stretchable polymeric materials include the use of double networks, [4][5][6] nanocomposites, [7] and dynamic polymer networks. [8][9][10][11][12][13][14][15][16][17] Among these strategies, dynamic polymer networks based on dynamic crosslinks such as hydrophobic association, [8] metal-ligand interactions, [9,10] host-guest interactions, [11] dynamic covalent bonds, [12] ion-dipole interactions, [13] hydrogen bonds, [14][15][16] and ion bonds [17] have attracted much attention. Compared with traditional covalent bonds, these dynamic crosslinks can effectively dissipate energy via reversible bond formation/scission or exchange reactions, [9,12,18] resulting in highly stretchable polymeric materials. Despite this progress, the construction of dynamic polymer networks with a stretching ratio beyond 1000× remains a great challenge. Here, we report the preparation of superstretchable polymer networks by using two types of dynamic bonds. We utilize a small number of strong crosslinks to maintain the network integrity during stretching and a large number of weak crosslinks to dissipate energy. We found that the synergetic interplay between these two mechanisms resulted in a superstretchable polymer network that could be stretched to more than 10 000× its original length.Specifically, polybutadiene (PB) networks crosslinked by ionic hydrogen bonds and imine bonds were prepared and examined. PB oligomers (liquid state, M w = 9400) were functionalized by amine and carboxyl groups via a thiol-ene reaction to obtain PB-NH 2 -9.8% and PB-COOH-5%, respectively (the number indicates the degree of functionalization; Figure S1 and Table S1, Supporting Information). Oligomeric PB was chosen because of the abundant vinyl double bonds (90% 1,2-addition) available for amine and carboxyl modification. PB-NH 2 -9.8% and PB-COOH-5% could be completely dissolved, and gel permeation chromatography (GPC) analysis showed that M w of the functionalized PB was similar to that of the original PB, revealing that no chemical crosslinking occurred during the thiol-ene reaction ( Figure S2, Supporting Information). Then, PB-NH 2 -9.8%, PB-COOH-5%, and benezene-1,3,5-tricarbaldehyde were mixed at different ratios. In this formulation, crosslinked polymer networks were constructed via the weak ionic hydrogen bonds between the amine and carboxyl groups and the strong imine bonds from the reaction of amine and aldehyde groups (Figure 1; Movie S1, Supporting Information). [19,20] PB networks with fixed crosslink degrees at 9.8%, but varied ratios and different orders of formation of the ionic hydrogen bonds and imine bonds, were prepared. The resultant networks were labeled PB-ion-imine-x-y and PB-imine-ion-y-x, where x and y indicate the concentration Superstretchable materials have many applications in advanced technological fields but are difficult to stretch to more than 1000× their original length. A superstretchable dynamic polymer network that can be stretched to 13 000× its original length is designed. It is revealed that superstretchability of...

Highlights The current issues and recent advances in polymer/inorganic composite electrolytes are reviewed. The molecular interaction between different components in the composite environment is highlighted for designing high-performance polymer/inorganic composite electrolytes. Inorganic filler properties that affect polymer/inorganic composite electrolyte performance are pointed out. Future research directions for polymer/inorganic composite electrolytes compatible with high-voltage lithium metal batteries are outlined. Abstract Solid-state electrolytes (SSEs) are widely considered the essential components for upcoming rechargeable lithium-ion batteries owing to the potential for great safety and energy density. Among them, polymer solid-state electrolytes (PSEs) are competitive candidates for replacing commercial liquid electrolytes due to their flexibility, shape versatility and easy machinability. Despite the rapid development of PSEs, their practical application still faces obstacles including poor ionic conductivity, narrow electrochemical stable window and inferior mechanical strength. Polymer/inorganic composite electrolytes (PIEs) formed by adding ceramic fillers in PSEs merge the benefits of PSEs and inorganic solid-state electrolytes (ISEs), exhibiting appreciable comprehensive properties due to the abundant interfaces with unique characteristics. Some PIEs are highly compatible with high-voltage cathode and lithium metal anode, which offer desirable access to obtaining lithium metal batteries with high energy density. This review elucidates the current issues and recent advances in PIEs. The performance of PIEs was remarkably influenced by the characteristics of the fillers including type, content, morphology, arrangement and surface groups. We focus on the molecular interaction between different components in the composite environment for designing high-performance PIEs. Finally, the obstacles and opportunities for creating high-performance PIEs are outlined. This review aims to provide some theoretical guidance and direction for the development of PIEs.

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Three-dimensional (3D) covalent organic frameworks (COFs) are a new type of crystalline organic porous material, which have great application potential in various fields due to their complex pore structures and fully exposed active sites. The synthesis of 3D COFs with novel topologies is still challenging on account of limited secondary building units. Herein, we report a 3D COF with hea topology, which has never been reported before, utilizing a D 3hsymmetric precursor [2,3,6,7,14,15-hexakis(4-formylphenyl)triptycene (HFPTP)] and [tetrakis(4-amino biphenyl)methane (TABPM)]. 3Dhea-COFs display permanent porosity and a Brunauer−Emmett− Teller surface area of 1804.0 m 2 g −1 . Owing to the huge internal free volume of triptycene, 3D-hea-COFs show good adsorption performance for H 2 , CO 2 , and CH 4 . Moreover, theoretical calculation reveals that both triptycene and tetraphenylmethane units contribute to enhance hydrogen storage capacity. The novel topology in this work expands the family of 3D COFs and provides new possibilities for designing efficient gas storage materials.

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