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Biomaterials such as seashells are intriguing due to their remarkable properties, including their hierarchical structure from the nanometer to the micro- or even macroscopic scale. Transferring this nanostructure to generate nanostructured polymers can improve their electrical conductivity. Here, we present the synthesis of polypyrrole using waste seashell powder as a template to prepare a polypyrrole/CaCO 3 composite material. Various synthesis parameters were optimized to produce a composite material with an electrical conductivity of 2.1 × 10 -4 ± 3.2 × 10 -5 S/cm. This work presents the transformation of waste seashells into sustainable, electronically conductive materials and their application as an antistatic agent in polymers. The requirements of an antistatic material were met for a safety shoe sole.

Bio-inspired LAPONITE® (clay)-liquid crystal (LC) polymer composite materials with high clay fractions (>80%) and a high level of orientation of the clay platelets, i.e. with structural features similar to the ones found in natural nacre, have been shown to exhibit a promising behavior in the context of reduced oxygen transmission. Key characteristics of these bio-inspired composite materials are their high inorganic content, high level of exfoliation and orientation of the clay platelets, and the use of a LC polymer forming the organic matrix in between the LAPONITE® particles. Each single feature may be beneficial to increase the materials gas barrier property rendering this composite a promising system with advantageous barrier capacities. In this detailed study, LAPONITE®/LC polymer composite coatings with different clay loadings were investigated regarding their oxygen transmission rate. The obtained gas barrier performance was linked to the quality, respective LAPONITE® content and the underlying composite micro- and nanostructure of the coatings. Most efficient oxygen barrier properties were observed for composite coatings with 83% LAPONITE® loading that exhibit a structure similar to sheet-like nacre. Further on, advantageous mechanical properties of these LAPONITE®/LC polymer composites reported previously give rise to a multifunctional composite system.

Biomimetic composite materials consisting of vanadium pentoxide (V2O5) and a liquid crystal (LC) "gluing" polymer were manufactured exhibiting six structural levels of hierarchy, formed through LC phases. The organic matrix was a polyoxazoline with pendant cholesteryl and carboxyl units, forming a lyotropic phase with the same structural orientation extending up to hundreds of micrometers upon shearing, and binding to V2O5 via hydrogen bridges. Composites consisting of V2O5-LC polymer hybrid fibers with a pronounced layered structuring were obtained. The V2O5-LC polymer hybrid fibers consist of aligned V2O5 ribbons, composed of self-assembled V2O5 sheets, encasing a chiral nematic polymer matrix. The structures of the V2O5-LC polymer composites strongly depend on the preparation method, i.e., the phase-transfer method from aqueous to organic medium, in which the polymer forms LC phases. Notably, highly defined micro- and nanostructures were obtained when initiating the synthesis using V2O5 tactoids with preoriented nanoparticle building units, even when using isotropic V2O5 dispersions. Shear-induced hierarchical structuring of the composites was observed, as characterized from the millimeter and micrometer down to the nanometer length scales using complementary optical and electron microscopy, SAXS, μCT, and mechanical nanoindentation.

Biomimetic organic-inorganic composite materials were fabricated via one-step self-organization on three hierarchical levels. The organic component was a polyoxazoline with pendent cholesteryl and carboxyl (N-Boc-protected amino acid) side chains that was able to form a chiral nematic lyotropic phase and bind to positively charged inorganic faces of Laponite. The Laponite particles formed a mesocrystalline arrangement within the liquid-crystal (LC) polymer phase upon shearing a viscous dispersion of Laponite nanoparticles and LC polymer in DMF. Complementary analytical and mechanical characterization techniques (AUC, POM, TEM, SEM, SAXS, μCT, and nanoindentation) covering the millimeter, micrometer, and nanometer length scales reveal the hierarchical structures and properties of the composite materials consisting of different ratios of Laponite nanoparticles and liquid-crystalline polymer.

Conducting polymers are interesting materials of technological applications, while the use of polymers as additives controlling crystal nucleation and growth is a fast growing research field. In the present article, we make a first step in combining both topics and report the effect of conducting polymer derivatives, which are based on carboxylated polyanilines (c-PANIs), on in vitro CaCO3 crystallization by the Kitano and gas diffusion method. This is the first example of the mineralization control of CaCO3 by a rigid carboxylated polymer. Both the concentration of c-PANI and the presence of carboxylate groups have a strong influence on the CaCO3 crystallization behavior and crystal morphology. X-ray diffraction (XRD) analysis shows crystalline calcite particles confirmed by FTIR spectra. pH and Ca2+ measurements during CaCO3 crystallization utilizing the Kitano and a constant-pH approach show a defined nucleation period of CaCO3 particles. The measurements allow for the calculation of the supersaturation time development, and the kinetic data can be combined with time-dependent light microscopy. The presence of c-PANIs delays the time of nucleation indicative of calcite nucleation inhibition. Microscopy illustrates the morphologies of CaCO3 crystals at all crystallization stages, from homogeneous spherical amorphous CaCO3 (ACC) particles corresponding to the first steps of crystallization to transition stage calcite crystals also involving a dissolution-recrystallization process in a late stage of crystallization. The data show that it is not possible to conclude the crystallization mechanism even for a very simple additive controlled crystallization process without time-resolved microscopic data supplemented by the analysis of the species present in the solution. Finally, fluorescence analysis indicates that conducting polymer derivatives can be incorporated into precipitated calcite particles. This gives rise to CaCO3 particles with novel and interesting optical properties.

