Rapid synthesis of biocompatible bilayer hydrogels via frontal polymerization

Abstract

Hydrogels have been attracting much attention as smart soft materials. The exploration of methods allowing hydrogels to have anisotropic composition, structure, and properties would benefit the fabrication of smart materials with versatile multi-functions. Here we report the rapid frontal polymerization (FP) of bilayer hydrogels possessing good water swelling, mechanical strength, self-healing, biocompatibility, and antibacterial capabilities. The bilayer hydrogels, consisting of poly(AM-co-AMPS) (G-1) and poly(AM-co-HPA) (G-2) (AM, acrylamide; AMPS, 2-acrylamide-2-methylpropanesulfonic acid; HPA, hydroxypropyl acrylate), are synthesized in one step within 6 minutes (min) by horizontal FP. These polymer hydrogels have hierarchical porous morphology with pore sizes of several micrometers and several hundreds of micrometers respectively, equilibrium swelling ratio up to 3371% in water, tensile strength up to 0.204 MPa, and self-healing ability. The good cytocompatibility and low toxicity of the hydrogels are demonstrated through cell culture of L929 fibroblasts in vitro experiments. The tests of hydrogels with Escherichia coli and Staphylococcus aureus reveal their antibacterial property. The results demonstrate that biocompatible anisotropic hydrogels with versatile functions could be fabricated via the rapid and energy-saving approach of FP.

Polymer Hydrogels and Frontal Polymerization: A Winning Coupling

“…Yang and co-workers [65] succeeded in obtaining frontally polymerized (in horizontal configuration) bi-layered anisotropic hydrogels made of poly(acrylamide-co-2-acrylamide-2-methylpropanesulfonic acid) and poly(acrylamide-co-hydroxypropyl acrylate). For the former layer, the weight ratio between acrylamide and 2-acrylamide-2-methylpropanesulfonic acid was set to 4:1, whereas a 1:1 acrylamide/hydroxypropyl acrylate weight ratio was chosen for the latter.…”

“…Each sample was cut into two separate halves, one of which was dyed; then, the two halves were put together for 24 h at room temperature and finally merged into a complete sample capable of sustaining intense stretching. Reprinted with permission from [65]. Copyright Wiley, 2022.…”

“…Liu and co-workers [66] exploited an interfacial ignited gelation process in order to obtain Ag + /Fe 3+ -poly(acrylic acid), Ag + /Fe 3+ -poly(acrylic acid-co-N,N- Each sample was cut into two separate halves, one of which was dyed; then, the two halves were put together for 24 h at room temperature and finally merged into a complete sample capable of sustaining intense stretching. Reprinted with permission from [65]. Copyright Wiley, 2022.…”

Polymer Hydrogels and Frontal Polymerization: A Winning Coupling

“…Yang and co-workers [57] succeeded in obtaining frontally polymerized (in horizontal configuration) bi-layered anisotropic hydrogels made of poly(acrylamide-co-2-acrylamide-2methylpropanesulfonic acid) and poly(acrylamide-co-hydroxypropyl acrylate). For the former layer, the weight ratio between acrylamide and 2-acrylamide-2-methylpropanesulfonic acid was set at 4:1, whereas a 1:1 acrylamide/hydroxypropyl acrylate weight ratio was chosen for the latter; N,N,N',N'tetramethylethylenediamine was employed as crosslinker.…”

Rapid Preparation of Superabsorbent Self-Healing Hydrogels by Frontal Polymerization

“…Then, FP was developed to prepare various materials including resins, coatings, and foams, as well as functional hydrogels [22,[26][27][28]. In particular, our group developed diverse FP modes to prepare a number of functional hydrogels, such as fluorescent nanocomposite hydrogels, biocompatible hydrogels, stimuli-responsive hydrogels, hydrogel actuators, or self-healing hydrogels [29][30][31][32][33][34][35][36][37][38][39]. Here, we explored new hydrogels with robust properties using the simple and efficient method of FP.…”