Synthesis, Morphology, and Rheological Evaluation of HPMA (-2-Hydroxypropyl Methacrylamide)-PCL (Polycaprolactone) Conjugates.

The design, synthesis, and physicochemical characterization of conjugates are arduous and tedious processes. Several synthetic pathways for polymeric conjugation have been reported; however, conjugation through monomers with suitable reaction conditions can be a simple and robust approach. In the present study, three different conjugates of hydrophilic -2-hydroxypropyl methacrylamide (HPMA) and hydrophobic polycaprolactone (PCL) were synthesized. The followed synthetic pathway not only was simple and robust but also reduced the overall synthetic steps as well as harsh reaction conditions significantly. In a nutshell, three conjugates, i.e., -2-hydroxypropyl methacrylamide and polycaprolactone (HP-PCL), -butanol-polycaprolactone--2-hydroxypropyl methacrylamide (nBu-PCL-HP), and isoamyl alcohol-polycaprolactone--2-hydroxypropyl methacrylamide (ISAL-PCL-HP), were synthesized through this simple synthetic strategy following the monomer conjugation approach along with exhaustive spectroscopic and rheological characterization. The conjugates HP-PCL, nBu-PCL-HP, and ISAL-PCL-HP were characterized by Fourier transform infrared (FT-IR) and NMR (C and H) spectroscopies. The size and ζ potential of conjugates were determined through the dynamic light scattering (DLS) method. The nBu-PCL-HP conjugate displayed a hexagonal-like shape, as evidenced by scanning electron microscopy (SEM) with an obtained size of 237.9 ± 0.21 nm. X-ray diffraction (XRD) analysis proved the crystalline nature of nBu-PCL-HP conjugates. The results of smartly synthesized conjugates intrigued us to study their flow properties in detail. Rheological evaluation resulted in their non-Newtonian type of flow with the best-fit behavior for all of the conjugates followed as per the Herschel-Bulkley and power-law models applied herein. Conclusively, the synthesized HPMA and PCL conjugates may have applications in the preparation of blends, fibers, etc. in the future. The study portrayed that the explored synthetic scheme using monomers and initiators could be a suitable approach for the synthesis of HPMA and PCL conjugates.