Assembly Of The Polymer And The Anionic Surfactant-based Materials Synthesis

Biominerialization is the study of the formation, structure and properties of inorganic solids deposited in biological systems. That is, under certain chemical conditions, the inorganic ions in solution are transformed to solid minerals under the specific control of the organic species. Biomimetic or bio-inspired materials chemistry is currently a promising field to synthesize functional inorganic materials. Calcium carbonate, hydroxyapatite and silica are the most common biominerals in nature, and bio-inspired synthesis of those materials would shed light on the study of mechanism of biomineralization, and be significant to the synthesis and design of new functional materials.The interaction between organic and inorganic species controls the growth of inorganic materials, as well as their structures and morphologis. In this thesis, by designing the interactions between the organic species (polymer and anionic surfactant) and the inorganic precursors, different types of silica, calcium carbonate and hydroxyapatite were synthesized. The main content is as follows:1. Anionic polypeptide, the poly(sodium L-glutamate), was applied to fabricate microporous silica hollow nanospheres templated by the secondary structures of the polypeptide as porogens. In the synthesis, 3-aminopropyltrimethoxysilane (APMS) and tetraethyl orthosilicate (TEOS) were used as the silica sources, and the coassembly follows the mechanism of the anionic surfactant–templated mesoporous silica (AMS) through a S?N+?I? pathway, where S indicates the anionic polypeptide, I indicates inorganic precursors (TEOS), and N indicates costructure-directing agent (APMS), which interacted with the negatively charged anionic polypeptide secondary structures electrostatically and cocondensed with silica source to form the silica framework. The product was subjected to characterizations of X-ray diffraction (XRD), infrared spectroscopy (IR), thermogravimetric (TG) analysis, scanning electron microscopy (SEM), transmitted electron microscopy (TEM), and nitrogen adsorption-desorption measurement. It was found that the pH value of the synthesis solution was an important factor to the morphological control of the silica products. Besides the microporous hollow nanospheres, microporous submicron silica solid and hollow spheres were also obtained facilely by changing the synthesis parameters. Our study further implies that anionic polypeptides, which are able to control mineralization of calcium carbonate and calcium phosphate, could also induce silica condensation in the presence of proper silica precursors. It is also expected that functional calcium carbonate (phosphate)/silica–nanocomposite materials would be fabricated under the control of the anionic polypeptide.2. The anionic polymer, poly(acrylic acid) (PAA), was used together with APMS and TEOS as silica source to synthesize composite nanospheres of PAA/silica. The results indicate that after calcination the silica nanospheres is non-porous, and this can be explained by the lack of the secondary structure of the PAA chains if compared with polypeptide chains. Furthermore, it has been proved that addition of organic solvent such as THF would influence the morphology of the products. By introduction of anionic surfactant in the reaction solution, super-microporous silica can be obtained with the BET surface area of 761 m2/g and pore size of 1.2 nm.3. Amphiphilic block copolymers, poly(L-phenylalanine)-b-poly(ethylene glycol), were synthesized and the properties of phase separation, conformation, crystalline property and micro domain motion were subjected to detailed solid state NMR studies. By the methods of 1H CRAMPS and 13C CPMAS TOSS NMR, it was found that with the decreasing of the polypeptide chain length, theα-helix conformation decreased, amorphous structure increased and the crystallinity of PEG chain increased. By 1H spin diffusion NMR the domain size of the amorphous PEG was determined and it was found that with the decreasing of the polypeptide chain length, the domain size of amorphous PEG decreased obviously. The molecular motion in the copolymer was characterized by dipolar filter, double quantum filter, 2D WISE and 2D LG-CP NMR methods. It was found that due to the existence ofα-helix the polypeptide chain is rather rigid, while the motion of the amorphous PEG is fast.4. Poly (γ-benzyl-glutamate)(PBLG) and amphiphilic block copolymers, poly(L-phenylalanine)-b-poly(ethylene glycol), were used to fabricate silica materials by Evaporation-Induced Self-Assembly (EISA) method. In the synthesis procedure, anilino-methyl triethoxy silane (AMTS) was used as an intermedium, i.e., on the one hand it interacts with polypeptide-based copolymer throughπ-πinteraction between the phenyl groups of Phe segments and AMTS; on the other hand, AMTS can co-condense with tetraethoxylsilane (TEOS) through hydrolysis process. The prepared silica possesses supermicropores and it is proposed that the supermicropores are templated by the polypeptide segments. It is proved that both polypeptide-based block copolymer and AMTS play important roles in the formation of mesoscale short-range-order and hierarchical structure. It is noted that PEG45-b-Phe50 can induce a well-defined shuttle-like morphology of polymer/silica hybrid particles.5.N-lauroylsarcosine sodium (Sar-Na) was used to control calcium carbonate crystalization in ethanol or ethanol/water solution at ambient temperature. By means of SEM, XRD and IR, the morphology and structure of the samples were characterized. It was revealed that with increasing the reaction time, the morphology of the CaCO3 particles generally varies from aragonite polyhedron to amorphous calcium carbonate spheres in pure ethanol. In the ethanol/water solution, with increasing the amount of N-lauroylsarcosine sodium, the morphology of the CaCO3 particles varies from flower-like to spheres. Pure vaterite crystals with spheres shape are obtained at n(Ca): n(Sar)=1:2. At a fixed n(Ca): n(Sar) molar ratio of 1:1, with increasing the volume fractions of distilled water, the morphology of the CaCO3 particles varies from flower-like to spheres. By hydrothermal reaction method under the control of N-lauroylsarcosine sodium, single crystal hydroxyapatite nano-plates was synthesized and the different synthesis conditions were carefully studied.