Roles of in situ surface modification in controlling the growth and crystallization of CaCO3 nanoparticles, and their dispersion in polymeric materials

Abstract

The in situ surface modification of inorganic nanoparticles (NPs) and its influence on the size, morphology, and particle surface properties is increasingly receiving attention. Control of the size and morphology and perfect dispersion of inorganic NPs in polymer matrices fabricates soft materials with unique optical, electrical, magnetic, gas barrier, self-healing, and thermal and mechanical properties. This study explores the strategy of the in situ modification of inorganic NPs (CaCO 3 ) with cationic and anionic surfactants and the role of in situ modification on the dispersion of these NPs in thermoplastic polymers (poly e-caprolactone, PCL). The surfactants having an appropriate polar head with a high charge density bind onto the crystal's nuclei, protect them against extensive aggregation, and consequently control the size, morphology, and surface properties of the produced NPs. This permits formulation of hybrid materials with enhanced thermal stability and tensile modulus and with a marked increase of the crystallization rate.

Structure of alumina-silica nanoparticles grafted with alkylphosphonic acids in poly(ethylacrylate) nanocomposites

“…Here we are interested in the formation of covalent bonds, deliberately excluding physisorption of, e.g., surfactant molecules [32] (in particular via ion exchange of clays [33]), from this discussion. Meth et al have studied the structure of charge-stabilized silica NPs in DMF, and formulated nanocomposites with bare NPs in polymethylmethacrylate (PMMA), and with phenyltrimethoxysilanemodified NPs in polystyrene [34].…”

Crystallization of Nano‐Calcium Carbonate: The Influence of Process Parameters

“…Moreover, an intermediate aragonite phase with needlelike shape can also be stabilized depending on the process conditions. In particular, the rate of CaO and CO 2 conversion into ions as well as the Ca 2+ /CO 3 2ratio was considered [11] to affect the growth rate of the crystal faces {104} and {211} in a different way, thus leading to calcite crystals with different morphology. pH 8.6 [4], while a lower pH value resulted in the formation of valerite.…”

“…Although extensively studied, due to the complexity involved in the industrial carbonation process, only a few methods allow for the morphological control of the precipitated calcite without the help of additives which are increasing the production costs and can compromise the purity needed in certain applications [6,9,10]. Beside additives, also the concentration of calcium hydroxide, CO 2 flow rate, Ca 2+ /CO 3 2ratio, temperature, and stirring quality are among the parameters that influence carbonation reaction.…”

“…The same authors reported that an increase in CO 2 flow rate was favorable from the viewpoint of forming platelike calcium carbonate particles. The reason for morphology changes by enhanced dissolution of CO 2 was related to the accumulation of H + , HCO 3 -, and CO 3 2ions that gave rise to diminishing pH values and thus favoring formation of platelike products [12]. In particular, the rate of CaO and CO 2 conversion into ions as well as the Ca 2+ /CO 3 2ratio was considered [11] to affect the growth rate of the crystal faces {104} and {211} in a different way, thus leading to calcite crystals with different morphology.…”

Synthesis of Submicrometer Calcium Carbonate Particles from Inorganic Salts Using Linear Polymers as Crystallization Modifiers

“…1 Although calcium carbonate is an abundant naturally occurring mineral already largely used in the polymer industry, recently the clever manipulation of particle size and its effects on the material properties has attracted considerable attention. [2][3][4][5][6][7][8][9][10][11][12] Nano-and micrometer calcium carbonate particles can be synthesized by a variety of methods, including controlled gas diffusion, colloidal/microemulsion systems, sonochemistry, hydrothermal synthesis, etc. The simplest approach consists of the precipitation of calcium carbonate from solutions containing inorganic salts as a source of calcium(II) and carbonate ions.…”