Bonding dissimilar polymer networks in various manufacturing processes

Abstract

Recently developed devices mimic neuromuscular and neurosensory systems by integrating hydrogels and hydrophobic elastomers. While different methods are developed to bond hydrogels with hydrophobic elastomers, it remains a challenge to coat and print various hydrogels and elastomers of arbitrary shapes, in arbitrary sequences, with strong adhesion. Here we report an approach to meet this challenge. We mix silane coupling agents into the precursors of the networks, and tune the kinetics such that, when the networks form, the coupling agents incorporate into the polymer chains, but do not condensate. After a manufacturing step, the coupling agents condensate, add crosslinks inside the networks, and form bonds between the networks. This approach enables independent bonding and manufacturing. We formulate oxygen-tolerant hydrogel resins for spinning, printing, and coating in the open air. We find that thin elastomer coatings enable hydrogels to sustain high temperatures without boiling.

3D Printing of Multifunctional Hydrogels

“…The tough hydrogel is composed of two types of cross-linked polymer: ionically crosslinked Carbomer and covalently cross-linked PAAm (Figure 3b). [43] Figure 3a shows that Young's modulus of DN hydrogel is much higher than the single network hydrogel. [42] By contrast, PAAm chains form a network through covalent crosslinks.…”

Photodetachable Adhesion

“…[1] Many recent advances involve adhesives for soft and wet materials in medicine and engineering. [13][14][15][16] On-demand detachment is also important in many applications. [13][14][15][16] On-demand detachment is also important in many applications.…”

“…[13][14][15][16] On-demand detachment is also important in many applications. [21][22][23] Strong adhesion usually requires covalent bonds, [14,16,24] physical interactions, [25][26][27] or their combinations. For expensive or vulnerable adherends, the adhesion must be removed without harming the adherends.…”

Multifunctional “Hydrogel Skins” on Diverse Polymers with Arbitrary Shapes

“…Another common strategy involves coating hydrogel layers on the surfaces of devices, owing to hydrogels' favorable similarities with biological tissues in mechanical and chemical properties . Given its straightforward but effective nature, interfacial bonding between the hydrogels and the polymer substrates has been one of the most widely utilized strategies to introduce soft hydrogel coatings on diverse polymer devices . In this approach, hydrogel coatings are typically introduced to the polymer devices either in form of solid preformed crosslinked networks or liquid pregel solutions that are then cured on the surface .…”

“…Given its straightforward but effective nature, interfacial bonding between the hydrogels and the polymer substrates has been one of the most widely utilized strategies to introduce soft hydrogel coatings on diverse polymer devices . In this approach, hydrogel coatings are typically introduced to the polymer devices either in form of solid preformed crosslinked networks or liquid pregel solutions that are then cured on the surface . Recent advances in robust interfacial bonding between tough hydrogels and diverse polymers have enabled hydrogel coatings with improved mechanical robustness, solving previously existing issues of poor hydrogel–substrate adhesion and poor mechanical properties of common hydrogels.…”