Physical hydrogels composed of polyampholytes demonstrate high toughness and viscoelasticity

Sun, Tao Lin; Kurokawa, Takayuki; Kuroda, Shinya; Ihsan, Abu Bin; Akasaki, Taigo; Sato, Kodai; Haque, Md. Anamul; Nakajima, Tasuku; Gong, Jian Ping

doi:10.1038/nmat3713

Cited by 1,667 publications

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“…Detailed procedures were described in the literature. [21,22] Synthesis of polyelectrolyte hydrogels: As the polyelectrolyte (PE) hydrogels in single network structure are extremely weak, double network (DN) hydrogels were synthesized from 9 the same charged monomer as the first and second network. Such DN structure improves the mechanical strength of the polyelectrolyte gels for some extend.…”

Section: Synthesis Of Neutral Polyampholyte Hydrogelmentioning

confidence: 99%

“…The inter-chain ionic bonds serve as physical crosslinking to form hydrogels. [21] Owing to such dynamic ionic bonding structure, the PA hydrogels show specific properties, such as deswelling in water, strong viscoelasticity, high toughness, and self-healing. [21,22] Beside these bulk properties, the dynamic ionic bonds of PA hydrogels on their surface are expected to create attractive interacting sites through the formation of polarization induced ion-bond complex formation with charged or polar species of counter surfaces, which can initiate the adhesion for physiological surfaces.…”

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“…[21] Owing to such dynamic ionic bonding structure, the PA hydrogels show specific properties, such as deswelling in water, strong viscoelasticity, high toughness, and self-healing. [21,22] Beside these bulk properties, the dynamic ionic bonds of PA hydrogels on their surface are expected to create attractive interacting sites through the formation of polarization induced ion-bond complex formation with charged or polar species of counter surfaces, which can initiate the adhesion for physiological surfaces. According to previous studies, the molecular process of the complex formation is depicted as, when a neutral PA gel approaches a polyelectrolyte (PE) or protein species within their electric double layer, the neutral PA is polarized by the electric field of the polar species, which induces charge redistribution of the PA in such a way that opposite charges to that of polar species head to polar species and vice vasa.…”

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“…This gel is copolymerized from sodium 4-vinyl-benzenesulfonate (NaSS) and (2-acryloyloxyethyl)-trimethylammonium chloride quaternary (DMAEA-Q) with a small amount of chemical crosslinker. [21,22] Different from common hydrogels that usually swell in water to absorb abundant of water after preparation, the PA gel deswells in water by ~ 40 % in volume, and at the equilibrate state it only contains ~ 52 wt% of water as a result of ionic bond formation.The gel is very soft, highly stretchable, and viscoelastic ( Figure S1, Supporting Information). The dynamic mechanical measurement showed a broad peak of loss factor tanδ around 300 rad/s, which gives a characteristic time τ w = 1/300 ≃ 3 ms ( Figure S2, Supporting Information).…”

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Self‐Adjustable Adhesion of Polyampholyte Hydrogels

et al. 2015

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Biological surfaces are very complex in nature. They have wide distribution in molecular species; including positive and negative charges, polar and non-polar groups. [1] A material to show adhesion to such biological surfaces should have the capability of creating enough adhesive interacting sites with these species in wet environment. [2] Conventional hydrogels usually have poor adhesion to biological surfaces. [3] This is because the adhesion in wet environment is usually based on the Columbic interaction that strongly depends on the charge combinations. [3,4] Many of the biological surfaces and hydrogels have net negative surface charge [5] and they are repulsive in water. Developing adhesives that possess the ability of quick, strong, and reversible adhesion to hydrogels and biological tissues regardless their net charge identity will substantially promote the application of hydrogels in biomedical applications. Several research groups have tried to develop different adhesive hydrogels based on surface modification, [6] mechanical interlocking, [7] making composites, [8] supramolecular recognition, [9] and nano-particles. [10,11] But these approaches have limitations in practical applications, such as lengthy and complicated way of processing, lack of water resistivity and universality, inability in non-residual removal, etc. [12] The clue to develop adhesives working for hydrogels and biological tissues hides in nature.Bacteria cells, ubiquitous in environment, can attach with almost any surfaces including human tissues, regardless the diversity in the surface chemistry. The self-adjustable capability of the extracellular polymeric matrix (EPM) of bacteria cells has made this possible. [13,14] EPM can provide sufficient interacting sites for adsorption of species at interface in response to substrates mechanical and chemical properties through re-distribution of their charged groups. [15] Inspired from nature, we intend to find out a self-adjustable hydrogel adhesive for adhesion to hydrogels and tissues. A self-adjustable surface is such a surface which can offer its species for the formation of attractive interaction depending on substrate charges through dynamic reorganization process. A possible design for achieving such a self-adjustable 3 adhesive is a hydrogel composed of both positively and negatively charged monomers.Presence of both charges in the hydrogel is expected to create attractive interacting sites with any charged surfaces regardless of their charge identity to facilitate adsorption. But this seems to be tricky, because incorporation of both type charges in the same hydrogel sometime encounters strong self-ionic association, which will made it impossible for the formation of bonds with other species residing in different surfaces or in some cases imbalance in component inside hydrogel offers a strong net charge over the surface, [16] which will prevent their non-specific adhesion property. We can overcome this problem by choosing a neutral (charge balanced) polyampholyte (PA) hydrogel th...

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Section: Synthesis Of Neutral Polyampholyte Hydrogelmentioning

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