We report the preparation of thermoresponsive graphene nanosheets functionalized by the polymer brushes. This approach involves the direct growth of thermoresponsive polymer brushes from functional graphene sheets (FGSs) by chemical modification with initiators followed by extension with poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) through surface-initiated atom transfer radical polymerization. The highly controllable polymerization method affords the hybrid FGS-PDMAEMA with tailorable length of PDMAEMA brushes possessing the average molecular weight (Mn) ranging from 7.4 × 103 to 6.0 × 104 with low molecular weight distributions (Mw/Mn = 1.09-1.22). The resulting FGS-PDMAEMA was carefully characterized with a number of techniques, including elemental analysis, thermogravimetric analysis, differential scanning calorimetry, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy, all supporting the successful integration of polymer brushes onto the surface of FGS. Most importantly, we accomplished the reversible phase transfer of this hybrid FGS-PDMAEMA between aqueous and organic phases via temperature control by taking advantage of the thermoresponsive nature of PDMAEMA brushes. Moreover, the composite film prepared by depositing the suspensions of FGS-PDMAEMA demonstrated the facile control over the wettability upon temperature changes. This tailored control over dispersion in water, selective solubilization between aqueous and organic solvents, and wettability control upon temperature variation have a significant impact on the ability to improve properties of hybrid graphene-based materials. Because of the highly versatile and tunable properties of surface-initiated atom transfer polymerization, we anticipate that the general concept presented here offers a unique potential platform for integrating responsive polymers for graphene nanosheets for advanced electronic, energy, and sensor applications.
Bibliographical noteFunding Information:
This work was supported by the Priority Research Center Program ( 2009-0093818 ), and Basic Science Research Program ( 2011-0004822 ) through the National Research Foundation of Korea funded by the Ministry of Education, Science, and Technology of Korea. This research was also supported by WCU (World Class University) program through the Korea Science and Engineering Foundation funded by the Ministry of Education, Science and Technology ( R31-2008-000-20012-0 ) and by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) ( 2010-0003219 ).
All Science Journal Classification (ASJC) codes
- Organic Chemistry
- Polymers and Plastics
- Materials Chemistry