Nano-Hydroxyapatite Particle Brushes via Direct Initiator Tethering and Surface-Initiated Atom Transfer Radical Polymerization for Dual Responsive Pickering Emulsion

Abstract

Well-defined polymer-grafted solid inorganic nanoparticles (NPs) are imperative for practical applications in various fields based on the prerequisite of facile initiator immobilization. Direct atom transfer radical polymerization (ATRP) initiator-tethered solid NPs are described using 2-bromo-2-methylpropionic acid as a tetherable initiator. To illustrate the versatility of the proposed strategy, nano-hydroxyapatite (n-HAP) nanocrystals (NCs) were selected to demonstrate the morphology-controlled synthesis of 2-bromo-2-methylpropionate (2-BrMP) group-immobilized n-HAP (n-HAP-Br) NCs. When water was employed as the sole solvent, the continually introduced 2-BrMP groups altered the surface hydrophobic capacity of the n-HAP-Br NC and thus led to unavoidable aggregation of n-HAP-Br NCs. The synthesis of individually dispersed n-HAP-Br NCs was achieved by rational adjusting polarity of the aqueous medium through adding a portion of water-miscible organic solvents. The type and concentration of added water-miscible organic solvents had critical effects on the morphology and particle size of n-HAP-Br NCs. To verify the efficiency of the tethered initiator, n-HAP-g-poly2-(dimethylamino) ethyl methacrylate (n-HAP-g-PDMAEMA), n-HAP-g-polyacrylonitrile (n-HAP-g-PAN), and n-HAP-g-polymethyl methacrylate (n-HAP-g-PMMA) were fabricated by surface-initiated ATRP (SI-ATRP). Acting as a solid particle emulsifier, the designed n-HAP-g-PDMAEMA-stabilized Pickering emulsion displayed dual pH and temperature response with reversible behaviors. This work presents a versatile and simple way for the fabrication of initiator-immobilized solid NPs (e.g., n-HAP NCs, gibbsite nanoplatelets, and γ-FeOOH nanofibers) ready for polymer grafting and thus enables promising performance in widespread applications.

Controllable Regulation of Diesel Oil-in-Water Pickering Emulsion Stability by Multiresponsive Recyclable Magnetic Polymer Brush Microvessels

“…Notably, the average Pickering emulsion droplet size was virtually maintained when the MNPDNML microsphere concentration exceeded 1.0 wt %. It was because the MNPDNML microspheres sufficiently coated the water–diesel interface, so there was little change in emulsion droplet size when the microsphere concentration was increased …”

“…It was because the MNPDNML microspheres sufficiently coated the water−diesel interface, so there was little change in emulsion droplet size when the microsphere concentration was increased. 57 In order to investigate the effect of water−oil ratio on the stability performance of Pickering emulsion, the mixtures with different water−oil volume ratios were emulsified by fixing the concentration of MNPDNML microspheres (1.0 wt) at the system environmental pH of 10, and the results are shown in Figure 6b. With the increase of diesel volume fraction, the emulsion droplet size distribution was broadened, and Pickering emulsion stability deteriorated.…”

Coffee Beverage: A New Strategy for the Synthesis of Polymethacrylates via ATRP

“…Equally important is the solubility of the monomers in the individual media, which determines the selection of the reaction solvent. Recently, ATRP of 2-(dimethylamino)ethyl methacrylate (DMAEMA) were successfully carried out in alcoholic beverages [30], ethanol/water [30] and acetone/water mixture [31], as well as in environmentally harmful solvents such as N,N-dimethylformamide (DMF) [32,33], dimethyl sulfoxide (DMSO) [34], toluene [35], anisole [36] or methanol [37]. Despite the polymerization carried out for hydrophilic monomers, the application of pure water as a polymerization medium is still difficult.…”

Hypoxia/Temperature/pH Triple Stimuli–Responsive Block Copolymers: Synthesis, Self‐Assembly, and Controlled Drug Release

“…[50,51] Hence, DMAEMA was widely used in multiple responsiveness systems. [52][53][54][55] Zou and Yuan synthesized amphiphilic poly(ɛ-caprolactone)-SS-poly(2-(N,N-dimethylamino)ethyl methacrylate) (PCL-SS-PDMAEMA) copolymers by ring-opening polymerization and realized intelligent polymer materials with magnetic, temperature, and redox multiple response properties. [56] Han and co-workers prepared PDMAEMA-b-poly(acrylic acid) (PAA) copolymers by atom transfer radical polymerization (ATRP) process and investigated the thermal and pH dual response mechanisms.…”