Thermoresponsive Properties of PNIPAM-Based Hydrogels: Effect of Molecular Architecture and Embedded Gold Nanoparticles

Abstract

Thermoresponsive hydrogels were successfully prepared from poly(N-isopropylacrylamide)-based polymers with different architectures (linear, branched, or hyperbranched). The macromolecular architectures strongly influence the internal structure of the hydrogels, therefore modulating their thermoresponsive and rheological properties. These hydrogels were used for the in situ synthesis of gold nanoparticles. Significant changes in hydrogel microstructures and in average pore size due to the presence of gold nanoparticles were observed. Additionally, their presence significantly increases both the mechanical strength and the toughness of the hydrogel networks.

Effect of copolymer composition of RAFT/MADIX-derived N-vinylcaprolactam/N-vinylpyrrolidone statistical copolymers on their thermoresponsive behavior and hydrogel properties

“…Whatever their overall dimensions, properties of those hydrogels also strongly dependent on their internal structure. 54 Intensive efforts have been made to gain control over it at a nanoscale level. Indeed, finely tuning this structure yields access to materials with improved responsiveness in terms of kinetics and change of dimension.…”

“…A complete different behavior was reported for PNIPAm for which the plateau is reached just few degrees after the transition occurred. 54 This might be related to dehydration phenomenon that in the case of PVCL was described to operate in two steps: at T c a first dehydration occurred leading to the formation of dehydrated zones surrounded by slightly hydrated ones. After Please do not adjust margins T c the latter zones dehydrated progressively up to a fully dehydrated state at 60°C.…”

Morphing in nature and beyond: a review of natural and synthetic shape-changing materials and mechanisms

“…This decreases the space between them, ejecting solvent and losing volume. The temperature at which this occurs may be adjusted by the temperature of processing [145], blending [146] and microstructure [147], in addition to the inclusion of composites which may adjust temperature response through density changes [148], or Joule or surface plasmon resonance heating (see later sections on light, electricity and magnetism for these mechanisms).…”

Dynamic bioengineered hydrogels as scaffolds for advanced stem cell and organoid culture

“…[53] HA, heparin, and PNIPAAm are also used in engineered hydrogels due to their role in biologic signaling, affinity-mediated growth factor release, and thermoresponsive properties, respectively. [54][55][56][57] Cell-adhesive peptide ligands and matrix metalloprotease-degradable crosslinking molecules are ubiquitous features across 3D scaffold design. Notwithstanding the advances in 3D cell culture, it remains somewhat of an art.…”