One-Step Synthesis of K+-Selective Methacrylic-Acrylic Copolymers Containing Grafted Ionophore and Requiring No Plasticizer

Abstract

A main drawback in the application of ion sensors that are based on plasticized polymeric membranes is the problem of leaching of plasticizer and ionophore. Leaching problems can be critical in solid-state minidevices, e.g., ion-selective electrodes or optodes, where a thin ion sensing polymer ®lm is often empolyed. To resolve such problems, we have designed simple methacrylic-acrylic copolymers that required no plasticizer and which include immobilized polymerizable but hydrophilic ionophores such as 4-acryloylamidobenzo-15-crown-5 (AAB15C5) and 4-acryloylamidobenzo-18-crown-6 (AAB18C6) that would normally be susceptible to leaching from plasticized PVC membranes, were used as model ionophores for the immobilization studies. These crown compounds are attractive since they can be employed as a monomeric unit in the copolymer recipe and thus no additional synthesis or polymer modi®cation is required. Copolymers suitable for ion-selective membrane application were synthesized by introducing more than 80 wt. % of n-butyl acrylate to yield copolymers of T g 's between 7 20 to 7 30 C. The molecular weight distributions of these copolymers were M w`5 0 000 Da and they contained 2 to 6 wt. % of immobilized crown ether ionophores. The`self-plasticising' methacrylic-acrylic membranes formed with these acryloyl crown ethers demonstrated good potentiometric responses to potassium ion. In contrast, AAB15C5 and AAB18C6 entrapped in membranes in a more classical ion selective membrane recipe, even when a plasticizer was included, were still inferior in their response to those with membranes containing immobilized ionophores. The restricted mobility of the immobilized ionophores in these self-plasticizing polymer matrices did not appear to hinder the normal complexation behavior of these ionophores. This was inferred from the possible formation of the usual 2:1 and 1:1 ionophore-cation complexes of AAB15C5 and AAB18C6, respectively, in these new copolymer matrices.

A Hydrogen Ion-Selective Sensor Based on Non-Plasticised Methacrylic-acrylic Membranes

“…Preparation of methacrylic-acrylic polymers: Procedure for the synthesis of the copolymer of methyl methacrylate (MMA) and n-butyl acrylate (nBA) as reported before (11,13) . The polymerisation was accomplished by adding 2.44 g of MMA and 3.06 g nBA and 0.001 g of benzoyl peroxide as initiator to 5 mL of dry benzene.…”

“…An obvious solution to the problem of non-biocompatibility caused by plasticiser is to eliminate the use of plasticiser altogether. This has been attempted with polymer matrix such as sol-gel (8) and also methacrylic-acrylic copolymers (9)(10)(11)(12)(13)(14) . In this work, we have synthesised a methacrylic-acrylic copolymer and employed it as a non-plasticised membrane for hydrogen ion-selective sensor application.…”

Influence of Methacrylic-Acrylic Copolymer Composition on Plasticiser-free Optode Films for pH Sensors

“…Recently, the acrylate family of polymers has been used successfully as membranes for potentiometric ion sensors (4)(5)(6) without the use of a plasticiser. Since then, the application of this class of plasticiser-free polymers has been extended to optical ion sensors, particularly membranes based on cross-linked dodecyl acrylate (7) and decyl methacrylate (8) .…”

Polymethacrylate polymers with appended aluminum(III)-tetraphenylporphyrins: Synthesis, characterization and evaluation as macromolecular ionophores for electrochemical and optical fluoride sensors

“…As mentioned above, optical fluoride sensors that take advantage of the dimer-monomer equilibrium between Al(III)OEP have been reported in literature [13,14]. The optical sensing film uses the principles of anion/proton co-extraction chemistry to achieve an optical response.…”

“…The other approach involves covalently attaching the Al(III) porphyrins to a polymer backbone. The latter method has been studied by a number of research groups [13][14][15][16]. As reported by Qin and Bakker [17], dimer formation for a chloride ion selective In(III) porphyrin system was eliminated by modifying the metalloporphyrin with a methacrylate functionality to allow attachment within polymethacrylate polymer, and use of that polymer as a macromolecular ionophore agent in conventional PVC membranes.…”