Synthesis And Applications Of Stimuli-Responsive Degradable Polymers

Stimuli-responsive degradable polymers are able to degrade in response to slight external variations in environmental conditions(light,moisture,pH,and temperature,etc.).Meanwhile,stimuli-responsive degradable polymers also exhibit excellent properties such as light weight,low-cost,easy processability and so on.Thus,they have been extensively utilized in controlled delivery systems,flexible electronics and transient electronics,and biosensing.Among various external triggers,light is a very appealing trigger as it can conveniently offer both temporal and spatial control in a precise manner.On the other hand,moisture is also an intriguing trigger and it is ubiquitous in natural environment.Base on these considerations,we have designed and synthesized three kinds of light/moisture responsive polymers and developed their applications in controlled and triggered delivery systems,flexible electronics,and transient electronics.1.Photodegradable coordination polymer particles(CPPs)formed by infinite coordination polymerization of Zn2+and a photocleavable organic linker containing o-nitrobenzyl derivatives were designed and synthesized.Subsequently,we demonstrated that these photodegradable CPPs are able to efficiently encapsulate cargos for on-command release upon the irradiation of low-power UV light.2.Moisture was successfully used to trigger the degradation of polyanhydride substrates and develop a new type of physically transient electronics.The hydrolysis of polyanhydride in the presence of trace moisture triggers the degradation of inorganic components fabricated on top of the substrate.This unique feature enables the design of transient electronics that are completely different from previous reports and avoid the use of aqueous solutions or biofluids.Various passive and active devices were fabricated on polyanhydride substrates to demonstrate the concept of moisture-triggered transient electronics.3.A photochemical approach toward high-fidelity programmable transfer printing was proposed,suggesting a potentially feasible method for integrating a new technique into current semiconductor processing technologies to fabricate flexible or stretchable electronics.This new transfer printing concept is based on the facile adhesive strength modulation of the polymer adhesive embedded with a photodegradable functional group.High efficiency and high-fidelity transfer printing process can be achieved by employing the stamp coated with photodegradable adhesive.This new triggering mechanism enables methodologies that have not been explored in previous transfer printing,which may also be extended to other forms of heterogeneous materials assembly.