Probing interfacial interactions and dynamics of polymers enclosed in boron nitride nanotubes

Understanding interfacial interactions in polymer systems is crucial for their applicability for instance in adhesives and coatings. Enclosing polymers in a cylindrical volume provides a system for studying interactions dictated by a continuous interfacial layer and a bulk-like volume in the middle of the cylinders. Here, we describe a simple method for enclosing polymers into boron nitride nanotubes (BNNTs) and establishing the effect of the interfacial interactions on the glass transition temperature (T-g) of the polymers by infrared spectroscopy. The volume of the inner channel is large in comparison to the volume of the loaded polymer coils, allowing the polymer to expand along the inner channel, resulting in the effect of interfacial interactions on polymer dynamics dominating over confinement effects. As examples, we loaded poly(4-vinyl pyridine), poly(methyl methacrylate), poly(vinyl pyrrolidone), and poly(disperse red 1 acrylate) in BNNTs. The strongest interaction between the studied polymer and BNNTs was observed for poly(4-vinyl pyridine), which also caused a significant increase of T-g. In addition to characterizing the effect of interfacial interactions on the thermal transitions of the polymers, this method, which is generalizable to most soluble polymer materials, can be used for studying photoinduced transitions in photoactive polymers thanks to the transparency of the BNNTs at visible wavelengths.

Automated summary

Understanding interfacial interactions in polymer systems is crucial for their applicability, and encasing polymers in boron nitride nanotubes allows for studying the effect of these interactions on the glass transition temperature using infrared spectroscopy. The volume of the inner channel in the nanotubes allows for polymer expansion, with different polymers showing varying degrees of interaction with BNNTs and changes in T-g. This method, applicable to most soluble polymer materials, can also be used for studying photoinduced transitions in photoactive polymers due to the transparency of BNNTs at visible wavelengths.