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This study is aimed at booming intelligent polymers and their applications in catalysis, presenting an intelligent polymer catalyst with photo-mediated catalytic ability. This catalyst was fabricated with polymeric 2-acrylamide-2-methylpropylsulfonic acid (acidic moieties capable of catalytic hydrolysis) and photo-sensitive acrylamide-azobenzene prepared from the synthesis of 4-aminoazobenzene with acryloyl chloride. Under the radiation of ultraviolet light, this catalyst would undergo a change of cis/trans-conformation of azobenzene, causing alterable accessibility to the internal catalytic sites and as a result mediated catalytic ability. This catalyst presented significant catalytic ability at ambient conditions due to the trans-conformation of azobenzene which endorsed accessibility to the internal catalytic sites. Conversely, this catalyst showed limited catalytic ability under ultraviolet light, in response to the isomerization of the cis-conformation of azobenzene which inhibited the accessibility. In this way, this catalyst showed the photo-mediated catalytic ability. The suggestion of this polymer catalyst provides a prospect to optically modulate the catalytic proceedings, particularly for complicated processes. [ABSTRACT FROM AUTHOR]

Abstract: ‘On/off’-switchable catalysis by a smart enzyme-like imprinted polymer is reported. This unique imprinted polymer was composed of poly(N-isopropylacrylamide)-containing p-nitrophenyl phosphate-imprinted networks that exhibited temperature-dependent hydrophilicity/hydrophobicity. At a relatively low temperature (such as 20°C), this polymer was capable of vigorous catalysis for the hydrolysis of p-nitrophenyl acetate due to its hydrophilic networks, which enabled access to the imprinted framework. On the contrary, at higher temperatures (such as 40°C), this polymer demonstrated poor catalysis resulting from its dramatically increased hydrophobicity, which inhibited access to the imprinted sites. Unlike previously reported imprinted polymers which lack adjustable networks, this novel imprinted polymer employed thermosensitive poly(N-isopropylacrylamide) networks, thus enabling the switchable catalysis. [Copyright &y& Elsevier]

The article presents thermodynamic and kinetic surveys on the specific recognition and catalysis by molecularly imprinted polymer catalysts. Using p-nitrophenyl phosphate as templates and 1-allylimidazole as functional monomers, the imprinted material was prepared. The prepared polymer catalyst shows a highly specific recognition and catalysis toward the imprint species. Kinetic analysis indicates that this specific behavior, in nature, can be a result of a preferential promotion. The specific imprint leads to a larger hydrolysis rate in the imprint species than in its analogue. Thermodynamic study also implies that the molecular induction generating from the imprint to NPA is larger than to its analogue, which thus makes the polymer capable of specifically alluring the imprint species to bind. [ABSTRACT FROM AUTHOR]