Highly efficient EMI shielding composite films with excellent flexibility were fabricated by intercalating sliver nanowires into Ti3C2Tx nanosheets using nanocellulose as a green binder.
A new family of pH-responsive microgel-colloidosomes was prepared using microgel particles as the building blocks and macro-crosslinker. Our simple and versatile method used covalent inter-linking of vinyl-functionalised microgel particles adsorbed to oil droplets to form shells of doubly crosslinked microgels (DX MGs) and was demonstrated using two different microgel types.
Highly ordered and uniformly porous structure of conductive foams is a vital issue for various functional purposes such as piezoresistive sensing and electromagnetic interference (EMI) shielding. With the aids of Kevlar polyanionic chains, thermoplastic polyurethane (TPU) foams reinforced by aramid nanofibers (ANF) with adjustable pore-size distribution were successfully obtained via a non-solvent-induced phase separation. In this regard, the most outstanding result is the in situ formation of ANF in TPU foams after protonation of Kevlar polyanion during the NIPS process. Furthermore, in situ growth of copper nanoparticles (Cu NPs) on TPU/ANF foams was performed according to the electroless deposition by using the tiny amount of pre-blended Ti3C2Tx MXene as reducing agents. Particularly, the existence of Cu NPs layers significantly promoted the storage modulus in 2,932% increments, and the well-designed TPU/ANF/Ti3C2Tx MXene (PAM-Cu) composite foams showed distinguished compressive cycle stability. Taking virtues of the highly ordered and elastic porous architectures, the PAM-Cu foams were utilized as piezoresistive sensor exhibiting board compressive interval of 0–344.5 kPa (50% strain) with good sensitivity at 0.46 kPa−1. Meanwhile, the PAM-Cu foams displayed remarkable EMI shielding effectiveness at 79.09 dB in X band. This work provides an ideal strategy to fabricate highly ordered TPU foams with outstanding elastic recovery and excellent EMI shielding performance, which can be used as a promising candidate in integration of satisfactory piezoresistive sensor and EMI shielding applications for human–machine interfaces.
Graphical Abstract
pH-responsive microgels are crosslinked polymer colloid particles that swell when the pH approaches the pK a of the polybase or polyacid chains. Poly(vinylamine) (PVAM) has the highest primary amine content of all amine-containing polymers. Despite much effort the preparation of colloidally stable PVAM microgels is still elusive. Here, we introduce a simple and scalable, two-step method for preparation of pH-responsive PVAM microgels. First, non-aqueous dispersion (NAD) polymerization was used to prepare new monodisperse water-swellable poly(N-vinylformamide-co-2-(N-vinylformamido)ethyl ether microgels (PNVF-xNVEE). Here, x is the mol% of the alkali-stable crosslinker (NVEE) used. Alkali-hydrolysis of the PNVF-xNVEE microgels in water gave colloidally stable poly(vinylamine-co-bis(ethyl vinylamine)ether) (PVAM-xBEVAME) microgel dispersions. SEM images showed that both the PNVF-9NVEE and PVAM-9BEVAME microgel particles had cluster-like morphologies. The PVAM-xBEVAME particles were positively charged at pH values less than 12. The hydrodynamic diameters and electrophoretic mobilities increased strongly as the pH decreased. In order to demonstrate that primary amines could be used as chemical handles for conjugation, pyrene carboxylic acid was coupled using N-(3-dimethylaminopropyl)-N 0ethylcarbodiimide (EDC) chemistry and its presence confirmed by fluorescence microscopy. Because this new family of colloidally stable microgels has very high primary amine contents and was prepared by a scalable synthetic method there should be potential applications in a wide range of areas from surface coatings and new hybrid particles to delivery.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.