Temperature‐dependent structure and compressive mechanical behavior of alginate/polyethylene oxide–poly(propylene oxide)–poly(ethylene oxide) hydrogels

Abstract

We report the structural and mechanical behavior of multicomponent hydrogels comprising the commercial poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) block copolymer F127 and alginate. Previous studies on this system have shown thermoreversible behavior in shear rheology. Here we explore the properties of these materials under compression and large deformations, relevant to applications such as wound dressings that require mechanical robustness. For gels with lower F127 concentration, we find that the stiffness of the gels can be ascribed to the alginate network, and that the Young's modulus and fracture stress do not strongly depend on temperatures. However, for gels with an F127 concentration of 30 wt %, the Young's modulus is enhanced at higher temperatures. Under large deformations, the fracture stress and fracture strain of the materials can be independently varied using the alginate and F127 concentrations, respectively; without the trade‐off in these properties that is often observed in rigid polymer networks. Small‐angle X‐ray scattering shows a power‐law dependence scattering intensity on q arising from the alginate network and scattering peaks consistent with rearranging micelles. For gels with lower F127 concentrations, we find a disordered–body‐centered cubic (BCC)‐face‐centered cubic (FCC) progression of states with temperature, and a BCC/FCC mixture for gels with higher F127 concentrations.

The effect of poly(acrylic acid) on temperature‐dependent behaviors and structural evolution of poloxamer 407

“…It is well documented that the spherical micelles probably arise from the assembly of PX unimers in water, and PX micelles become gelation with an ordered discrete cubic arrangement upon heating 5,15,40 . The arrangement of the spherical micelles into FCC arrays or BCC arrays is primarily determined by the nature of the intermicellar repulsive force 45–47 .…”

“…In this regard, the temperature‐dependent gel structures that are constructed from the micelle packing of amphiphilic block copolymers have become attractive 2 . Their nanoscale assembly and corresponding functional properties can be tailored by various strategies, such as a change of the block composition, a modification of the block length, the use of cosolvent, and polymer blending 2,4,5 . Among various strategies, polymer blending is an economically favorable approach for fabricating polymeric materials with new and improved functionalities because this approach can avoid the use of toxic precursors and/or complex synthetic processes 6,7 .…”

“…The average number of ethylene oxide and propylene oxide units varies and depends on each specific type of poloxamer 8 . Among the different types of poloxamers, poloxamer 407 (PX) has been receiving special attention in biomedical and pharmaceutical applications due to its biocompatibility and thermosensitive properties 5,10–12 . PX chains possess higher ethylene oxide in relation to propylene oxide units.…”

Fabrication Strategies Towards Hydrogels for Biomedical Application: Chemical and Mechanical Insights

“…As an example, regarding the latter stimulus, multicomponent hydrogel for wound healing hydrogels composed by block copolymer F127 and alginate has been evaluated. The elastic modulus is 2.9 kPa (at 15 °C) and it becomes 40 and 50 kPa at 25 °C and 40 °C, respectively [148] . Regarding the effect of the molecular weight on the hydrogel N ‐(2‐aminoethyl)maleimide trifluoroacetate salt/hyaluronic acid with different molecular weight hydrogels have been investigated for the regeneration of cartilage tissue by culturing bone marrow‐derived mesenchymal stem cells [149] .…”

“…The elastic modulus is 2.9 kPa (at 15 °C) and it becomes 40 and 50 kPa at 25 °C and 40 °C, respectively. [148] Regarding the effect of the molecular weight on the hydrogel N ‐(2‐aminoethyl)maleimide trifluoroacetate salt/hyaluronic acid with different molecular weight hydrogels have been investigated for the regeneration of cartilage tissue by culturing bone marrow‐derived mesenchymal stem cells. [149] Three hyaluronic acid species with different molecular weights–low (4 kDa), medium (10 kDa), and high (90 kDa) have been selected to regulate the physical hydrogel properties.…”