Hydrogels from Amorphous Calcium Carbonate and Polyacrylic Acid: Bio‐Inspired Materials for “Mineral Plastics”

Abstract

Given increasing environmental issues due to the large usage of non biodegradable plastics based on petroleum, new plastic materials, which are economic, environmentally friendly, and recyclable are in high demand. One feasible strategy is the bio inspired synthesis of mineral based hybrid materials. Herein we report a facile route for an amorphous CaCO 3 (ACC) based hydrogel consisting of very small ACC nanoparticles physically cross linked by poly(acrylic acid). The hydrogel is shapeable, stretchable, and self healable. Upon drying, the hydrogel forms free standing, rigid, and transparent objects with remarkable mechanical performance. By swelling in water, the material can completely recover the initial hydrogel state. As a matrix, thermochromism can also be easily introduced. The present hybrid hydrogel may represent a new class of plastic materials, the "mineral plastics".

Water: How Does It Influence the CaCO3 Formation?

“…[130] Sulfonate groups have al ower affinity towards Ca 2+ than carboxylic groups such that the influence of sulfonate-containing additives such as PSS on the ACCformation kinetics [131] and their stability against crystallization [112] is weaker than that of carboxy-containing counterparts,s uch as PA A. Thea ttractive interaction between these additives and Ca 2+ also leads to the formation of additive-Ca 2+ complexes with aw ell-defined morphology.F or example,the presence of PA AinCa 2+ -containing solutions leads to the formation of crosslinked Ca-PAA polymer networks,a s shown in Figure 10 A. [174,175] Similarly,the presence of PSS in Ca 2+containing solutions leads to the formation of spherical globules,a ss hown in Figure 10 B. [174,175] Similarly,the presence of PSS in Ca 2+containing solutions leads to the formation of spherical globules,a ss hown in Figure 10 B.…”

On Mineral Retrosynthesis of a Complex Biogenic Scaffold

“…Since this feature specifically emerges in the presence of PAA of higher molar mass, the relation between additive molar mass and the properties of intermediate amorphous phases, such as stability and size distribution, appears critical for the emergence of superstructures. Previous studies indicate that the molar mass of PAA is an important determinant of the liquid-or gel-like form of amorphous intermediates [55,56], suggesting corresponding effects on the shape and structure of subsequently-formed mineral products. An interesting feature of phase transitions associated with the mineral precursor is identified for mineralization on the inner membrane surface, i.e., devoid of mammillae ( Figure 9C,D).…”

“…Technically applied as a scale inhibitor, PAA is known to interact with soluble pre-nucleation clusters and inhibit the nucleation of mineral particles [52]. PAA interacts with transient mineral precursors and can stabilize amorphous forms of CaCO3 in a potent manner [52][53][54][55][56][57]. Retro-mineralization of the egg shell scaffold in the presence of PAA provides several insights into the mineralization process ( Figure 6).…”

Spontaneously Regenerative Tough Hydrogels

“…Presented here is a spongeinspired self-regenerative powder from a double-network (DN) tough hydrogel. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] Existing self-healing strategies based on either dynamic covalent or physical bonds have certain limitations. The powderhydrogel-powder cycle can be repeated multiple times with little loss in mechanical properties, analogous to the regeneration of sponges.…”

“…[4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] Existing self-healing strategies based on either dynamic covalent or physical bonds have certain limitations. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] Existing self-healing strategies based on either dynamic covalent or physical bonds have certain limitations.…”