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A class of star-like co-polybenzimidazole (co-PBI) that consisted of hyperbranched PBI as core and linear PBI as arms is synthesized for dispersion of carbon nanomaterial (CNM) and fabrication of their composites. Such molecular architecture could promote the solubility of PBI by weakening the interchain interactions, and facilitate the adsorption of polymers on CNM with stronger interfacial interactions. As a result of these factors, the concentration of dispersion of CNM dispersed by co-PBI was generally several times higher than that of linear PBI dispersed CNM, demonstrating the much better dispersion effect of co-PBI on CNM. The co-PBI could also be employed as matrix for direct formation of CNM/polymer composites by a simple dispersing and casting process because of the good formability and mechanical properties of co-PBI. Model multi-walled carbon nanotube (MWCNT) based composites reveal the much higher mechanical performance of MWCNT/co-PBI composites than that of MWCNT/PBI composites due to the better dispersion state and stronger interfacial interactions in the former. The results presented here could provide an alternative approach for facile and large-scale fabrication of high-performance CNM/polymer composites.

The achieving of high-level mechanical reinforcement and efficient healing in intrinsic self-healing composite is challenging because the contradictory in chain mobility associated mechanism. Here we show that the covalent incorporation of molecular-scale polyhedral oligomeric silsesquioxane (POSS) by dynamic bonding into self-healing polymer can simultaneously realize these two requirements. The exemplified disulfide-based organic/inorganic hybrid dynamic network is directly constructed by a bottom-up strategy from pentaerythritol tetrakis (3-mercaptopropionate), glycol dimercaptoacetate and octathiol-POSS via oxidative coupling among thiol groups. It is showed that a 7 times improvement in modulus, 3 times increase in tensile strength, and 4.9 times increase in toughness can be simultaneously achieved by incorporation of 10 wt% POSS into the optimized disulfide-based matrix. As a result of the ultrasmall size of POSS and the dynamic interphase among POSS and matrix, the hybrid network exhibits comparable relaxation behavior with that of matrix and can be completely healed at moderate temperature.

Lysosome-targetable selenium-doped carbon nanodots (Lyso-Se-CDs) that can efficiently scavenge lysosomal •OH in living cells and mice were designed in this research. Se-CDs with redox-responsive fluorescence (λex = 379 nm, λem = 471 nm, quantum yield = 7.1%) were initially synthesized from selenocystine by a facile hydrothermal method, followed by the surface modification with morpholine, a lysosome targeting moiety. The as-synthesized Lyso-Se-CDs exhibited excellent colloidal stability, efficient scavenging abilities towards •OH, low biotoxicity, as well as good biocompatibility and lysosome targetability. Due to these desirable properties, Lyso-Se-CDs had been successfully utilized for rescuing cells from elevated lysosomal •OH levels. More importantly, Lyso-Se-CDs efficiently relieved phorbol 12-myristate 13-acetate (PMA) triggered ear inflammation in live mice. These findings reveal that Lyso-Se-CDs are potent candidates for treating •OH-related inflammation.

Selenium doped carbon quantum dots (Se-CQDs) are synthesized by a facile hydrothermal process. The Se-CQDs show narrow size distribution in the range of 3-4 nm, good optical properties, and high sensitivity in detection of various reactive oxygen species (ROS) as revealed by several characterizations. The Se-CQDs are then modified by three kinds of organelle targeting molecules with the aim of targeting detection of ROS in specific organelles. The confocal fluorescence studies on modified Se-CQDs and commercial organelle marker demonstrate the successful targeting detection of ROS in different organelles by our specific modified Se-CQDs.

Fiber reinforced thermoset composites (FRPCs) have received tremendous attention because of their merits of light weight, high modulus and high strength. However, the efficient recycling of the waste during the manufacturing and service life of FRPCs is still great challenge. This paper reports a newly designed dynamic crosslinked network based on Diels-Alder chemistry as matrix for fully recyclable aramid fabric reinforced composites. The DA network shows good thermomechanical properties owing to the incorporated aromatic amide bonds, and the overall performance can be readily tailored by adjusting the ratio of amide-containing component and flexible aliphatic component. The good reversibility of the DA network and highly efficient recovery of mechanical properties of recycled sample are confirmed. With optimized composition, the DA network exhibits good interfacial strength with aramid fiber that is comparable to that of widely used epoxy resin due to the interfacial hydrogen bonds among amide bonds between fiber and matrix. Moreover, the closed-loop recycling of both matrix and reinforced fabric without any other additive is also demonstrated. This paper presents the first report on recyclable aramid fiber reinforced composites and is expected to provide hints for future development of fully recyclable and high-performance FRPCs.