Versatile poly(N-vinylcaprolactam)-grafted-hydroxypropyl cellulose polymers with tailored thermo- and pH-responsive properties via sustainable organocatalyzed atom transfer radical polymerization

Dual responsive phase behavior of nonionic cellulose-based polymer brushes by visible-light-driven organocatalyzed atom transfer radical polymerization

Hydroxypropyl cellulose (HPC) is a nonionic, thermo-responsive polymer with temperature-dependent phase behavior. This behavior can be modified by grafting molecular units and polymer brushes onto the cellulose backbone. However, the thermo-response of such modified celluloses under biological and environmental conditions, such as pH, has been scarcely reported. This study details the synthesis and characterization of dual-temperature- and pH-responsive poly(vinyl pyrrolidone)-graft-hydroxypropyl cellulose (PVP-g-HPC) by organocatalyzed visible-light-driven atom transfer radical polymerization (O-ATRP). Employing a "grafting-from" approach, we synthesized a series of PVP-g-HPCs with controlled molecular weight and narrow dispersity. By precisely adjusting the molar ratios of HPC and N-vinyl pyrrolidone, we investigated the changes in the lower critical solution temperature (LCST) under various pH conditions. Our results revealed that the thermo-responsive PVP side chains exhibited a reverse dependence on pH. Additionally, the LCST window of HPC thermo-responsive derivatives was expanded to 37 °C within the physiological pH range.

Thermo-Responsive Polymer-Based Nanoparticles: From Chemical Design to Advanced Applications

Thermo-responsive polymers have emerged as a cutting-edge tool in nanomedicine, paving the way for innovative approaches to targeted drug delivery and advanced therapeutic strategies. These "smart" polymers respond to temperature changes, enabling controlled drug release in pathological environments characterized by high temperatures. By exploiting their unique phase transition, occurring at the lower or upper critical solution temperatures (LCST and UCST), these systems ensure localized therapeutic action, minimizing collateral damage to healthy tissues. The integration of these polymers into nanoparticles with hydrophilic shells and hydrophobic cores enhances their stability and biocompatibility. Furthermore, advanced polymer engineering allows precise modulation of LCST and UCST through adjustments in composition and hydrophilic-lipophilic balance, optimizing their responsiveness for specific applications. In addition to drug delivery, thermo-responsive nanoparticles are gaining attention in several fields such as gene therapy and imaging. Therefore, this review explores the chemical and structural diversity of thermo-responsive nanoparticles, emphasizing their ability to encapsulate and release drugs effectively. Second, this review highlights the potential of thermo-responsive nanoparticles to redefine treatment paradigms, providing a comprehensive understanding of their mechanisms, applications, and future perspectives in biomedical research.

Revolutionizing photocatalysis: Synthesis of innovative poly(N-tertiary-butylacrylamide)-graft-hydroxypropyl cellulose polymers for thermo-responsive applications via metal-free organic photoredox catalysis

In this study, we present a groundbreaking approach utilizing metal-free, visible light-mediated organic photoredox catalyzed atom transfer radical polymerization (O-ATRP) to synthesize cellulose-based stimuli-responsive polymers. Our method resulted in the successful synthesis of innovative metal-free poly(N-tertiary-butylacrylamide)-graft-hydroxypropyl cellulose (PNTBAM-g-HPC) polymers with exceptional control over molecular weight and narrow dispersity index (Đ) and explored their applications in organo-photocatalytic reactions. This approach addresses the limitations of traditional atom transfer radical polymerization method, which suffer from metal contamination and toxicity related problems. O-ATRP and organic photoredox catalysts have been sought to address these difficult challenges. In this study, we synthesized organic compound; 2,4,5,6-tetrakis(diphenylamino)isophthalonitrile (4DPIPN), which served as an organic photoredox catalyst, enabling the synthesis and application study of PNTBAM-g-HPC polymers via organic photoredox catalysis. Furthermore, by employing 4DPIPN, three different types of PNTBAM-g-HPC polymers were synthesized. Through thorough characterization techniques including FTIR, NMR, UV/Visible spectroscopy, TGA, and GPC analysis, we confirmed the successful synthesis of photocatalyst and three different types of PNTBAM-g-HPC polymers under O-ATRP conditions. By adjusting the molar ratios of PNTBAM side chains, we fine-tuned the LCST of HTA-20 polymers to 37.3 °C, demonstrating their thermoresponsive behavior. This synthetic approach shows great potential for applications in biosensors, pharmaceuticals, biomedical engineering, and drug delivery systems.