Polystyrene capsules

The best results were obtained by using the block copolymer surfactant SE3030 together with the nonionic initiator PEGA200 which supports interface stabilization and improves the structural perfection (Fig. 18a) of the polystyrene capsule morphology. 

Hollow and porous polymer capsules of micrometer size have been fabricated by using emulsion polymerization or through interfacial polymerization strategies [79,83-84, 88-90], Micron-size, hollow cross-linked polymer capsules were prepared by suspension polymerization of emulsion droplets with polystyrene dissolved in an aqueous solution of poly(vinyl alcohol) [88], while latex capsules with a multihollow structure were processed by seeded emulsion polymerization [89], Ceramic hollow capsules have also been prepared by emulsion/phase-separation procedures [14,91-96] For example, hollow silica capsules with diameters of 1-100 micrometers were obtained by interfacial reactions conducted in oil/water emulsions [91],... 

In this technique, an rf encodable microchip is coupled with a capsule of derivatized polystyrene resin such that each unique synthesis site can be tagged with a unique identifier code. The inert nature of the rf transponder construction renders this tagging strategy compatible with virtually all synthetic methods. Additionally, the noninvasive transmission or retrieval of information from any capsule is unambiguous and instantaneous, avoiding the possibility of long reaction and/or analysis times associated with chemical tags. 

An excellent example where a capsid virus has been given a new supramolecular application can be found in the work of Nolte who took an icosahedral capsid virus, cowpea chloritic mottle virus (CCMV) and used it as a nanoreactor for polymer synthesis [30], Natural CCMV spontaneously assembles in acidic aqueous solution and disassembles in basic solution. The capsid contains pores open at pH 5 to release RNA into the host. Once the RNA leaves, the empty capsule is left. The Nolte group was able to assemble the subunits around polystyrene sulfonate with a mass of 9.9 kDa but the resulting structure had a different morphology to the natural system. Indeed, capsules formed around polymers with masses between 2 and 85 kDa but not around those with masses above 100 kDa. This raised the question of the potential for polymers to form within a capsid but to test the possibility a mixture of botanical, biological and chemical approaches was needed. 

The samples are placed, usually immediately after being collected, in different types of containers made of plastic, aluminium or other metals, glass, etc., depending on their future use and the storage temperatures. In this preliminary phase the BCAA decided to use polycarbonate containers for soils, sediments, moss and algae polystyrene containers for filters collecting marine suspended particulate matter polystyrene Petri capsule for filters with atmospheric particulate matter low-density polyethylene (LDPE) containers for snows and polyethylene bags for pack-ice core. 

Choosing a block-copolymer with both hydrophilic and hydrophobic domains as the amphiphilic substance, the appHcation of suitable linking methods can lead to the formation of an irreversibly closed capsule around every single nanotube. The reaction with a diamine linker may for instance initiate a crosslinking in the polyacryhc acid domains of an amphiphilic polystyrene/polyacrylic acid copolymer. Upon addition of water to a solution in DMF the latter form micelles with the nanotubes in the center. Contrary to the simple micelles mentioned in the previous paragraph, the crossHnked species can be dried and redispersed. 

In a totally segmented CPFR of the stratified agitated tower design, the feed stream is considered to enter the reactor as macro-molecular capsules which maintain their integrity throughout their life-time inside the reactor. The capsules each act as though they were batch reactors and theoretically should produce a monodisperse polystyrene having a Poisson distribution. 

The latter also affects the structure of polystyrene occlusions, i.e., instead of the usually formed cellular rubber particles, the "tangle" particles and the particles of "capsule" type are formed (Figure 4). Analogous changes of particle types were observed by Ekhte when investigating the structure of a homopolystyrene mixture with block copolymers of different block size (9). 

The comparison of different types of nanoparticles embedded in capsule shells in the terms of interaction with laser light was performed in paper. The main goal was to establish the difference between pre-synthesized silver nanoparticles and the ones fabricated by "silver mirror" reaction during the shell formation process. One type of the capsules was built using calcium carbonate cores of 11.5 m in diameter, and the other one was fabricated on the surface of 10.25 pm polystyrene microspheres. Pre-fabricated nanoparticles were adsorbed from the mixture of silver sol and anionic polyelectrolyte (PSS) solution in 0.5M NaCl. 

At the same time it was possible to destroy the capsules with nanoparticles adsorbed from sol with the 830 nm IR laser, because those nanoparticles had high enough absorbance at this wavelength. Moreover, the capsules formed on calcium carbonate cores were destroyed at lesser laser beam power values than the ones formed on polystyrene cores. This fact can be explained by the difference in adsorption pattern of silver nanoparticles. Nanoparticles adsorbed on the polystyrene cores formed an uniform layer while those adsorbed on the calcium carbonate cores formed "clusters". 

Also, it was established that minimal power needed to de-struct the capsules depended not only on the core type but also on the adsorbed metal mass. Power needed for the capsules destruction comes down similary for the capsules produced on different cores when the mass of the adsorbed silver changes from 3.2 10 to 9.6 10 gramms per capsule. At the same time the sensitivity to the laser radiation for the capsules produced on polystyrene cores is much higher than the one for the capsules produced on CaCOs cores. 

Probably it is connected with the difference in polyelectrolyte shells structure and capsules size. More drastic increase in the sensitivity to a laser beam at the further increase of adsorbed nanoparticles quantity was observed for capsules formed on CaCOs rather than for the ones formed on polystyrene cores. Apparently, the agglomeration of nanoparticles occurs at this quantity of nanoparticles. 

Selected Examples. - Qiao et al investigated diffusion exchange of dextran with molecular weights 4.4 and 77 kDa through polyelectrolyte multilayer (PEM) hollow capsules consisting of four bilayers of polystyrene... 

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