Two double-hydrophilic block copolymers, each comprising a nonionic block and an anionic block comprising pendent aromatic sulfonate groups, were used as additives to modify the crystallization of CaCO3. Marked morphological changes in the CaCO3 particles were observed depending on the reaction conditions used. A poly(ethylene oxide)-b-poly(sodium 4-styrenesulfonate) diblock copolymer was particularly versatile in effecting a morphological change in calcite particles, and a continuous structural transition in the product particles from polycrystalline to mesocrystal to single crystal was observed with variation in the calcium concentration. The existence of this structural sequence provides unique insight into the mechanism of polymer-mediated crystallization. We propose that it reflects continuity in the crystallization mechanism itself, spanning the limits from nonoriented aggregation of nanoparticles to classical ion-by-ion growth. The various pathways to polycrystalline, mesocrystal, and single-crystal particles, which had previously been considered to be distinct, therefore all form part of a unifying crystallization framework based on the aggregation of precursor subunits.

In this article, we present a systematic, controlled synthesis of water-dispersed, polymer-stabilized Au nanoparticles with different sizes by either self-reduction or ultraviolet (UV) irradiation-enhanced reduction in the presence of double hydrophilic block copolymers with different functional patterns. The morphology of the particles was found to be spherical, triangular, truncated triangular, and hexagonal under various conditions. In addition, both the particle size and shape could be controlled by variation of the functional group pattern of the block copolymers. With a hexacyclen functional block, we achieved a perfect match to the Au (111) face, resulting in extremely thin free-standing triangular and hexagonal nanoplatelets that show interference patterns in the electron beam due to deformations in the sub-Angstrom range. UV-visible spectra show that the plasmon absorption band can be fine tuned, depending on the type of the polymer and the irradiation power. The influence of the functional polymer groups and the irradiation on the formation of gold nanoparticles was investigated in more detail.

Analytical ultracentrifugation (AUC) is a classical polymer and colloid analysis technique invented by Theodor Svedberg 100 years ago. Modern hard- and software and powerful computers make it now possible to develop the methodology beyond what was possible with this technique before. This perspective aims to describe new possibilities, which extend the possibilities of AUC beyond the classical repertoire of the determination of distributions of sedimentation coefficient, particle size, and molar mass as well as stoichiometries and interaction constants of interacting systems. High-resolution simultaneous characterization of particle size and optical property distributions, investigation of nucleation by reaction in the AUC cell, characterization of particle interactions at a very high concentration, and characterization of complex fluids or osmotic pressures over large concentration ranges even crossing phase boundaries are among the discussed topics. They show that even after 100 years of successful application, AUC still has much yet unexplored potential in colloid and polymer science. This perspective paper spans from the days of invention of analytical ultracentrifugation to now including nonmainstream methodology and instrumentation, which has a huge potential for the future. This includes multiwavelength detectors, high-resolution particle size distributions, chemical reactions in the ultracentrifuge, high-concentration work, osmotic pressure distributions, and characterization of complex fluids. [ABSTRACT FROM AUTHOR]

Post‐polymerization modification provides an elegant way to introduce chemical functionalities onto macromolecules to produce tailor‐made materials with superior properties. This concept was adapted to well‐defined block copolymers of the poly(2‐oxazoline) family and demonstrated the large potential of these macromolecules as universal toolkit for numerous applications. Triblock copolymers with separated water‐soluble, alkyne‐ and alkene‐containing segments were synthesized and orthogonally modified with various low‐molecular weight functional molecules by copper(I)‐catalyzed azide‐alkyne cycloaddition (CuAAC) and thiol‐ene (TE) click reactions, respectively. Representative toolkit polymers were used for the synthesis of gold, iron oxide and silica nanoparticles. [ABSTRACT FROM AUTHOR]

Self-assembled peptide–polymer nanotapes of poly(ethylene oxide)–peptide conjugates are modified by a simple amine–azide transfer to create azide-containing nanofibres, which provide a platform for modular functionalization as demonstrated by the introduction of different carboxyl bearing entities to modulate the calcium binding properties of the nanotapes. [ABSTRACT FROM AUTHOR]

