Three-Component Porous-Carbon-Titania Nanocomposites through Self-Assembly of ABCBA Block Terpolymers with Titania Sols

We report the first use of a block terpolymer for the synthesis of three-component nanocomposites. Here, the use of three chemically distinct polymer blocks enabled control over each of the three final components: partially graphitic carbon, crystalline transition metal oxide, and porosity. Tuning of the individual block lengths and block fractions resulted in control over the three components. Specifically, two PAN-b-PEO-b-PPO-b-PEO-b-PAN pentablock terpolymers were synthesized starting with a functionalized P123 or F127 macroinitiator. The PEO blocks were selectively swelled with titania sols while the PPO primarily served as a mesoporosity source and the PAN served as a carbon source with high yield. Two subsequent heat treatments were used to form partially graphitic carbon which acted as an in situ hard template preserving themesostructure through the crystallization of the titania sols. TEMand SAXSanalysis revealed wormlike microphase separation. Nitrogen physisorption analysis revealed that the pore size distributions for all nanocomposites were narrow and the distribution centers were tuned from 6.0 to 16.5 nm. The carbon content of the nanocomposites was varied from 11.3 to 35.2 wt % by increasing the fraction of PAN in the hybrids.