Unconventional Strategy to Anatase TiO2 Nanocrystals with Tunable Surface Chemistry via Liquid Crystalline Polyamides as a Functional Matrix

5 years ago

Unconventional Strategy to Anatase TiO2 Nanocrystals with Tunable Surface Chemistry via Liquid Crystalline Polyamides as a Functional Matrix

Ning You, Chenxi Zhang, Lingli Zhang, Qingxiang Zhao, Zhe Cui, Minying Liu, Xinchang Pang, Peng Fu

An unconventional but robust route to synthesize anatase TiO₂ colloidal nanocrystals with tunable surface chemistry and dimensions was developed via liquid crystalline polyamides (LCPAs) with pyridine rings as a functional matrix. Titanium(IV) tetraisopropoxide (TTIP), as the precursor of TiO₂ nanocrystals, was selectively incorporated into the compartment containing pyridine ring units via a coordination interaction between the pyridine rings and precursors, followed by an in situ direct polycondensation reaction of two monomers with TTIP into amorphous TiO₂ nanoparticles encapsulated into the LCPA matrix. The functional polyamide chains capped on the surface of the TiO₂ nanoparticles can be readily carbonized at 500 °C in inert atmosphere (argon), subsequently with the carbon forming a protecting coating on the surface of TiO₂ nanocrystals to prevent the nanocrystals from aggregating. In addition, the amorphous TiO₂ was simultaneously transformed into anatase TiO₂ after 500 °C calcination. The carbon shell on the surface of anatase TiO₂ nanocrystals can be readily removed by calcination at a relatively low temperature (400 °C) in air. At last, the carboxyl-terminated polymers, such as PMMA–COOH or PEG–COOH, were chosen as functional ligands for the surface modification of anatase TiO₂ nanocrystals to fabricate core@shell anatase TiO₂@polymer colloidal nanocrystals. The sizes of anatase TiO₂ nanocrystals can be also tuned by adjusting the molar ratio of TTIP precursors to pyridine units.

Publisher URL: http://dx.doi.org/10.1021/acs.jpcc.7b08542

DOI: 10.1021/acs.jpcc.7b08542