Concise synthesis of a light/temperature/pH/CO-quadruple responsive azobenzene functionalized homopolymer for reversible photopatterning

A novel light/temperature/pH/CO 2 -quadruple responsive azobenzene functionalized homopolymer of poly[( E )-3,14-dimethyl-13-oxo-6,9,12-trioxa-3-azapentadec-14-en-1-yl 4-(phenyldiazenyl)benzoate] [P(Azo-N-EO 2 MA)] was prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization. The light-responsiveness of P(Azo-N-EO 2 MA) was demonstrated by examining the UV/vis absorption spectra under alternating UV/blue light irradiation or UV irradiation/heating conditions. P(Azo-N-EO 2 MA) has an upper critical solution temperature (UCST) in the co-solvent of n -butanol/water and a critical pH in aqueous solution. The effects of different molecular structures, molecular weights and concentrations on the UCST and critical pH were investigated. The response of P(Azo-N-EO 2 MA) to CO 2 was demonstrated via the cyclic bubbling of CO 2 /N 2 through a solution of P(Azo-N-EO 2 MA). Then, the interaction between the different response was explored. The critical micelle concentration (cmc) of P(Azo-N-EO 2 MA) was tested. Micelles of P(Azo-N-EO 2 MA) were prepared by self-assembly, and the morphology or size of the micelles can be changed by applying acid or irradiating with UV light. Finally, P(Azo-N-EO 2 MA) was applied to the preparation of rewritable paper, and it is proved that the rewritable paper has good cyclability, stability and high resolution during the process of "writing-erasing-writing" of different patterns. P(Azo-N-EO 2 MA) expands the types of multistimuli-responsive homopolymers available to researchers and has good prospects for applications in self-assembly, drug delivery and optical storage. A novel light/temperature/pH/CO 2 -quadruple responsive azobenzene functionalized homopolymer that can be used in optical storage, P(Azo-N-EO 2 MA), has been synthesized and its responses to stimuli are found to be sensitive and reversible.