Characterization of a conjugate between poly(N-vinyl caprolactam) and a triazine-based covalent organic framework as a potential biomaterial

Abstract

Thermoresponsive polymers (TRPs) have been explored over decades for biomedical applications, and poly(N-vinylcaprolactam) (PVCL) TRP is extensively investigated due to its low toxicity and lower critical solution temperature (LCST), close to physiological temperatures. Besides this, the utilization of covalent organic frameworks (COFs), which belong to a class of porous polymers, in bio-based applications is of great interest due to their remarkable properties. Thus, the integration of PVCL and covalent organic frameworks (COFs) as conjugate materials can lead to advanced bio-based applications; however, the need is to understand the influence of the COF on the PVCL conformation. Herein, a triazine-based COF, CC-TAPT-COF, has been synthesized and completely characterized. Later, the effect of CC-TAPT-COF on the PVCL polymer conformation was studied using various techniques. In fluorescence spectroscopy, a fluorescence quenching for PVCL in the presence of CC-TAPT-COF was observed, which indicated conformational changes. Later, results from thermal fluorescence studies and dynamic light scattering as a function of temperature showed a slight decrease in LCST value for PVCL after the addition of CC-TAPT-COF concentrations. These results showed a slight effect of CC-TAPT-COF on the PVCL conformation. Likewise, a slight decrease in the transmittance value for specific bands in infrared spectra showed a slight effect of CC-TAPT-COF on the PVCL conformation. Further, results from electron microscopy and atomic force microscopy revealed a conjugate formation between PVCL and CC-TAPT-COF due to the presence of binding interactions between them. Overall, the results from several studies showed a slight effect of CC-TAPT-COF on the PVCL during conjugate formation between PVCL and CC-TAPT-COF. This study will be beneficial for the development of COF-thermoresponsive polymer conjugates with a mixture of their unique features as advanced biomaterials.