Mechanical properties of temperature sensitive microgel/polyacrylamide composite hydrogels—from soft to hard fillers

Abstract

In this study we investigated the mechanical properties of composite hydrogels based on a polyacrylamide (PAAm) matrix with embedded temperature sensitive poly(N-isopropylacrylamide) (PNiPAM) microgels. We analysed the mechanical properties of the composite material with tensile tests, shear and cavitation rheology. The results of the different experiments displayed an enhancement of mechanical stability with increasing concentration of incorporated microgels. The improved stability is related to an increase of physical cross-linking points due to the incorporation of the microgels. The incorporation of temperature responsive microgel particles introduces temperature sensitive mechanical behaviour of the composite hydrogels. The collapse of the microgels inside the polyacrylamide matrix leads to a change of the volume of the filler particles as well as to a change from a soft filler to a hard filler. The influence of the hard particles on the mechanical stability of the matrix is much stronger which leads to materials with enhanced mechanical properties at high temperatures.

Effect of Sludge Conditioning Temperature on the Thickening and Dewatering Performance of Polymers

“…At 20 g/kg DS, which was the optimum dose for the temperatures lower than 50°C, the zeta potential value was approximately -1.5 mV. With increasing temperatures, the binding between the polymer and sludge particles weakens and the efficiency of flocculation decreases [21]. Therefore, more polymer is needed to achieve the same level of conditioning and flocculation at higher temperatures.…”

Multifunctional magnetic-responsive hydrogels to engineer tendon-to-bone interface

“…[112] In contrary, crosslinking MPs directly to the matrix would enhance the mechanical properties of the system, transforming a rather soft, brittle hydrogel into an elastomeric material that upon a magnetic field stimulation, may quickly deform with no heat evolution or exhaustion. [113] Magnetic hydrogel matrices with tunable properties like stiffness, degree of wettability or even surface functionalization with bioactive molecules, are interesting templates aiming to achieve specific cell or tissue response for TERM applications.…”

Photopolymerizable nanogels as macromolecular precursors to covalently crosslinked water-based networks

“…Examples include reducing polymerization-induced shrinkage stress in dental resins 15 , forming reinforced double-network hydrogels 16,17 , developing thermally responsive composite materials 18,19 , and controlled release in cell-laden hydrogels 20,21 . In these systems the nanogel (or microgel) component content typically reaches as high as 40% by weight.…”