Temperature-Dependent Rheological and Viscoelastic Investigation of a Poly(2-methyl-2-oxazoline)-b-poly(2-iso-butyl-2-oxazoline)-b-poly(2-methyl-2-oxazoline)-Based Thermogelling Hydrogel

Abstract

The synthesis and characterization of an ABA triblock copolymer based on hydrophilic poly(2-methyl-2-oxazoline) (pMeOx) blocks A and a modestly hydrophobic poly(2-iso-butyl-2-oxazoline) (piBuOx) block B is described. Aqueous polymer solutions were prepared at different concentrations (1–20 wt %) and their thermogelling capability using visual observation was investigated at different temperatures ranging from 5 to 80 °C. As only a 20 wt % solution was found to undergo thermogelation, this concentration was investigated in more detail regarding its temperature-dependent viscoelastic profile utilizing various modes (strain or temperature sweep). The prepared hydrogels from this particular ABA triblock copolymer have interesting rheological and viscoelastic properties, such as reversible thermogelling and shear thinning, and may be used as bioink, which was supported by its very low cytotoxicity and initial printing experiments using the hydrogels. However, the soft character and low yield stress of the gels do not allow real 3D printing at this point.

Improving printability of a thermoresponsive hydrogel biomaterial ink by nanoclay addition

“…2a). According to our previous study, when the block copolymer solution is above its critical gelation concentration (20 wt%), sol-gel transition will occur at a critical gelation temperature (T gel ) [37,38]. Similarly, the prepared PMeOx-b-PnPrOzi/clay sols showed reversible thermogelation ( Fig.…”

“…Alternatively, two different thermoresponsive hydrogels formed by POx ABAtype triblock copolymers were described. One features hydrophilic PMeOx A-blocks and a hydrophobic poly(2-iso-butyl-2-oxazoline) B-block; the other comprises thermoresponsive outer A-blocks of poly(2-n-propyl-2-oxazoline) and a more hydrophilic poly(2-ethyl-2-oxazoline) inner B-block, respectively [38,39]. However, it is challenging to print real 3-dimensional constructs at this point, even at a relatively high polymer concentration.…”

Improving Printability of a Thermoresponsive Hydrogel Biomaterial Ink by Nanoclay Addition

“…According to our previous study, when the block copolymer solution is above its critical gelation concentration (20 wt.%), sol-gel transition will occur at a critical gelation temperature (Tgel). [37][38] Similarly, the prepared PMeOx-b-PnPrOzi/clay sols showed reversible thermogelation (Figure 2b; Video S1, Supporting Information). To illustrate the fast in situ thermogelation and injectability of PMeOx-b-PnPrOzi/clay hydrogel, we pipetted it into a water reservoir (37 °C), and found that clear hydrogel strands formed immediately after injecting into the water (Figure 2c; Video S2, Supporting Information).…”

“…One features hydrophilic PMeOx A-blocks and a hydrophobic poly(2-iso-butyl-2-oxazoline) B-block, the other comprises thermoresponsive outer A blocks of poly(2-n-propyl-2-oxazoline) and a more hydrophilic poly(2-ethyl-2-oxazoline) inner B block, respectively. [38][39] However, it is challenging to print real 3-dimensional constructs at this point, even at a relatively high polymer concentration. This is due to suboptimal rheological properties, in particular a low yield point, which allows multilayers to fuse more easily and results in poor shape fidelity.…”

Smart Non-Woven Fiber Mats with Light-Induced Sensing Capability

“…Smart systems belong to the group of materials capable of changing the basic properties, when they are exposed to external stimuli such as electric [1][2][3], magnetic [4,5], thermal [6,7], pH [8,9], or light [10,11]. In case of light stimulation, such smart systems can exhibit the shape [12] or resistivity [13] change or generate electric output [14].…”