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The application of atypical experimental methods such as conductivity measurements, optical microscopy, and nonstirred polymerizations to investigations of the ‘classical’ batch ab initio emulsion polymerization of styrene revealed astonishing facts. The most important result is the discovery of spontaneous emulsification leading to monomer droplets even in the quiescent styrene in water system. These monomer droplets with a size between a few and some hundreds of nanometers, which are formed by spontaneous emulsification as soon as styrene and water are brought into contact, have a strong influence on the particle nucleation, the particle morphology, and the swelling of the particles. Experimental results confirm that micelles of low-molecular-weight surfactants are not a major locus of particle nucleation. Brownian dynamics simulations show that the capture of matter by the particles strongly depends on the polymer volume fraction and the size of the captured species (primary free radicals, oligomers, single monomer molecules, or clusters).

This study describes the effects of nitrilotriacetic acid (NTA) and ethylenediaminotetraacetic acid (EDTA) on the mineralization of calcium phosphate from bulk aqueous solution. Mineralization was performed between pH 6 and 9 and with NTA or EDTA concentrations of 0, 5, 10, and 15 mM. X-ray diffraction and infrared spectroscopy show that at low pH, mainly brushite precipitates and at higher pH, mostly hydroxyapatite forms. Both additives alter the morphology of the precipitates. Without additive, brushite precipitates as large plates. With NTA, the morphology changes to an unusual rod-like shape. With EDTA, the edges of the particles are rounded and disk-like particles form. Conductivity and pH measurements suggest that the final products form through several intermediate steps.

The properties of amphiphilic triblock copolymer particles, which consist of a hydrophobic polystyrene (PS) core and a thermo-sensitive double hydrophilic block copolymer shell made of polyacrylic acid (PAA) and poly-N-isopropylacrylamide (PNIPAM) sequences, differ significantly depending on the sequence of the hydrophilic blocks from the core to the shell—either PS-PNIPAM-PAA or PS-PAA-PNIPAM. These triblock copolymer particles were prepared via reversible addition-fragmentation chain transfer polymerization (RAFT) following the PISA approach, using the corresponding double hydrophilic block copolymer macro-RAFT agents. The macro-RAFT agents (MRA) were synthesized through sequential polymerization of the corresponding monomers, using 4-cyano-4-(propylsulfonyl thiocarbonyl) sulfonyl pentanoic acid as the RAFT agent. These two different MRAs result in remarkable differences in the course of styrene emulsion polymerization (EP). Furthermore, the two types of polystyrene latexes behave differently in two key aspects: firstly, in terms of particle size and latex stability, which depend on both temperature and ionic strength, and secondly, in their capacity to disperse laponite disks within the particle shell when present during styrene emulsion polymerization.

The assumption that during emulsion polymerization, the monomer molecules simply diffuse through the aqueous phase into the latex particles is a commonplace. However, there are experimental hints that this might not be that easy. Here, simulation results are discussed based on Fick’s diffusion laws regarding the swelling of latex particles. The results of quantitative application of these laws for swelling of latex particles allow the conclusion that the instantaneous replenishment of the consumed monomer during emulsion polymerization requires a close contact between the monomer and the polymer particles.

Morphosynthesis strategies inspired by biomineralization processes gives access to a wide range of fascinating and useful crystalline mesostructures 1 , 2 , 3 . Biomimetic synthesis of inorganic materials with complex shapes can now be used to control the nucleation, tensorial growth, and alignment of inorganic crystals in a way previously not practicable 3 . Double hydrophilic block copolymers (DHBCs) 4 consisting of a hydrophilic block strongly interacting with inorganic minerals, and a non-interacting hydrophilic block, were recently introduced for the control of mineralization reactions. DHBCs are 'improved versions' of the previously used polyelectrolytes or amphiphiles and are extraordinarily effective in crystallization control 5 , 6 , 7 , 8 , 9 . Here, we report on the formation of helices of achiral BaCO 3 nanocrystals in the presence of a racemic DHBC suggesting that a helical alignment can be induced by racemic polymers through selective adsorption on the (110) face of nanocrystals. This mechanism is the key for a better understanding of the self-assembly of chiral organic–inorganic superstructures that don't follow a direct template route.

Poly(terephthalamide) microcapsules can be reproducibly and easily prepared by interfacial polycondensation around emulsion droplets in water. Oil drops of cyclohexane/chloroform mixture stabilized with poly(vinyl alcohol) containing terephthaloylchloride serve as soft template. The interfacial polycondensation starts immediately after addition of an amine mixture (hexamethylenediamine/diethylenetriamine). Light and scanning electron microscopy prove the formation of capsules with size distribution in the range from a few up to 100 µm depending on particular composition of the reaction mixture. The morphology of the capsule wall is characterized by precipitated particles. If instead of pure organic solvents a reactive oil phase is used as template, the capsules can serve in subsequent reactions as templates for the synthesis of composite particles. In this way, styrene can be radically polymerized inside the capsule leading to composite capsules. The capsule morphology is determined by the partition of all components between all phases.

A comprehensive experimental study of aqueous heterophase homopolymerization of 2-hydroxyetyl methacrylate revealed special conditions that must be fulfilled in order to obtain stable latex particles in the nanometer size range. The results clearly show that the formation and the stability of this kind of hydrophilic latex particle strongly depends on the hydrophobic-hydrophilic properties of both the initiating radicals and the stabilizers. Hydrophobic initiators in combination with sodium alkyl sulfate surfactants of proper chain lengths or ionic surface-active initiators lead to stable latex particles. In the latter case the particles keep their identity and spherical shape even after drying of the aqueous dispersion.[PUBLICATION ABSTRACT]

The production of composite polyamide-polystyrene microcapsules by successive polycondensation and radical polymerization is easily possible in a one-pot multi-step reaction. The first step is the emulsification of the template oil phase that contains terephthaloylchloride, styrene monomer, if necessary a cyclohexane-chloroform mixture, and the oil-soluble radical initiator in an aqueous poly(vinyl alcohol) solution. Then, the polyamide capsule formation (second step) is started by the addition of an aqueous diamine solution at 25 °C. Subsequently, the radical polymerization (third step) is initiated by raising the temperature. The morphology of the composite capsules depends strongly on the amount of styrene monomer in the oil mixture and the nature of the initiator. Interestingly, the styrene conversion is much lower if water-soluble initiators are used.

We are presenting a new method to study the swelling of gels by following the apparent weight increase during confined swelling. This method, compared to other procedures, is characterized by its simplicity and versatility to study the influence of the experimental conditions such as composition of the swelling agent and temperature. Examples are given for poly(acrylic acid) and poly( N -isopropyl acrylamide) hydrogels and the influence of ethanol content, pH, and temperature in the water pool.

Investigation of the thermo-reversible properties of different poly( N -isopropyl acrylamide) samples, including microgels and block copolymers, with a combination of methods such as electron microscopy, dynamic light scattering, analytical ultracentrifugation, electrophoresis and ultrasound resonator technology allows comprehensive characterisation of the phase transition. By the combination of methods, it was possible to show that the precipitated polymer phase contains at 40 °C between 40 and 50 vol.% of water. Besides free bulk water, there is also bound water that strongly adheres to the N -isopropyl acrylamide units (about 25 vol.%). Ultrasound resonator technology, which is a non-sizing characterisation method, revealed for the microgel particles two more temperatures (at about 35 and between 40 °C and 50 °C depending on the chemical nature) where characteristic changes in the ultrasound attenuation take place. Moreover, the experimental data suggest that the phase transition temperature is related to surface charge density of the precipitated particles.