Triblock Copolymer Micelle-Crosslinked Hydrogels

Abstract

This chapter reviews the preparation, structures, properties, and applications of tough and responsive hydrogels crosslinked by triblock copolymer micelles. An amphiphilic triblock copolymer, Pluronic F127, is functionalized with reactive groups. The functional F127 chains form polyfunctional micelles in aqueous solution, which are used for reaction with hydrophilic monomers or polymer chains to form hydrophobically crosslinked network. Free radical polymerization, host-guest interaction, and dynamic bonds have been utilized to connect the polymer chains with the reactive micelle coronae. The obtained polymer hydrogels show outstanding strength and toughness, with the micelles serving as energy dissipation centers. The structural evolution and energy dissipation mechanisms have been investigated in detail. By incorporating functional monomers into the network, a series of functional hydrogels responsive to pH, salt, electric field, and temperature have been developed. The hydrogels have been utilized as building blocks to fabricate soft actuators, shape-morphing devices, and biomaterials for tissue repair.

Clustering and Hierarchical Organization of 3D Printed Poly(propylene fumarate)-block-PEG-block-poly(propylene fumarate) ABA Triblock Copolymer Hydrogels

“…As reported in the literature for chemically cross-linked hydrogels, the increase in the cross-link density usually results in higher modulus and strength, but the hydrogels become rigid and fragile. 53 Interestingly, as presented in Figure 5C,D, the increasing DP of PPF blocks and consequently the number of cross-linked sites led to a fall in the resistance to breaking and compressive modulus in both copolymer series. On the contrary, the swollen PEG regions allowed building up the stress and similar hydrophilic weight fractions f led to close compressive strength values.…”

“…However, due to better network flexibility, hydrogels containing the longest PEG middle block exhibited higher compression capacity than those containing the shortest PEG (Figure B). As reported in the literature for chemically cross-linked hydrogels, the increase in the cross-link density usually results in higher modulus and strength, but the hydrogels become rigid and fragile . Interestingly, as presented in Figure C,D, the increasing DP of PPF blocks and consequently the number of cross-linked sites led to a fall in the resistance to breaking and compressive modulus in both copolymer series.…”

“…As reported in the literature for chemically crosslinked hydrogels, the increase in crosslink density usually results in higher modulus and strength, but the hydrogels become rigid and fragile. 53 Interestingly, as presented in Figures 5C and 5D Finally, the correlation between the in vitro degradation behavior in PBS and the nanoscale ordering into PPFn-b-PEGm-b-PPFn ABA triblock copolymer hydrogels was investigated by measuring the remaining dry mass (Figure 6A), the water content (Figure 6B) and the swelling ratio (Figure 6C) over 32 days. Due to PPF hydrolysis, some chains were no longer incorporated in the hydrogel network, leading to mass loss.…”

Design of Bio-Conjugated Hydrogels for Regenerative Medicine Applications: From Polymer Scaffold to Biomolecule Choice

“…The most popular block copolymers are composed of di- or triblock domains. Diblock copolymers based on a hydrophilic and a hydrophobic domain generally lead to the gelation of sample at higher wt% concentrations compared to the triblock counterparts [ 86 ]. This behavior is attributed mainly to the intrinsic ability of triblock copolymers to interact both inter- and intramolecularly, leading to an increase of interactions and thus drastically reducing the CGC [ 86 ].…”