CdS Quantum Dots Doped Tuning of Deswelling Kinetics of Thermoresponsive Hydrogels Based on Poly(2-(2-methoxyethoxy)ethyl methacrylate)

• Published in: The journal of physical chemistry. B Vol. 117; no. 50; pp. 16292 - 16302
• Main Authors: Patil, Nagaraj, Roy, Saswati Ghosh, Haldar, Ujjal, De, Priyadarsi
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 19.12.2013
• Subjects: Cadmium Compounds - chemistry; Cadmium sulfides; Condensed matter: electronic structure, electrical, magnetic, and optical properties; DDT; Doping; Exact sciences and technology; Hydrogels; Kinetics; Leakage; Methacrylates - chemistry; Microscopy, Electron, Scanning; Networks; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures; Physics; Quantum Dots; Reaction kinetics; Selenium Compounds - chemistry; Impurity density; Swelling; Polymer gels; Quantum dots; Doping; Photoluminescence; Polymerization; Cadmium sulfide; Orientational order; Hydrogen bonds; Nanocomposites; Luminescence quenching; Kinetics; Hydrogel
• ISSN: 1520-6106; 1520-5207
• DOI: 10.1021/jp408164y

Thermoresponsive poly(2-(2-methoxyethoxy)ethyl methacrylate) (PMEO2MA) based hybrid nanocomposite hydrogels (NCH) were synthesized by dispersing preformed cadmium sulfide (CdS) quantum dots (QDs) in the reaction mixture followed by polymerization via reversible addition–fragmentation chain transfer (RAFT) technique. High doping capacity and negligible QDs leakage were observed for hydrophilic QDs doped hydrogels (hpl-NCH) due to H-bonding interactions between QDs and pendant groups of hydrogel network. The hpl-NCH networks showed improved structural/orientational order and swelling ratios with increasing doping concentration compared to the organic hydrogel (OH). Opposite trends were observed for bulk-CdS (NCH-bulk) and 1-dodecanethiol capped CdS (NCH-DDT) doped hydrogels. Swelling induced linear retardance and quenching of photoluminescence (PL) intensity for hydrogels were exploited to study the deswelling kinetics respectively by Mueller matrix polarimetry and solid state fluorimetry, which were further corroborated with gravimetric analysis. For all the NCH, deswelling process significantly decreased with increasing temperature, which followed the order: 30 > 45 > 60 °C. Slower deswelling was observed for NCH-bulk and hpl-NCH compared to the OH, and also with increase in doping concentration due to the formation of skin layer. However, NCH-DDT exhibited accelerated deswelling process and the order was reversed with respect to doping concentration due to DDT mediated enhanced hydrophobic aggregation and water leakage channels created by long hydrophobic free-mobile nature of QDs surface tethered DDT molecules. The presented methodology provides tunable deswelling of PMEO2MA based hydrogels by doping with hydrophilically/hydrophobically modified CdS QDs.