Effect of Charge Density Matching on the Temperature Response of PNIPAAM Block Copolymer–Gold Nanoparticles

• Published in: Journal of physical chemistry. C 2012-06, Vol.116 (23), p.12844-12853
• Main Authors: Volden, Sondre, Eilertsen, Jan Lasse, Singh, Gurvinder, Wang, Wei, Zhu, Kaizheng, Nyström, Bo, Glomm, Wilhelm R
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Electron, ion, and scanning probe microscopy; Exact sciences and technology; Low-dimensional structures (superlattices, quantum well structures, multilayers): structure, and nonelectronic properties; Materials science; Nanocrystalline materials; Nanoscale materials and structures: fabrication and characterization; 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; Scanning probe microscopy: scanning tunneling, atomic force, scanning optical, magnetic force, etc; Structure of solids and liquids; crystallography; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties)
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp300754b

Upon conjugation of thermoresponsive polymers to nanomaterials such as gold nanoparticles (Aunps), whether and to what extent the properties of the polymer-coated Aunps differ from that of the free polymer depends on the interaction between polymer and the nanoparticle scaffold. Here, we studied the interaction between positively charged Aunps and negatively charged poly(N-isopropylacrylamide) (PNIPAAM) copolymers with different sizes of the charged block (poly(3-sulfopropyl methacrylate potassium), PSPMA), as well as the resulting temperature-dependent optical behavior of the polymer nanoconstructs using UV–vis spectroscopy, quartz crystal microbalance with dissipation monitoring (QCM-D), dynamic light scattering (DLS), as well as atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). We demonstrate that by controlling the charge density matching between Aunp and copolymer we can induce gel formation with random inclusion of Aunps, form single monolayer-covered thermoresponsive Au nanostructures, or use the Au nanostructures as branching units to induce gel formation below LCST.