Nanofabrication within unimolecular nanoreactors

Nanoparticles (NPs) have been a research focus over the last three decades owing to their unique properties and extensive applications. It is crucial to precisely control the features of NPs including topology, architecture, composition, size, surface and assembly because these features will affect their properties and then applications. Ingenious nanofabrication strategies have been developed to precisely control these features of NPs, especially for templated nanofabrication within predesigned nanoreactors. Compared with conventional nanoreactors (hard templates and supramolecular nanoreactors), unimolecular nanoreactors exhibit (1) covalently stable nanostructures uninfluenced by environmental variations, (2) extensively regulated features of the structure including topology, composition, size, surface and valence due to the rapid development of polymer chemistry, and (3) effective encapsulation of abundant guests with or without strong interaction to achieve the function of loading, delivery and conversion of guests. Thus, unimolecular nanoreactors have shown fascinating prospects as templates for nanofabrication. Various NPs with expected topologies (sphere, rod, tube, branch, and ring), architectures (compact, hollow, core-shell, and necklace-like), compositions (metal, metal oxide, semiconductor, doping, alloy, silica, and composite), sizes (generally 1-100 nm), surface properties (hydrophilic, hydrophobic, reactivity, valence and responsivity) and assemblies (oligomer, chain, and aggregate) can be fabricated easily within reasonably designed unimolecular nanoreactors in a programmable way. In this review, we provide a brief introduction of the properties and types of unimolecular nanoreactors, a condensed summary of representative methodologies of nanofabrication within various unimolecular nanoreactors and a predicted outlook of the potential further developments of this charming nanofabrication approach.

Soft-Matter Nanotubes: A Platform for Diverse Functions and Applications

Self-assembled organic nanotubes made of single or multiple molecular components can be classified into soft-matter nanotubes (SMNTs) by contrast with hard-matter nanotubes, such as carbon and other inorganic nanotubes. To date, diverse self-assembly processes and elaborate template procedures using rationally designed organic molecules have produced suitable tubular architectures with definite dimensions, structural complexity, and hierarchy for expected functions and applications. Herein, we comprehensively discuss every functions and possible applications of a wide range of SMNTs as bulk materials or single components. This Review highlights valuable contributions mainly in the past decade. Fifteen different families of SMNTs are discussed from the viewpoints of chemical, physical, biological, and medical applications, as well as action fields (e.g., interior, wall, exterior, whole structure, and ensemble of nanotubes). Chemical applications of the SMNTs are associated with encapsulating materials and sensors. SMNTs also behave, while sometimes undergoing morphological transformation, as a catalyst, template, liquid crystal, hydro-/organogel, superhydrophobic surface, and micron size engine. Physical functions pertain to ferro-/piezoelectricity and energy migration/storage, leading to the applications to electrodes or supercapacitors, and mechanical reinforcement. Biological functions involve artificial chaperone, transmembrane transport, nanochannels, and channel reactors. Finally, medical functions range over drug delivery, nonviral gene transfer vector, and virus trap.

Hypercrosslinked porous polymer materials: design, synthesis, and applications

Hypercrosslinked polymers (HCPs) are a series of permanent microporous polymer materials initially reported by Davankov, and have received an increasing level of research interest. In recent years, HCPs have experienced rapid growth due to their remarkable advantages such as diverse synthetic methods, easy functionalization, high surface area, low cost reagents and mild operating conditions. Judicious selection of monomers, appropriate length crosslinkers and optimized reaction conditions yielded a well-developed polymer framework with an adjusted porous topology. Post fabrication of the as developed network facilitates the incorporation of various chemical functionalities that may lead to interesting properties and enhance the selection toward a specific application. To date, numerous HCPs have been prepared by post-crosslinking polystyrene-based precursors, one-step self-polycondensation or external crosslinking strategies. The advent of these methodologies has prompted researchers to construct well-defined porous polymer networks with customized micromorphology and functionalities. In this review, we describe not only the basic synthetic principles and strategies of HCPs, but also the advancements in the structural and morphological study as well as the frontiers of potential applications in energy and environmental fields such as gas storage, carbon capture, removal of pollutants, molecular separation, catalysis, drug delivery, sensing etc.

Hyper-Cross-Linking Mediated Self-Assembly Strategy To Synthesize Hollow Microporous Organic Nanospheres

Hollow microporous organic nanospheres (H-MONs) are prepared by using polylactide-b-polystyrene diblock copolymers (PLA-b-PS) as the precursor via a hyper-cross-linking mediated self-assembly strategy, in which the hyper-cross-linking PS block forms the microporous organic shell framework, and the degradable PLA block produces the hollow mesoporous core structure. The formation mechanism, morphology, and porosity parameters of the resulting H-MONs are systematically investigated. Moreover, based on the hyper-cross-linking generated rigid microporous organic frameworks, hollow microporous carbon nanospheres (H-MCNs) can be achieved by further pyrolysis progress. The obtained H-MCNs as electrode materials of a supercapacitor exhibit excellent electrochemical performance with specific capacitances of up to 145 F g^-1 at 0.2 A g^-1, with almost no capacitance loss even after 5000 cycles at 10 A g^-1. More especially, H-MONs can be further act as "nanoreactors" for the synthesis of Fe₃O₄ nanoparticles within hollow cores to construct magnetic core-shell Fe₃O₄@H-MONs nanocomposite materials. Our strategy represents a new avenue for the preparation of hollow morphology-controlled microporous organic polymers with various potential applications.