Controlled Separation and Release of Organoiodine Compounds Using Poly(2-methoxyethyl acrylate)-Analogue Microspheres

Abstract

A selective adsorption/desorption of organoiodine compounds was achieved on poly(2-methoxyethyl acrylate)-analogue microspheres, wherein the side chains in the polymers act as halogen-bonding sites. These results demonstrate that the halogen-bonding sites in the side chains exhibit adequate specific affinity for organoiodine compounds. In addition, the water-swollen pMEA-analogue microspheres (microgels) showed a thermoresponsive swelling/deswelling behavior that permitted a controlled release of the organoiodine compounds upon changing the temperature. Thus, it seems plausible that a variety of problems associated with, e.g., the recovery of rare iodine-containing compounds, such as the marine-derived iodine compounds, the delivery of iodine-containing drugs, or the removal of halogen compounds from wastewater, could be resolved by polymer microspheres that exhibit controlled halogen bonding.

Recent Developments in Polymeric Assemblies and Functional Materials by Halogen Bonding

“…In this regard, thermoresponsive microgels constituted from polymers with lower critical solution temperatures (LCST) are advantageous, as they can also release the guest molecules upon thermal collapse. In 2017, Suzuki and co‐workers utilized this concept to design thermoresponsive microgels from a series of poly(2‐methoxyethyl acrylate) ( pMEA )‐analogues by free radical precipitation polymerization in presence of a ethylene glycol dimethacrylate cross‐linker [47] . It was anticipated that the oxygen atoms of the methoxy groups available at the side chains of the PEGylated microspheres may act as Lewis‐base acceptors for complementary organoiodine donors and thus, can be used for adsorption and release of halogenated dyes [48] .…”

“…It was anticipated that the oxygen atoms of the methoxy groups available at the side chains of the PEGylated microspheres may act as Lewis‐base acceptors for complementary organoiodine donors and thus, can be used for adsorption and release of halogenated dyes [48] . pMEA showed excellent adsorption ability and extremely high selectivity for halogen‐containing xanthene dyes, such as eosin Y (EoY), erythrosine (Ery), phloxine B (PhB) and rose bengal (RB) over non‐halogenated ones such as orange II (Oril) and tartrazine (Ttz) (Figure 6A) [47] . By varying the number of methoxy or ethoxy groups in the polymer side chains, the strength of halogen bonding could be tuned due to alteration in the polarizability.…”

One-step synthesis and characterization of hydrophilic polymer microspheresimmobilized with polyphenylsulfone ultrafiltration membranes for protein rejection application

“…Depending upon the application, controlled polymer microstructure, i.e., its micrometer and submicrometer size range, is of major interest (Liu et al 2007). Such polymeric particles can be synthesized by various techniques including emulsion polymerization (Kureha et al 2017), suspension polymerization(Lv &Li 2020) and dispersion polymerization (Liu et al 2020) to form different polymeric particles such as core-shell, microdomain, hollow sphere, core corona and interpenetrating polymer network (Huang et al 2010). Emulsion polymerization and dispersion polymerization are time-consuming processes and are used for the synthesis of polymeric microspheres.…”

Nanostructure and thermoresponsiveness of poly(N-isopropyl methacrylamide)-based hydrogel microspheres prepared via aqueous free radical precipitation polymerization

“…The size of a typical microgel is in the range of several tens of nanometers to several micrometers, and thus, microgels can respond instantly to external stimuli such as changes in temperature, pH, and solvent. Due to their desirable properties, microgels have found applications, not only in a dispersed state, for example as carriers for drug-delivery systems, [5][6][7] in molecular separations, [8][9][10][11] and in functional catalysts, [12][13][14] but also in assembled states, for example as cell scaffolds, 15,16 sensors, 17,18 emulsi-ers, 19,20 and actuators. [21][22][23] The rst reported microgels were thermoresponsive poly(Nisopropyl acrylamide) (pNIPAm)-based microgels cross-linked with N,N 0 -methylenebis(acrylamide) (BIS).…”

“…1 The VPTT of microgels can be controlled by varying the constituent chemical species, such as (meth)acrylamide analogues, 1,25,26 N-vinylcaprolactam (VCL), 27,28 and oligo(ethylene glycol) methylester (meth)acrylates. 9,10,29 This is especially notable in the case of N-isopropyl methacrylamide (NIPMAm), which differs from NIPAm only by a single methyl group at the a-position, where the obtained pNIPMAm microgels have a VPTT of $43 C. [30][31][32][33][34][35][36][37][38] The VPTT of microgels can also be tuned via the copolymerization of NIPMAm with other chemical species, such as NIPAm or VCL. [39][40][41][42] Thermoresponsive microgels are mainly synthesized via aqueous free radical precipitation polymerization in water.…”