Water-dispersed thermo-responsive boron nitride nanotubes: synthesis and properties

Abstract

In this study, water-dispersed thermo-responsive boron nitride nanotubes (BNNTs) were prepared in a simple two-step process, where on the first step oligoperoxide was grafted via the interaction of amino groups (defects) of BNNTs with pyromellitic chloroanhydride fragments in oligoperoxide molecules. The second step involves N-isopropylacrylamide (NIPAM) graft polymerization 'from the surface' of oligoperoxide-functionalized BNNTs resulting in poly(N-isopropylacrylamide) (PNIPAM) coating. The pristine and functionalized BNNTs were characterized by thermogravimetric analysis, Fourier transform infrared spectroscopy, ultraviolet-visible spectrophotometry, dynamic light scattering, scanning electron microscopy and atomic force microscopy. PNIPAM-functionalized BNNTs exhibit excellent dispersibility in water and possess thermo-responsive properties. The water-dispersion of thermo-responsive PNIPAM-functionalized BNNTs can help their potential use in biomedical applications as 'smart' surfaces, nanotransducers and nanocarriers.

Stability of Halloysite, Imogolite, and Boron Nitride Nanotubes in Solvent Media

“…Nowadays, one of the most interesting procedures for nanomaterial functionalization is to prepare grafted polymer brushes [7,90] (Figure 5a). In this route, the nanotubes are covalently functionalized with polymer brushes through surface polymerization.…”

“…The modified nanotubes displayed high dispersibility in a large number of organic media. In the work of Kalay et al [7], BNNTs functionalized with the thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) were fabricated, and were dispersible in water (Figure 5b). It was also shown that the hydrodynamic radius of these systems decreased two-fold at around 32 • C (Figure 5c).…”

“…In addition, a prospective method to create stabile dispersion in water is the hydroxylation of BNNTs in H 2 O 2 solution for 48 h at 110 • C [86,87]. Adapted from [7].…”

“…Since carbon nanotubes were discovered in 1991 [1], the nanotube structure has garnered interest and has been widely researched in other types of particles, like metal nanotubes [2,3], oxide nanotubes [4,5], boron nitride nanotubes [6,7] and nanotubular clays, to study the characteristics of tunable chemistry, surface area, and porosity.…”

“…Therefore, they can be exploited in the biological field after an appropriate noncovalent [45,46] or covalent [47] modification, which can increase their dispersibility in water. BNNTs were used as smart materials [7], drug [47] and gene delivery systems [48], biomaterials [49], sensory systems [50], as well as hydrogen storage [51]. …”