Search

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]

A large number of species in nature demonstrate switchable responsiveness to external stimuli, which is essential for their adaptation to the changing environment. Inspired by the responsive properties in nature, researchers have made significant progress in the field of synthetic stimuli-responsive materials over the years, particularly in the field of smart polymer catalysts which are able to control the catalytic processes. Here, we review these bio-inspired polymer materials and their applications in self-controlled catalytic processes. Other issues involved in developing these bio-inspired polymer materials including the origin, mechanisms, switchable behaviors and merits are also discussed. [ABSTRACT FROM AUTHOR]

The study is aimed at the present challenge in tandem catalysis, addressing how to achieve tandem catalytic ability and meantime to avoid a mutual engagement between the tandem processes. This objective was met by constituting a nanoreactor with bio-inspired compartments made of core-and-shell architectures. The core-and-shell architectures allowed the nanoreactor to spatiotemporally separate the tandem catalytic processes from each other, in virtue of the restriction from mass transfer and the radial distribution of reaction loci. The shell in this nanoreactor admitted a precursor reaction while the core was responsible the following reaction. There was no mutual engagement in the tandem processes, due to the spatiotemporally-driven sequential catalysis in the nanoreactor. In this way, this nanoreactor demonstrated the "undisturbed" tandem catalytic ability. Differing from reported nanoreactors and bi-functional catalysts which often involve a mutual competition and even cross-reactions between the tandem processes, this nanoreactor may partition the tandem catalytic processes and avoid the mutual engagement. The constitution of this nanoreactor suggests a prospect to develop "undisturbed" tandem catalysts for complicated catalytic processes. [ABSTRACT FROM AUTHOR]

This study was aimed at addressing the present challenge in self-controlled catalysts, about how to furnish the catalysts with self-governed catalytic ability in water. This objective was met by constructing a polymer composite reactor inspired from marine mussels, made of an aquatically autonomous polymer and encapsulated metal nanoparticles. The aquatically autonomous properties at the polymer support, in combination with the catalytic ability of metal nanoparticles, allowed the reactor to run catalysis with aquatically ‘autonomous’ access, which led to the occurrence of aquatically self-governed catalytic ability. This reactor showed poor catalytic reactivity in water at relatively low temperatures due to the ‘closed’ polymeric networks, which blocked access to the encapsulated metal nanoparticles. This reactor showed, however, significant reactivity in water at relatively high temperatures in response to the ‘openness’ of the access. Unlike the switchable catalysis at reported catalytic reactors which usually involved conventional hydrophilic/hydrophobic transition and the leaching of metal nanoparticles, the switchable catalysis at this reactor ran naturally with the aquatically autonomous access that did not involve any hydrophilic/hydrophobic transition and the leaching of metal nanoparticles. This protocol suggested opportunities for developing robust smart catalysts for aquatic chemical processes. [ABSTRACT FROM AUTHOR]

The realization of selective/nonselective-switchable catalytic ability remains a significant challenge in controlled catalytic processes. We herein report an originally-designed imprinted polymer nanoreactor capable of meeting this challenge. This nanoreactor was composed of Ag nanoparticles and a unique holothurian-inspired imprinted polymer carrier that contained mobile molecular chains. These mobile molecular chains, by motioning and lying motionless, enabled the imprinted carrier to function in an 'online/offline'-shiftable paradigm, causing switchable access to the encapsulated metal nanoparticles. This nanoreactor showed selective catalytic ability at relatively low temperatures due to the 'frozen' molecular chains, which allowed for substrate-selective access to the encapsulated metal nanoparticles (i.e., imprinted carrier's 'online' status). In contrast, this nanoreactor provided non-selective catalysis at relatively high temperatures in response to the increased mobility of these molecular chains, which resulted in dismantling the selective access (i.e., imprinted carrier's 'offline' status). Unlike reported imprinted polymer nanoreactors which simply provide selective catalysis, this novel nanoreactor allows selective/nonselective-switchable catalysis in virtue of the bio-inspired design. This study opens up opportunities to modulate catalytic selectivity for controlled chemical processes. [ABSTRACT FROM AUTHOR]