in the porous system, which enable many intriguing properties and applications, e.g., in energy storage and conversion, [23,24] or optoelectronics. [25,26] As such, the importance of π-conjugation in porous polymer networks has defined another emerging functional POP class-the conjugated microporous polymers (CMPs). As mentioned, such CMPs [27] are a unique class of POPs exhibiting extended π-conjugated structures and permanent nanopores (Table S1). Earlier, McKeown et al. [28] discussed an important concept of preparing robust nanoporous materials by the covalent binding of planar molecules via a rigid spirocyclic linker. In 2007, Cooper et al. [29] reported a highly cross-linked, microporous poly(arylene ethynylene)s network, thus the first microporous polymer network with distinct π-conjugation and introduced the term "conjugated microporous polymer (CMP)" for this class of materials. Since their discovery, CMPs chemistry has intrigued scientists across the globe and been promoted rapidly, resulting in a strong growth in publications over the last decade. For instance, Thomas et al. [30] reported a spirobifluorene-type CMP with stable interface and application potential in organic light emitting diodes Since discovered in 2007, conjugated microporous polymers (CMPs) have been developed for numerous applications including gas adsorption, sensing, organic and photoredox catalysis, energy storage, etc. While featuring abundant micropores, the structural rigidity derived from CMPs' stable π-conjugated skeleton leads to insolubility and thus poor processability, which severely limits their applicability, e.g., in CMP-based devices. Hence, the development of CMPs whose structure can not only be controlled on the micro-but also on the macroscale have...
Soft actuators with integration of ultrasensitivity and capability of simultaneous interaction with multiple stimuli through an entire event ask for a high level of structure complexity, adaptability, and/or multi-responsiveness, which is a great challenge. Here, we develop a porous polycarbene-bearing membrane actuator built up from ionic complexation between a poly(ionic liquid) and trimesic acid (TA). The actuator features two concurrent structure gradients, i.e., an electrostatic complexation (EC) degree and a density distribution of a carbene-NH3 adduct (CNA) along the membrane cross-section. The membrane actuator performs the highest sensitivity among the state-of-the-art soft proton actuators toward acetic acid at 10−6 mol L−1 (M) level in aqueous media. Through competing actuation of the two gradients, it is capable of monitoring an entire process of proton-involved chemical reactions that comprise multiple stimuli and operational steps. The present achievement constitutes a significant step toward real-life application of soft actuators in chemical sensing and reaction technology.
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