Reversible Calcium(II)‐Ion Binding through an Apparent pK_a Shift of Thermosensitive Block‐Copolymer Micelles

Abstract

There is an increasing need for smart materials capable of removing multivalent ions from aqueous streams without the inconvenience of brine regeneration as in ion-exchange processes. Herein, we present a thermoresponsive micellar system consisting of polystyrene-poly(methoxy diethyleneglycol acrylate) block copolymer surfactants modified with carboxylic acid end groups (PS-PMDEGA-COOH) that can be used to switch between the adsorption and desorption of divalent calcium(II) cations by a mild temperature trigger, thus providing a new type of thermoregenerable ion-adsorbing materials. The switch of calcium(II)-binding capacity is demonstrated to result from a shift in the pKa value of the carboxylic acid groups by the collapse and redissolution of the PMDEGA block and the associated change in local polarity.

A Synthetic, Transiently Thermoresponsive Homopolymer with UCST Behaviour within a Physiologically Relevant Window

“…Stimuli‐responsive polymers, also called “smart polymers”, respond to chemical or physical changes by a change in solution behaviour . This unique property has fuelled interest in these materials for a number of applications, including biomaterials design, separation, catalysis, and sensors . Amongst the most intensively studied stimuli‐responsive polymers are those that exhibit lower critical solution temperature (LCST) behaviour .…”

“…[1][2][3] This unique property has fuelled interest in these materials for an umber of applications, including biomaterials design, separation, catalysis,a nd sensors. [4][5][6][7][8][9] Amongst the most intensively studied stimuliresponsive polymers are those that exhibit lower critical solution temperature (LCST) behaviour. [10,11] Such polymers…”

Multiresponsive Behavior of Functional Poly(p-phenylene vinylene)s in Water

“…Therefore, PDTriG was employed as it has a higher load of carboxylic acid groups. The polymer was solubilized in basic solution so that the carboxylic acid groups were present as carboxylate groups, which are known to bind with calcium(II) ions in a 2:1 fashion [60,61,62]. Upon addition of half an equivalent of calcium(II) ions compared to the carboxylate groups, all polymer precipitated out of solution, ascribed to interpolymer crosslinking by calcium(II)–carboxylate coordination as schematically depicted in Scheme 2.…”

Synthetisch hergestellte, transient thermoresponsive Homopolymere mit einer oberen kritischen Lösungstemperatur für physiologisch relevante Anwendungen

“…Stimuliresponsive Polymere, sogenannte “intelligente Polymere”, können auf einen chemischen oder physikalischen Stimulus hin ihr Löslichkeitsverhalten ändern . Diese Eigenschaft hat großes Interesse dafür geweckt, solche Materialien für biomaterielle Entwicklungen, Trennprozesse, Katalysen oder Sensoren nutzbar zu machen . Zu den am meisten untersuchten stimuliresponsiven Polymeren zählen solche, die eine untere kritische Lösungstemperatur (LCST) aufweisen .…”

“…[1][2][3] Diese Eigenschaft hat großes Interesse dafürg eweckt, solche Materialien fürb iomaterielle Entwicklungen, Trennprozesse,K atalysen oder Sensoren nutzbar zu machen. [4][5][6][7][8][9] Zu den am meisten untersuchten stimuliresponsiven Polymeren zählen solche,d ie eine untere kritische Lçsungstemperatur (LCST) aufweisen. [10,11] Sie sind bei niedriger Te mperatur im Wässrigen lçslich, da sich eine Vielzahl an Wasserstoffbrücken zwischen den Polymeren und den umgebenden Wassermolekülen aufbaut, die eine Polymer-Polymer-Wechselwirkung unterbinden.…”