The formation of a polymer protection layer around fragile mineral architectures ensures that structures stay intact even after treatments that would normally destroy them going along with a total loss of textural information. Here we present a strategy to preserve the shape of silica-carbonate biomorphs with polymers. This method converts non-hybrid inorganic-inorganic composite materials such a silica/carbonate biomorphs into hybrid organic/carbonate composite materials similar to biominerals. [ABSTRACT FROM AUTHOR]

This article focuses on mesocrystals and morphology change of CaCO3 crystals in the presence of a polyelectrolyte additive. Crystallization control is one of the most important techniques of preparation, purification, and application of solid substances, making it an intensely studied field. Besides conventional crystallization, there are also nonclassical pathways of crystallization via colloidal intermediates and mesoscale transformation, in which crystalline structures are constructed and/or transformed from larger units instead of single ions. The authors present a simple system of calcite paired with polystyrene sulfonate, which undergoes mesocrystal formation. Appropriate concentration adjustment of both partners allows broad, systematic variation of the mesocrystal morphology that demonstrates long-range interactions. Moreover, the authors reports that selective coding of nanocrystal surfaces by polymers can not only lead to mesocrystals exposing unusual crystal faces in their superstructure, but also can form self-assembled structures with changed symmetry.

Abstract: The synthesis and folding behavior of two different series of double hydrophilic block copolymers based on polyethyleneglycol and short acidic polypeptide blocks are described. The employment of those species in the crystallization of CaCO3 and BaSO4 shows that in contrast to the expectations from biomineral examples, a random conformation of the peptide is more advantageous in mineralization control than an α-helical arrangement of the same chain, which is contradictory to the epitaxial adsorption model in biomineralization. Otherwise, the peptide block copolymers support formation of superstructures similar to those already reported, e.g. well-defined spherical, prolate, and dumbbell morphologies are found. [Copyright &y& Elsevier]

This work focuses on the investigation of ongoing processes in the pre- and postnucleation stage of C-S-H precipitation at pH 12 and pH 13. Calcium induces the condensation of smaller silicate species to bigger oligomers in the prenucleation stage. By titration in combination with ion-selective electrodes, the effects of additives on the formation of C-S-H can be monitored and quantified in terms of calcium binding, nucleation times, supersaturation, and the post-nucleation behavior showing detailed differences between polymers. Negatively charged polymers inhibit nucleation, neutral or almost neutral polymers do not have an influence on nucleation time and supersaturation and the rare promotion of nucleation has been identified with cationic polymers. The post-nucleation data show the polymer influence on solubility and C/S ratio of the precipitated phase and stabilization of primary nucleated particles against further aggregation or growth. This work can be regarded as a step towards better control of C-S-H precipitation. [ABSTRACT FROM AUTHOR]

An efficient synthesis of a methacrylate-based, second-generation (G2) dendronized macromonomer and its free radical polymerization to the corresponding high-molar-mass G2 dendronized polymer are described. The molar mass is determined by gel permeation chromatography (GPC), light- scattering, and analytical ultracentrifugation and compared with values estimated from a scanning force microscopy (SFM) contour lengths analysis of individualized polymer strands on mica. The polymer carries terminal tert-butyl-protected carboxyl groups, the degree of deprotection of which with trifluoroacetic acid is quantified by NMR spectroscopy using the highest molar mass sample. SFM imaging of both protected (noncharged) and unprotected (charged) dendronized polymers on solid substrates reveals mostly linear chains but also some with main-chain branches. The nature of these branches is investigated and the degree roughly estimated to which they are formed. Finally, a synthetic model experiment is described which sheds some light on the aspect of whether chain transfer, a process that could lead to covalent branching, is of importance in the synthesis of the present dendronized polymers. [ABSTRACT FROM AUTHOR]

Homogeneous transparent hybrid films consisting of chitosan (CHI), poly(monomethyl itaconate) (PMMI) and silica were obtained indicating the absence of microphase separation. These ternary hybrid materials are very interesting since materials with high functionality can be obtained presenting different properties from those of the starting materials but with the advantage of preserving the inherent property of each component. The inorganic phase was prepared by sol–gel process of tetraethoxysilane (TEOS). Most of the amine groups from CHI (pKb 7.7) are quaternized in the acidic medium used in the preparations (pH=2), where a physical crosslinking via hydrogen bonding could occur through carboxyl groups from PMMI. Silica gel obtained from TEOS has been intercalated as a very fine dispersion in the polymer complex formed between CHI and PMMI. Transmission electron microscopy and atomic force microscopy was used to examine the homogeneity of the ternary polymer hybrids (CHI/PMMI/SiO2), obtained as self-supported films. The results support the nanometer scale dispersion of the phases. Porous silica films with high BET area were obtained by calcination of the hybrid films. The mean pore diameter of these silica films corresponds to the dimension of the polymer domains observed in the pristine hybrid films. Moreover, it was found that the swelling behavior of the samples was influenced by the organic and inorganic phases, where the inorganic phase tends to diminish the swelling. [Copyright &y& Elsevier]