Thermo‐Induced Double Phase Transition Behavior of Physically Cross‐Linked Hydrogels Based on Oligo(ethylene glycol) methacrylates

Abstract

Double thermosensitive clay/P(MEO 2 MA -co-POEGMA) nanocomposite (NC) hydrogels are prepared by in situ free radical polymerization of 2-(2-methoxyethoxy) ethyl methacrylate (MEO 2 MA) and oligo(ethylene glycol) methacrylate (OEGMA) in the presence of physical crosslinker clay. The temperature-induced phase transition behavior of NC hydrogels is investigated by turbidity, temperature dependent nuclear magnetic resonance, and variable temperature Fourier transform infrared spectroscopy. 2D infrared analysis is employed to study the sequential order of changes of all groups in NC hydrogels during the heating and cooling process. The obtained novel clay/P(MEO 2 MA -co-POEGMA) NC hydrogels exhibit an unusual thermally induced multistep aggregation process and successively undergo three consecutive microstructural changes: "loose clay/polymer microaggregation ↔ homogeneous network structure ↔ dense clay/polymer macroaggregation." Dynamic light scattering and transmission electron microscopy measurements show similar results of the NC nanogel at the same temperature regions, confi rming the three consecutive microstructural changes. This new generation of thermosensitive hydrogel offers promising potential for applications as smart devices, biomedical materials, and drug carriers.

Thermoresponsive Three‐Stage Optical Modulation of a Self‐Healing Composite Hydrogel

“…By adjusting the concentration of the PNIPAM nanogels, we can fine‐tune the transparent point between 15 °C and 30 °C to guarantee enough sunlight transmittance into a building. Such PAH/PNIPAM composite hydrogels show similar double volume phase transition temperatures with the clay/P(MEO 2 MA‐ co ‐OEGMA) hydrogels reported by Zhu and his co‐workers . Herein, the usage amount of PNIPAM nanogel is much less than that of clay and also much easier to be dispersed in the polymer.…”

“…The same windows exhibit transparency in the normal daytime, but become translucent to block sunlight at higher temperatures. A three‐stage transition system of optical modulation has been investigated by Zhu and his co‐workers before . They introduced inorganic cross‐linker clay into the co‐polymer of 2‐(2‐methoxyethoxy) ethyl methacrylate (MEO 2 MA) and oligo (ethylene glycol) methacrylate(OEGMA).…”

Hydrogels with Dual Thermoresponsive Mechanical Performance

“…Hydrogels with opposite temperature behavior were also elaborated using a single copolymer constituted by ethylene oxide oligomonomers of different lengths, i.e., di(ethylene oxide) (EO 2 ) and oligo(ethylene oxide) (EO [8][9] ) physically crosslinked with clay particles. [19,20] The transition temperature of this copolymer, analogue to the poly(ethylene oxide) (PEO) and representing an alternative to PNIPAm, can be tuned in a broad range of temperature by changing the ratio of ethylene oxide oligomonomers. The authors claim that the UCST and LCST behavior is due to the formation of loose and dense polymer/clay aggregates at low and high temperature respectively.…”

A Novel NIR Laser Switched Nanocomposite Hydrogel as Remote Stimuli Smart Valve

“…As Figure a,b shows, comparing with the controlled group, the diameter of CuS NC hydrogel was remarkably shrunk after NIR irradiation for 300 s. In addition, the microstructure of CuS NC hydrogels was more compact than controlled group. This phenomenon reveals that, after NIR irradiation, the homogeneously dispersed CuS induced thoroughly the “coil‐to‐globe” transition of P(MEO 2 MA‐ co ‐OEGMA) chain, and the network of hydrogel shrunk to form a dense microstructure . Conversely, porous structure was formed in the controlled group because insufficient Δ T was not able to induce the “coil‐to‐globe” transition of P(MEO 2 MA‐ co ‐OEGMA) completely.…”

“…Recently, poly(2‐(2‐methoxyethoxy) ethyl methacrylate) (PMEO 2 MA) copolymerizing oligo(ethylene glycol) methacrylate (OEGMA) monomers have been considered as a delicate class of thermal sensitive hydrogels to replace PNIPAM, because the phase transition temperature can be well tuned from 25 to 90 °C by simply regulating the ratio of PMEO 2 MA and OEGMA . Therefore, P(MEO 2 MA‐ co ‐OEGMA) based microgel has been utilized as NIR‐switched drug delivery system, as temperature for drug release can be well regulated in a tissue‐suitable range.…”