A Strong and Double-sided Self-Adhesive Hydrogel Sensor.

Flexible self-adhesive hydrogel sensors are attracting considerable concerns in recent years. However, creating a self-adhesive hydrogel sensor with excellent mechanical properties remains to be challenging. Herein, a double-sided self-adhesive hydrogel capable of strain sensor with high strength is demonstrated by penetration strategy. The middle poly(acrylic acid)-polyacrylamide/Fe3+ (PAA-PAM/Fe3+ ) tough layer endows the double-sided self-adhesive hydrogel with high mechanical properties, while the bilateral poly[2-(methacryloyloxy) ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide-polyacrylamide (PSBMA-PAM) adhesive layers are used to ensure excellent adhesiveness on diverse substrates. The tough layer of the double-sided self-adhesive hydrogel sensor shows a strong interface bonding force against the adhesive layer. The double-sided self-adhesive hydrogel sensor enables excellent adhesiveness on diverse substrates. More importantly, it can accurately detect different strains and human motions as a self-adhesive hydrogel strain sensor. This work manifests a new route of structural design to develop a self-adhesive hydrogel sensor with excellent mechanical properties that is suitable for a wide range of applications.

In Situ Surface-Initiated ATRP Mediated by Gallium-Based Liquid Metal Nanodroplets.

Surface-initiated atom transfer radical polymerization (SI-ATRP) is one of the most popular methods for surface modifications with functional polymer films, which has attracted significant attention in recent years. Herein, a facile method of gallium-based liquid metal (GLM) nanodroplets mediated SI-ATRP to prepare polymer brushes on GLM surfaces is reported. The ATRP initiator modified GLM (GLM-Br) nanodroplets act as a substrate for the in situ SI-ATRP and participate as a reducing agent to reduce Cu(II) deactivators to Cu(I) activators. UV-vis spectra confirm the feasibility of the in situ SI-ATRP and indicate that the thickness and density of polymer brushes play an important role in performing a successful ATRP on GLM nanodroplets surfaces. Homo- and block copolymers, poly(3-sulfopropyl methacrylate potassium salt) (PSPMA) and poly((2-dimethylamino)ethyl methacrylate-b-(3-sulfopropyl methacrylate potassium salt)) P(DMAEMA-b-SPMA) are successfully grafted to the GLM nanodroplets. Polymer brushes modified GLM nanodroplets show potential applications such as friction reduction and oil-water emulsion separation. GLM nanodroplets mediated SI-ATRP provides a novel and robust approach to preparing multifunctional GLM nanodroplets for different applications.

Facile Fabrication of Bio- and Dual-Functional Poly(2-oxazoline) Bottle-Brush Brush Surfaces.

Poly(2-oxazoline)s (POx) bottle-brush brushes have excellent biocompatible and lubricious properties, which are promising for the functionalization of surfaces for biomedical devices. Herein, a facile synthesis of POx is reported which is based bottle-brush brushes (BBBs) on solid substrates. Initially, backbone brushes of poly(2-isopropenyl-2-oxazoline) (PIPOx) were fabricated via surface initiated Cu0 plate-mediated controlled radical polymerization (SI-Cu0 CRP). Poly(2-methyl-2-oxazoline) (PMeOx) side chains were subsequently grafted from the PIPOx backbone via living cationic ring opening polymerization (LCROP), which result in ≈100 % increase in brush thickness (from 58 to 110 nm). The resultant BBBs shows tunable thickness up to 300 nm and high grafting density (σ) with 0.42 chains nm-2 . The synthetic procedure of POx BBBs can be further simplified by using SI-Cu0 CRP with POx molecular brush as macromonomer (Mn =536 g mol-1 , PDI=1.10), which results in BBBs surface up to 60 nm with well-defined molecular structure. Both procedures are significantly superior to the state-of-art approaches for the synthesis of POx BBBs, which are promising to design bio-functional surfaces.

Grafting Poly(ethylene glycol) Onto Single-Walled Carbon Nanotubes by Living Anionic Ring-Opening Polymerization.

Recent years, many methods have been developed to widen the practical application of single-walled carbon nanotubes (SWCNTs). Among them, PEGylation is a general strategy to endow functionality, biocompatibility as well as its good solubility. In this paper, poly(ethylene glycol) (PEG) is successfully grafted onto SWCNTs through living anionic ring-opening polymerization of ethylene oxide (EO). By controlling the amount of monomer and initiator, a series of PEGylated SWCNTs with different PEG molecular weight and density are prepared. Then, the as-prepared SWCNTs have been verified by thermogravimetric analyses (TGA), Raman spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS). Finally, the protein resistance property of the PEGylated SWCNTs is investigated. It is found that these PEGylated SWCNTs have a good protein resistance property and the higher the content of PEG grafted on the SWCNTs, the less adsorption amount of BSA and the larger capacity to resist protein absorption. This work provides a novel method to prepare PEGylated SWCNTs.

Mussel-Inspired Photografting on Colloidal Spheres: A Generalized Self-Template Route to Stimuli-Responsive Hollow Spheres for Controlled Pesticide Release.

A thermo-controlled pesticide release system composed of poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) thin film grafted polydopamine (PDA) (PDMAEMA-g-PDA) microcapsules is reported. SiO2 microparticles are used as a template to prepare PDA-coated SiO2 microparticles. The thermally-responsive PDMAEMA thin films are grafted on PDA surfaces using a metal-free surface-initiated photopolymerization approach without adding any photo-initiator or photosensitizer under UV light irradiation. The subsequent acid etching yields PDMAEMA-g-PDA hollow microcapsules. PDMAEMA-g-PDA microcapsules exhibit well-controlled release of avermectin (Av). The results show that the loading ability of PDMAEMA-g-PDA microcapsules of Av is up to 52.7% (w/w). The release kinetics of Av demonstrate that Av@PDMAEMA-g-PDA microcapsules exhibit temperature-controlled release performance. This work is significant for controlled release systems. This simple design is expected to be used in various applications, such as in controlled drug release and agriculture-related fields.

Adhesive polydopamine coated avermectin microcapsules for prolonging foliar pesticide retention.

In this work, we report a conceptual strategy for prolonging foliar pesticide retention by using an adhesive polydopamine (PDA) microcapsule to encapsulate avermectin, thereby minimizing its volatilization and improving its residence time on crop surfaces. Polydopamine coated avermectin (Av@PDA) microcapsules were prepared by emulsion interfacial-polymerization and characterized by Fourier transform infrared spectroscopy, energy dispersive X-ray spectroscopy, field-emission scanning electron microscope, and transmission electron microscopy. The in situ synthesis route confers Av@PDA microcapsules with remarkable avermectin loading ability of up to 66.5% (w/w). Kinetic study of avermectin release demonstrated that Av@PDA microcapsules exhibit sustained- and controlled-release properties. The adhesive property of Av@PDA microcapsules on different surfaces was verified by a comparative study between Av@PDA and passivated Av@SiO2 and Av@PDA@SiO2 capsules with silica shell. Moreover, PDA shell could effectively shield UV irradiation and so protect avermectin from photodegradation, making it more applicable for foliar spraying. Meanwhile, it is determinated that Av@PDA microcapsules have good mechanical stability property.