Dihydrophilic block copolymers with ionic and nonionic blocks. I. Poly(ethylene oxide)-b-polyglycidol with OP(O)(OH)2, COOH, or SO3H functions: Synthesis and influence for CaCO3 crystallization

Design, Synthesis and Actual Applications of the Polymers Containing Acidic P-OH Fragments: Part 2-Sidechain Phosphorus-Containing Polyacids

Macromolecules containing acidic fragments in side-groups—polyacids—occupy a special place among synthetic polymers. Properties and applications of polyacids are directly related to the chemical structure of macromolecules: the nature of the acidic groups, polymer backbone, and spacers between the main chain and acidic groups. The chemical nature of the phosphorus results in the diversity of acidic >P(O)OH fragments in sidechain phosphorus-containing polyacids (PCPAs) that can be derivatives of phosphoric or phosphinic acids. Sidechain PCPAs have many similarities with other polyacids. However, due to the relatively high acidity of −P(O)(OH)2 fragment, bone and mineral affinity, and biocompatibility, sidechain PCPAs have immense potential for diverse applications. Synthetic approaches to sidechain PCPAs also have their own specifics. All these issues are discussed in the present review.

Linear coordination polymers based on aluminum phosphates: synthesis, crystal structure and morphology

Several aluminum tris(diorganophosphates) have been synthesized and characterized via elemental analysis, NMR, FT-IR and Raman spectroscopy, as well as powder XRD, and SEM. Single-crystal X-ray diffraction studies revealed that the aluminum tris(diethylphosphate) crystal structure comprises two crystallographically nonequivalent catena-Al[O2P(OEt)2]3 chains propagating along the c-axis. Their parallel orientation favors the formation of closely packed hexagonal domains. PXRD data suggest that other homologues have a similar structure, with the interchain distance closely corresponding to the dimensions of organic ligands. They are also susceptible to a reversible dissociation to ionic species under the effect of primary amines. This feature can be utilized for the synthesis of epoxy nanocomposites.

Double hydrophilic polyphosphoester containing copolymers as efficient templating agents for calcium carbonate microparticles

The use of calcium carbonate (CaCO₃) microparticles is becoming more and more attractive in many fields especially in biomedical applications in which the fine tuning of the size, morphology and crystalline form of the CaCO₃ particles is crucial. Although some structuring compounds, like hyaluronic acid, give satisfying results, the control of the particle structure still has to be improved. To this end, we evaluated the CaCO₃ structuring capacity of novel well-defined double hydrophilic block copolymers composed of poly(ethylene oxide) and a polyphosphoester segment with an affinity for calcium like poly(phosphotriester)s bearing pendent carboxylic acids or poly(phosphodiester)s with a negatively charged oxygen atom on each repeating monomer unit. These copolymers were synthesized by a combination of organocatalyzed ring opening polymerization, thiol-yne click chemistry and protection/deprotection methods. The formulation of CaCO₃ particles was then performed in the presence of these block copolymers (i) by the classical chemical pathway involving CaCl₂ and Na₂CO₃ and (ii) by a process based on supercritical carbon dioxide (scCO₂) technology in which CO₃ ^2- ions are generated in aqueous media and react with Ca²⁺ ions. Porous CaCO₃ microspheres composed of vaterite nanocrystals were obtained. Moreover, a clear dependence of the particle size on the structure of the templating agent was emphasized. In this work, we show that the use of the supercritical process and the substitution of hyaluronic acid for a carboxylic acid containing copolymer decreases the size of the CaCO₃ particles by a factor of 6 (∼1.5 μm) while preventing their aggregation.

POLYMERIC NANOMATERIALS IN BIOMINERALIZATION

Hierarchical synthesis of well-defined nanoparticles and structures is one of the challenges in materials science. Conventional methods have limitations in controlling the size of the crystals as well as their orientation. Biominerals have inspired research to explore bottom-up approaches to the design of novel nanomaterials by utilizing polymeric nanomaterials as templates to synthesize nanoparticles with well-defined morphologies and structures. Here in this review, the role of synthetic and natural polymeric nanomaterials with controlled architecture and selected affinities in the design of biomimetic materials over the years are discussed.

Time-resolved SAXS study of the effect of a double hydrophilic block-copolymer on the formation of CaCO3 from a supersaturated salt solution

The effect of a double hydrophilic block-copolymer additive (made of polyaspartic acid and polyethyleneglycol, pAsp(10)-b-PEG(110)) on the initial formation of calcium carbonate from a supersaturated salt solution has been studied in situ by means of time-resolved synchrotron small-angle X-ray scattering (SAXS). A stopped-flow cell was used for rapidly mixing the 20 mM aqueous reactant solutions of calcium chloride and sodium carbonate. In reference measurements without polymer additive the very rapid formation of primary, overall spherical CaCO(3) particles with a radius of ca. 19 nm and a size polydispersity of ca. 26% was observed within the first 10 ms after mixing. A subsequent, very rapid aggregation of these primary particles was evidenced by a distinct upturn of the SAXS intensity at smallest angles. During the aggregation process the size of the primary particles remained unchanged. From an analysis of the absolute scattering intensity the mass density of these particles was determined to 1.9 g/cm(3). From this rather low density it is concluded that those precursor particles are amorphous, which has been confirmed by simultaneous wide-angle X-ray diffraction measurements. Upon adding 200 pm of the block-copolymer no influence on the size, the size polydispersity and morphology of the primary particles, nor on the kinetics of their formation and growth, was found. On the other hand, the subsequent aggregation and precipitation process is considerably slowed down by the additive and smaller aggregates result. The crystalline morphology of the sediment was studied in situ by WAXS ca. 50 min after mixing the reactants. Several diffraction rings could be detected, which indicate that a transformation of the metastable, amorphous precursor particles to randomly oriented vaterite nanocrystallites has taken place. In addition, a few isolated Bragg spots of high intensity were detected, which are attributed to individual, oriented calcite microcrystals that nucleated at the wall of the capillary.

Three-stage switching of surface wetting using phosphate-bearing polymer brushes

Surface initiated polymer brushes containing phosphate side groups have been used to reversibly switch wettability and hydration between three different states.