Calcium carbonate microparticle templates using a PHOS-b-PMAA double hydrophilic copolymer

Hydrophobic Composites Designed by a Nonwoven Cellulose-Based Material and Polymer/CaCO3 Patterns with Biomedical Applications

Herein, we report a simple method to obtain hydrophobic surfaces by surface modification with calcium carbonate via diffusion-controlled crystallization using a cheap, versatile, and super-hydrophilic cellulose-based nonwoven material (NWM) as the substrate. To control the CaCO₃ crystal growth, the ammonium carbonate diffusion method was applied in the presence of polyanions [poly(acid acrylic), poly(2-acrylamido-2-methylpropanesulfonic acid), and a copolymer which contains 55 mol % 2-acrylamido-2-methylpropanesulfonic acid and 45 mol % acrylic acid] or nonstoichiometric polyelectrolyte complexes with polycations [poly(allylamine hydrochloride) and chitosan] on a pristine NWM and on polycation-treated surfaces. The surface morphology obtained by calcite growth under surface or environmental functional groups' influence and the hydrophilic/hydrophobic character of the composite materials were followed and compared to that of the starting material. The obtained composite materials become hydrophobic, having a contact angle in the range of 110-135°. The capacity of tetracycline sorption and release by selected modified surfaces were followed and compared to the untreated NWM. Also, the biological properties were evaluated in terms of biocompatibility, antibacterial activity, and antifouling capability.

Autotemplate Microcapsules of CaCO3/Pectin and Nonstoichiometric Complexes as Sustained Tetracycline Hydrochloride Delivery Carriers

New types of composites were obtained by an autotemplate method for assembling hollow CaCO₃ capsules by using pH-sensitive polymers. Five pectin samples, which differ in the methylation degree and/or amide content, and some nonstoichiometric polyelectrolyte complex dispersions, prepared with the pectin samples and poly(allylamine hydrochloride), were used to control the crystal growth. The morphology of the composites was investigated by scanning electron microscopy, and the polymorphs characteristics were investigated by FTIR spectroscopy. The presence of the polymer in the composite particles was evidenced by X-ray photoelectron spectroscopy, particle charge density, and zeta-potential. The new CaCO₃/pectin hollow capsules were tested as a possible matrix for a tetracycline hydrochloride carrier. The kinetics of the drug release mechanism was followed using Higuchi and Korsmeyer-Peppas mathematical models.

Superparamagnetic Composites Based on Ionic Resin Beads/CaCO3 /Magnetite

The preparation of superparamagnetic composites obtained by CaCO₃ mineralization from supersaturate aqueous solutions is presented. The preparation was conducted in the presence of oleic acid stabilized magnetite nanoparticles as a water-based magnetic fluid and insoluble templates as gel-like cross-linked polymeric beads. The presence of the magnetic particles in the composites provides a facile way for external manipulation using a permanent magnet, thus allowing the separation and extraction of magnetically modified materials. Two ion exchangers based on divinylbenzene/ethyl acrylate/acrylonitrile cross-linked copolymer-a cation ion exchanger (CIE) and an amphoteric ion exchanger (AIE)-were used, as well as different addition orders of magnetite and CaCO₃ crystals growth precursors. The morphology of the composites was investigated by SEM, the polymorphs content by X-ray diffraction, and the thermal stability by thermogravimetric analysis. Polymer, CaCO₃ , and magnetite in the composite particles were shown to be present by energy dispersive X-ray (EDX), XPS, and TEM. The sorption capacity for Cu^II ions was tested, as compared to samples prepared without magnetite.

Composite materials based on poly(N-isopropylacrylamide-co-methacrylic acid) hydrogels and calcium carbonate

The synthesis of complex functional materials with thermo- and pH-sensitive tunable properties based on poly( N-isopropylacrylamide- co-methacrylic acid) hydrogels with different porosities and pH-sensitive and biocompatible calcium carbonate (CaCO3) was investigated. To control the composites characteristics, two hydrogles with the same chemical composition but different porosities were used, as well as different methods for crystal growth, namely, the adding protocol of inorganic partners (rapid mixing or alternate dipping) or the carbonate source. The morphology of the new composites was investigated by scanning electron microscopy and the polymorphs content by Fourier transform infrared spectroscopy, as compared to unmodified hydrogels. Information on the interface between organic/inorganic materials, the radii of gyration of the scattering objects, their fractal dimension, and CaCO3 porosity characteristics were obtained by small-angle X-ray scattering.