Smart molecular brushes
Polymer brushes consist of long chains of molecules attached at one end to a surface, such that the chains stretch away from the anchor point. Although molecular chains are normally entangled, the molecules within polymer brushes are so close together that they repel each other, inducing them to stretch out. Since these chains can be grafted to numerous substrates and alter their structure in response to environmental stimuli, they hold promise for designing smart materials. The EU-funded POLYBRUSH (Dynamics in polymer brush-nanoparticle systems) project developed a model system to better understand how polymer brushes work. Since most applications require polymer brushes to interact with nanoparticles, POLYBRUSH developed a gold nanoparticle-polymer brush system. Researchers first anchored polymer brushes with different properties and chain lengths to a silicon substrate, then analysed their structures using advanced imaging techniques. Next, they adapted the gold nanoparticles to make them more stable when incorporating them into the polymer brushes. Researchers used insulin which contains sulphur atoms that bind strongly to gold. This “insulin capping” made the gold nanoparticles very stable even in harsh conditions. Since the insulin-capped gold nanoparticles are soluble in water, it also makes them very useful for biomedical applications. This study has overcome many challenges that previously prevented scientists from studying the dynamics of these complex systems. Understanding the interactions between nanoparticles and polymer brushes will allow researchers to improve their design for medical, environmental and industrial applications.
Keywords
Smart materials, polymer brush, nanoparticle, gold, insulin capping
