Over the course of the entire project, we performed the following work and achieved the following results.
We developed two classes of signal responsive catalysts: one class where the catalyst is inactivated by being chemically blocked by a protecting group or 'cage', the other class where the catalyst is blocked by being sequestered inside a molecular container. For the latter, we demonstrated that concept for organometallic catalysts as well as organocatalysts. We also extended the concept to enable repeated on/off switching of activity and control over the time-domain of activity by coupling catalyst activity to a chemical reaction network. For the caged catalysts, we demonstrated their application in soft polymer materials (gel formation) and how to make their activation specific to certain chemical signals. We have subsequently worked on coupling catalysis and signal response to chemical reaction networks, to achieve repeated and temporary responses to specific signals. These networks were then coupled to polymer materials such as micelles (nanometer sizes particles) and polymer gels. With those, we showed how signals and catalysis can change material behaviour, for instance in gel contraction, polymer conformation, and gel destruction. We also coupled these types of behaviour to alternative signals such as light and radioactivity. For the combination of catalysis and reaction networks, we developed theoretical models to predict their behaviour. In the context of chemical reaction networks, we discovered a new type of network by surprise, and then explored its use in making signal responsive polymer materials. There, we made polymer gels and particles that can disintegrate in response to slight damage (a case of very efficient signal amplification), gels that can release chemotherapeutics drugs, and injectable gels.
