Nanoparticle spontaneous formation

Faure, C., Derre, A. and Neri, W. (2003) Spontaneous formation of silver nanoparticles in multilamellar vesicles. Journal of Physical Chemistry B, 107, 4738-4746. 

Sakai T, Alexandridis P (2005) Spontaneous Formation of Gold Nanoparticles in Poly(ethylene oxide)-Poly(propylene oxide) Solutions Solvent Quality and Polymer Structure Effects. Langmuir 21 8019-8025... 

Spontaneous formation of nanoparticles can be achieved by taking advantage of the solubility and gelling properties of a dissolved polymer. Usually, the step allowing polymer colloidal particles to form is reversible, and it is necessary to complete the procedure by a second step required to stabilize the particles. 

Cha JN et al (2003) Spontaneous formation of nanoparticle vesicles from homopolymer polyelectrolytes. J Am Chem Soc 125 8285... 

Besides rings, spontaneous formation of nanoparticle strip patterns has been observed on dewetting a dilute film of polymer coated nanoparticles floating on a water surface [577]. Hybridization of branched DNA trimers and Au nanoparticle DNA conjugates have been employed to produce discrete self-assembled nanoparticle dendrimers [578]. Self-assembly of triangular and hexagonal CdS nanocrystals into complex structures such as rods and arrows has been observed [579]. Furthermore, self-assembly of CdSe nanoparticle-copolymer mixtures has been observed wherein the copolymers assemble into cylindrical domains that dictate the distribution of the nanoparticles [580]. 

Banerjee, R., S. Dutta, S. Pal, and D. Dhara (2013). Spontaneous formation of vesicles by self-assembly of cationic block copolymer in the presence of anionic surfactants and their application in formation of polymer embedded gold nanoparticles. The Journal of Physical Chemistry B 117(13) 3624-3633. 

J. Huang, R Kim, A. R. Tao, S. Connor, and P. Yang, Spontaneous formation of nanoparticle stripe patterns through dewetting. Nature Mat, 4 896-900 (2005). 

A method to self-assemble molecular electronic devices has been developed in our laboratory [8], consisting of stratification, i.e. spontaneous separation of polymer and nanoparticles when spin coating from a common bicomponent solution. The stratification leads to spontaneous formation of polymer layers with different concentrations of nanoparticles. The stratification is realized by mixing both dissolved polymer and the colloid solution, containing nanoparticles to be stratified with two different solvents, each solvent possessing different solubility towards each component and different boiling points. 

The entropic part of the Gibb s free energy in forming intercalates and exfoliates is of critical importance. In the classical treatment of entropy, the entropy of mixing should be positive and contribute to the spontaneous formation of intercalates and exfoliated systems. Countering this increase in entropy is the decrease in entropy experienced by the polymer chain, as it must uncoil in order first, to intercalate and, second, to exfoliate the nanoparticle, yielding the maximum interfacial interaction between the polymer and clay nanoparticles. 

It should be pointed out that the above spontaneous formation of nanogels overcomes the inconveniences of today applied methods for nanoparticle preparation, such as the use of organic solvents and surfactants. The drug carriers based on P-CDs are of a great importance... 

Many reports are available where the cationic surfactant CTAB has been used to prepare gold nanoparticles [127-129]. Giustini et al. [130] have characterized the quaternary w/o micro emulsion of CTAB/n-pentanol/ n-hexane/water. Some salient features of CTAB/co-surfactant/alkane/water system are (1) formation of nearly spherical droplets in the L2 region (a liquid isotropic phase formed by disconnected aqueous domains dispersed in a continuous organic bulk) stabilized by a surfactant/co-surfactant interfacial film. (2) With an increase in water content, L2 is followed up to the water solubilization failure, without any transition to bicontinuous structure, and (3) at low Wo, the droplet radius is smaller than R° (spontaneous radius of curvature of the interfacial film) but when the droplet radius tends to become larger than R° (i.e., increasing Wo), the microemulsion phase separates into a Winsor II system. 

Finally, our group reported on gold nanoparticles decorated with bent-core liquid crystals showing pattern formation on TEM grids after slow solvent evaporation (18 in Fig. 22). These particles showed interesting self-assembly effects in different bent-core liquid crystal hosts (SmCPA and Colr) and slightly improved electro-optic effects such as shorter response time, x, and unaltered spontaneous polarization in the SmCPA host, but no mesophase formation [547]. 

Mesoporous silica containers can be used as inhibitor hosts with controlled release properties triggered at the beginning of the corrosion process in response to local pH changes. For instance, mesoporous silica nanoparticles covered with polyelectrolyte layers can be loaded with an inhibitor (2-(benzothiazol-2-ylsulfanyl)-succinic acid) prior to introduction into a hybrid zirconia-silica sol-gel film. This hierarchical design avoids spontaneous release of the inhibitor by the formation of a polyelectrolyte shell over the container s outermost surface. 

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