Formation of BaSO4 Fibres with Morphological Complexity in Aqueous Polymer Solutions

Abstract

BaSO4 fibres with morphological complexity were formed in aqueous solution with polyacrylate and partially monophosphonated poly(ethyleneoxide)-block-poly(methacrylic acid) additives by a simple precipitation reaction. For polyacrylate, formation of the fibrous deposits was strongly dependent on the level of supersaturation (S) and Ba2+:polymer molar ratio (R). At S = 60 to 80, and R = 3 to 14, highly anisotropic crystalline fibres consisting of bundles of BaSO4 nanofilaments were formed after several weeks, although the yield was low. The nanofilaments were also organized into cone-shaped aggregates at S = 80, and at lower R values these formed higher-order structures that consisted of multiple cone-on-cone assemblies with remarkable self-similarity. Increasing the supersaturation produced ovoid or cross-shaped dendritic particles for the range of molar ratios studied. In contrast, BaSO4 crystallisation in the presence of a partially phosphonated block copolymer gave a high yield of BaSO4 fibres up to 100 microm in length, and consisting of co-aligned bundles of 30 nm-diameter defect-free single-crystal nanofilaments with a uniform growth tip. A model for the defect-free growth of BaSO4 nanofilaments in aqueous polymer solutions based on amorphous precursor particles, vectorially directing forces and van der Waals attraction is proposed.

Shape Controlled Synthesis of Barium Carbonate Microclusters and Nanocrystallites using Natural Polysachharide – Gum Acacia

“…The crystallization involves the formation of different hierarchical structures like rods through dumbbell to flower shaped which have never been seen before in natural biominerals. Proteins and polysaccharides with complicated patterns of various functional groups in GA selectively adsorb on to the metal ion thereby hindering the crystal growth, followed by the mesoscale self-assembly of nanometer-scale building block into hierarchial superstructures [38][39][40][41][42]. The key reaction of CO 2 with Ba 2+ ions entrapped within GA polymer leads to the growth of beautiful structures of witherite nanocrystalline, such an aggregated morphology not normally observed using other surfaces as templates.…”

Crystal Splitting in the Growth of Bi2S3

“…Meanwhile, in a strongly related field, bio-inspired morphosynthesis using designed artificial organic templates offers another approach in generating inorganic crystals with unusual structure specialty and complexity [5]. For example, in the case of BaSO 4 , a variety of morphologies including cones, multiple-cones [6], peanuts and flowers with a crystallographically forbidden ten-fold symmetry [7] as well as complex bundles and superstructures [8] have been obtained by utilizing various double hydrophilic block copolymers as crystal modifiers.…”

Calcium phosphate neuron-like structures: a rare case or a common structure?

“…[16][17][18][19] Particularly in the calcium phosphate system, Antonietti et al reported back in 1998 the stabilization of delicate neuron-like calcium phosphate structures with the help of a DHBC consisting of a long poly(ethylene oxide) block and a short poly(methacrylic acid) block partially alkylated with dodecylamine (PEO-block-PMMA-C12). 20 These structures were again replicated by Tjandra et al in 2005 using a similar design of the DHBC (PEO-block-PMMA) but with a longer PMMA chain.…”