Preparation polymer nanoparticles

Figure 14.9 Schematic of the process of preparing polymer nanoparticles and films via a miniemulsion route, (a) First, a solution of the polymer in an organic solvent is mixed with water containing an appropriate surfactant. A miniemulsion is then formed on stirring and ultrasonication. Finally, the solvent is evaporated, resulting in solid polymer nanoparticles dispersed in water.

Pileni and coworkers also used reverse micelles to prepare polymer nanoparticles (169). In the preparation, reverse micelles of dodecyldimethylammo-nium methacrylate in a water-toluene mixture were mixed with the radical initiator AIBN, followed by UV irradiation for 7 h. The polymerization yields were estimated to be 50-70%. The polymer could not be separated from monomers, presumably because of the low molecular weight. The latex particles thus obtained were about 2 nm in diameter. At higher water/surfactant ratios, the size distribution of the particles increased, but the average diameter remained about 2 nm. 

Rao, J. P. Geckeler, K. E. (2011). Polymer nanoparticles Preparation techniques and size-control parameters. Fh ogress in Polymer Science, Vol. 36, 7, (July 2011), pp. (887-913), ISSN 0079-6700... 

Noble metal nanoparticles dispersed in insulating matrices have attracted the interest of many researchers fromboth applied and theoretical points of view [34]. The incorporation of metallic nanoparticles into easily processable polymer matrices offers a pathway for better exploitation of their characteristic optical, electronic and catalytic properties. On the other hand, the host polymers can influence the growth and spatial arrangement of the nanoparticles during the in situ synthesis, which makes them convenient templates for the preparation of nanoparticles of different morphologies. Furthermore, by selecting the polymer with certain favorable properties such as biocompatibiHty [35], conductivity [36] or photoluminescence [37], it is possible to obtain the nanocomposite materials for various technological purposes. 

Chemical reduction of metal salts in solution is the most widely used method of preparation of metal nanoparticles, especially in laboratories. In general, the reducing reagents are added into the solution of the precursor ions, but in some cases, a solvent works as a reductant. Various reducing reagents have been proposed to prepare metal nanoparticles. Ethanol or small alcohols can reduce precious metal ions such as Au, Pt", Pd, Ag, and so on [3j. Polymer-stabilized precious metal nanoparticles and their alloy particles can be used as good catalysts for various reactions. Polyols, such as ethylene glycol, were... 

Preparation of nanoparticles can be by a variety of different ways. The most important and frequently used is emulsion polymerization others include interfacial polymerization, solvent evaporation, and desolvation of natural proteins. The materials used to prepare nanoparticles are also numerous, but most commonly they are polymers such as poly-alklcyanoacrylate, polymethylmethacrylate, poly-butylcyanoacrylate, or are albumin or gelatin. Distribution patterns of the particles in the body can vary depending on their size, composition, and surface charge [83-85]. In particular, nanoparticles of polycyanoacrylate have been found to accumulate in certain tumors [86,87]. 

Akagi T, Baba M, Akashi M (2007) Preparation of nanoparticles by the self-organization of polymers consisting of hydrophobic and hydrophilic segments potential applications. Polymer 48 6729-6747... 

It is not possible to determine the molecular weight of highly cross-linked polymers and natural polymers by GPC as they do not dissolve in tetrahydrafuran. Accurate results for molecular weight can only be obtained if the polymer standards used have similar properties to the polymer employed to prepare the nanoparticles. In most cases, this similarity is absent. 

Microemulsions are used as reaction media for a variety of chemical reactions. The aqueous droplets of water-in-oil micro emulsions can be regarded as minireactors for the preparation of nanoparticles of metals and metal salts and particles of the same size as the starting microemulsion droplets can be obtained [1-3]. Polymerisation in micro emulsions is an efficient way to prepare nanolatexes and also to make polymers of very high molecular weight. Both discontinuous and bicontinuous micro emulsions have been used for the purpose [4]. Microemulsions are also of interest as media for enzymatic reactions. Much work has been done with lipase-catalysed reactions and water-in-oil microemulsions have been found suitable for ester synthesis and hydrolysis, as well as for transesterification [5,6]. 

Table 1. Methods for the preparation of nanoparticles based on polymers used candidate drug and...

Hydrophilic nanoparticle carriers have important potential applications for the administration of therapeutic molecules [28,53]. Most of the recently developed hydrophobic-hydrophilic carriers require the use of organic solvents for their preparation and have a limited protein-loading capacity [54,55]. Calvo et al. [56] reported a new approach for the preparation of nanoparticles, made solely of hydrophilic polymer, to address these limitations. The preparation technique, based on an ionic gelation process, is extremely mild and involves the mixing of two aqueous phases at room temperature. 

Synthetic Polymers Physical Properties and Methods of Preparation of Nanoparticles... 

Nanoparticles of PS (M =1.0xl0 -3.0xl0 mol ) microlatexes (10-30 nm) have also been successfully prepared from their respective commercial PS for the first time [75]. The dilute PS solutions (cyclohexane, toluene/methanol or cyclohexane/toluene) were induced to form polymer particles at their respective theta temperatures. The cationic CTAB was used to stabihze th microlatexes. The characteristics of these as-formed PS latex particles were quite similar to those obtained from the microemulsion polymerization of styrene as reported in literature. These microlatexes could also be grown to about 50 nm by seeding the polymerization of styrene with a monodisperse size distribution of D /Djj=1.08. This new physical method for preparing polymer nano-sized latexes from commercial polymers may have some potential applications, and therefore warrants further study. 

Some non-oxide nanoparticles such as PbS and CdS can be used to prepare polymer-inorganic nanocomposites by a double-microemulsion process [103]. In this case, two precursor micro emulsions must be prepared separately first and then mixed together for polymerization. Using CdS-polymer nanocom-... 

Polymer nanoparticles including nanospheres and nanocapsules (Fig. 1) can be prepared according to numerous methods that have been developed over the last 30 years. The development of these methods occurred in several steps. Historically, the first nanoparticles proposed as carriers for therapeutic applications were made of gelatin and cross-linked albumin. Then, to avoid the use of proteins that may stimulate the immune system and to limit the toxicity of the cross-linking agents, nanoparticles made from synthetic polymers were developed. At first, the nanoparticles were made by emulsion polymerization of acrylamide and by dispersion polymerization of methylmethacry-late.f These nanoparticles were proposed as adjuvants for vaccines. However, since they were made of non-biodegradable polymers, these nanoparticles were rapidly substituted by particles made of biodegradable... 

Poly(V-vinylpyrrolidone) (PVP) was used in two methods for preparing polymer nanoflbers containing Ag nanoparticles [62]. The first method involved electro-spiniung the PVP nanoflbers containing Ag nanoparticles directly from the PVP solutions containing the Ag nanoparticles. DMF was used as a solvent for the PVP as well as a reducing agent for the Ag ions in the PVP solutions. In the second method, PVA aqueous solutions were electrospun with 5 wt% of the PVP... 

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