# pH-Responsive Hollow Polymeric Microspheres from Irradiated Cyclic Ether Aqueous Solution
## 4 Conclusions  
A green, simple, and one-step template-free procedure for the construction of pH-responsive hollow microspheres via \(\gamma\)-irradiation was developed using cyclic ethers, such as DCH18C6 and tetrahydropyrane, as monomers in aqueous solution. The hollow microspheres were prepared from radiation-induced polymerization and self-organization of amphiphilic polymers micelles obtained by irradiating cyclic ethers aqueous solution. The pH-responsive delivery ability and reversible morphology transition between micelles and hollow microspheres made the obtained hollow microspheres applicable as advanced functional materials with controlled structure. It is expected that our work will highlight the importance of \(\gamma\)-irradiation in the design and construction of novel'smart' materials via a simple template-free method. Figure 3: The TEM image of the core-shell aggregates obtained from the disassembly of the hollow microspheres in 1 mol L\({}^{-1}\) KOH aqueous solution (the inset of 3a is the CLSM image of the hollow microspheres in 1 mol L\({}^{-1}\) KOH aqueous solution) (**a**), and the SEM and CLSM (the inset of 3b) images of the hollow microspheres obtained by irradiating core-shell am-DCH18C6 for 56 h after removing KOH (**b**). **Supplementary Materials:** The following are available online at [[https://www.mdpi.com/article/10.3390/app11188652/s1](https://www.mdpi.com/article/10.3390/app11188652/s1)]([https://www.mdpi.com/article/10.3390/app11188652/s1](https://www.mdpi.com/article/10.3390/app11188652/s1)), Figure S1: The SEM image (**a**), size distribution (**b**) and the CLSM optical micrograph (**c**) of the well-defined hollow microspheres obtained by irradiating 0.01 mol L\({}^{-1}\) DCH18C6 aqueous solution for 278 h, Figure S2: Micro-FTIR spectra of DCH18C6 and the polymer microspheres obtained by irradiating 0.01 mol L\({}^{-1}\) DCH18C6 aqueous solution for 167 h (3430 cm\({}^{-1}\) OH stretching vibration, 2930 cm\({}^{-1}\) CH\({}_{2}\) asymmetric stretching vibration, 2850 cm\({}^{-1}\) CH\({}_{2}\) symmetric stretching vibration, 1710 cm\({}^{-1}\) C=O stretching vibration, 1660 cm\({}^{-1}\) C=C stretching vibration, 1100 cm\({}^{-1}\) C-O asymmetric stretching vibration, 1000-650 cm\({}^{-1}\) C-H deformation vibration), Figure S3: \({}^{1}\)H NMR spectrum of the amphiphilic polymers obtained by irradiating 0.01 mol L\({}^{-1}\) DCH18C6 aqueous solution. The inset is \({}^{1}\)H NMR spectrum in the range of 8.5-13.5 ppm, Figure S4: XPS spectrum of the hollow microspheres obtained by irradiating 0.01 mol L\({}^{-1}\) DCH18C6 aqueous solution for 167 h, Figure S5: The SEM image (**a**) and size distribution (**b**) of the well-defined hollow microspheres obtained by irradiating 0.01 mol L\({}^{-1}\) tetrahydropyrane aqueous solution for 167 h, Figure S6: The size distribution of the core-shell am-DCH18C6 micelles obtained from the disassembly of the hollow microspheres obtained by irradiating 0.01 mol L\({}^{-1}\) DCH18C6 aqueous solution for 167 h in 1 mol L\({}^{-1}\) KOH aqueous solution, Figure S7: The size distribution of the hollow microspheres obtained by reassembling core-shell am-DCH18C6 after 56 h of irradiation. **Author Contributions:** Conceptualization, J.P. and M.Z. ; methodology, C.Y. ; validation, J.L. ; formal analysis, C.Y. ; investigation, C.Y. ; data curation, C.Y. and J.L. ; writing--original draft preparation, C.Y. ; writing--review and editing, J.P. and M.Z. ; supervision, J.P. All authors have read and agreed to the published version of the manuscript. **Funding:** This research was funded by National Natural Science Foundation of China (NNSFC), Project No.21073008. **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Not applicable. **Data Availability Statement:** Data are included in the article. Additional data are available upon request. **Acknowledgments:** The measurements of CLSM were performed at the Analytical Instrumentation Center of Peking University. The help from PKUAIC ([PERSON]) is acknowledged.