Design,synthesis, And Controlled Catalytic Properties Of The Shape Memory Polymer Reactors

Catalyst plays key role in the industry of chemical synthesis. Metal nanoparticles, as an active component of catalyst, has a incomparable advantage due to the high specific surface area. However, the catalytic performance of bare metal nanoparticles may decrease rapidly owing to their aggregation during the catalytic process(especially for liquid catalytic reaction). Traditional supported nanocatalyts may prevent the aggregation of the nanoparticle to improve their catalytic activity. Nevertheless, the realization of controlling the catalytic reactions is still challengeable. Thus, the design and synthesis of new type carrier of metal nanoparticles catalyst to control and regulation the catalytic reaction process have become the target of researchers in recent years.The development of smart polymer reactors, represented by using poly(N-isopropylacrylamide)(PNIPAm) as the support of metal nanoparticles,has offered opportunities to achieve this objective. However,such smart polymer reactors cannot be used in some practical applications, mainly because the furnishing of smart polymer carrier has been proven to be difficult,which is unable to meet the requirements of the diversity of chemical reactions. In addition, it is complicated and challenging to identify the PNIPAms’ hydrophilic and/or hydrophobic properties during the catalytic process.What’s more,it can not meet the goal of selective catalytic performance. Inspired by the method of bionic design, this study overcomes this situation radically.In this study, we reported a polymer microreactor with catalytic performance and self-modulate properties, which was made of nickel nanoparticles and a unique shape-memory polymer consisting of poly acrylic acid and 2-nonenoic acid side chains that exhibited switchable domains. This reactor showed weak reactivity at relatively low temperaturesdue to the low mobility of molecular chains in the switchable domains, which inhibited the access of substrate to the encapsulated nickel nanoparticles. While high catalytic activity, arising from the relative balance between the mobility of molecular chains and the hydrophobicity in the switchabledomains, was observed in this reactor at high temperatures. In this way, this polymer microreactor demonstrated the autonomic " on-off " catalytic ability.In addition, this article has also subtly introduced molecular imprinting technology to creat a shape memory polymer reactor with selective catalytic performance,which was make up by three parts--silver nanoparticles, a unique shape-memory polymer consisting of poly acrylic acid and 10-hydroxydec-2-enoic acid side chains that exhibited switchable domains,and 4-nitrobenzyl alcohol as template.This nanoreactor showed selective catalytic ability at relatively low temperatures due to the "frozen" molecular chains, which allowed forming substrate-selective access to the encapsulated metal nanoparticles. In contrast, this nanoreactor provided non-selective catalysis at relatively high temperatures, arising from the increased mobility of these molecular chains, which resulted in dismantling of the selective access. In this way, this nanoreactor demonstrated the selectivity-switchable catalytic ability.