Core-shell polymer nanoparticles

Y. Qu, J. Liu, K. Yang, Z. Liang, L. Zhang and Y. Zhang, Boronic Acid functionalized core-shell polymer nanoparticles prepared by distillation precipitation polymerization for glycopeptide enrichment, Chem-Eur J., 2012,18(29), 9056-9062. 

The synthesis of core-shell magnetic nanoparticles from polyacrylic acid (PAA) graft copolymers containing side chains of PEO and PPO (Fig. 5) was demonstrated by Hatton et al. [102]. Using a mixture of the polymers at a temperature of 180°C, amine-terminated PEO and PPO were coupled onto the PAA via amidation. Super-paramagnetic polymer-coated nanoparticles were synthesized by the hydrolysis and condensation of Fe(II) and Fe(III) chloride salts in the presence of PPO- or PEO-modified PAA copolymers. The extraction of organic compounds from aqueous media towards the copolymer shell of hydrophobic PPO segments can be applied in the field of water purification. 

Zhang J. L., Srivastava R. S, and. Misra R D. K (2007). Core-Shell Magnetite Nanoparticles Surface Encapsulated with Smart Stimuli-Responsive Polymer Synthesis, Characterization, and LCST of Viable Drug-Targeting Delivery System, Langmuir, Volume 23, Issue 11, pp 6342-6351. 

Norakankom C, Pan Q, Rempel GL et al (2010) Factorial experimental design on synthesis of functional core/shell polymeric nanoparticles via differential microemulsion polymerization. J Appl Polym Sci 116 1291-1298... 

Rao et al. [82] incorporated doxorubicin into PNBE by a hydrazine linker (Figure 7.8a) and obtained core-shell polymeric nanoparticles soluble in water and biological media. The drug was easily released by hydrolysis of the hydrazine linker at lower acidic conditions of pH = 5.5-6 as compared to the pH = 3.0 in the case of doxorubicin connected to the polymer by an amide linkage. 

Yuan-Qing L, Shao-Yun F, Yang Y, Yiu-Wing M (2008) Facile synthesis of highly transparent polymer nanocomposites by introduction of core-shell structured nanoparticles. Chem Mater... 

Thermosensitive, and amphiphilic polymer bmshes optically active polymers consist of helical poly(iV-propargylamide) main chains and thermosensitive poly(iV-iso-propylacrylamide) (PNlPAm) side chains, were prepared via a novel methodology combining catalytic polymerization, atom transfer radical polymerization (ATRP), and click chemistry. The characterization of GPC, FT-IR, and H-NMR measurements indicated the successful synthesis of the novel amphiphilic polymer brashes. For the confirmation of helical structure of the polymers backbones and the optical activity of the final brashes used UV-Vis and CD spectra. The polymer with optically active cores (helical polyacetylenes) and thermosensitive shells (PNlPAm) brashes self-assembled in aqueous solution forming core/shell structured nanoparticles [137]. 

Optically active polymers show another properties namely thermosensitivity, e.g., main chains helical poly(iV-isopropylacrylamide) and thermosensitive part as side chain of poly(A -isopropylacrylamide) (PNlPAm). Such type of polymers synthetic method described elsewhere [137]. The polymer with optically active cores (helical polyacetylenes) and thermosensitive shells (PNlPAm) brashes self-assembled core/shell structured nanoparticles in aqueous solution. Another example of optically active polymer is poly[/V-(L)-(l-hydroxymethyl)-pro-pylmethacrylamide] (P(l-HMPMA)) of lower critical solution temperature and thermosensitivity. Circular dichroism and microcalorimetric measurements of the polymer showed the polymer chains in a state of relatively low hydration compared to that of by racemate synthesized monomers by free-radical reaction formed P(d,l-HMPMA). Thermosensitivity and structural effects were obtained by microscopic observation of aqueous solution of polymers and its hydrogels [138]. 

Rothon and Hancock (1995) observed that it is widely assumed that fillers are cheap and that polymers are expensive. Conversely, for nanoparticles it is widely assumed that nanoparticles are expensive and that polymers are cheap. This is not necessarily the case. As the nanoparticle manufacturing industry expands, nanoparticles are increasingly available in large (i.e., tonne) quantities. The prices of expensive nanoparticles such as carbon nanotubes are also being reduced. The price of nanoparticles varies greatly with the type, as well as with the purity of the material. For example, silica nanoparticles supplied dispersed as a masterbatch in epoxy cost about 20/kg (Nanoresins 2008), and core-shell rubber nanoparticles similarly dispersed cost approximately 12/kg (Kaneka 2008). Nanoclays can cost as little as 7/kg (SigmaAldrich 2008). However, a kilogram of carbon nanotubes cost between 400 and 98,000 in Autumn 2009 (CheapTubes 2009). 

FIGURE 14.3 Possible morphologies of magnetie latex partieles (a) core-shell, (b) nanoparticles dispersed in a polymer matrix, and (c) nanoparticles immobilized onto seed particles. 

Hyperbranched polymer falls in the category of core-shell organic nanoparticles. Hyperbranched polymers are considered as mutant offspring of... 

Another method to synthesize hollow nanocapsules involves the use of nanoparticle templates as the core, growing a shell around them, then subsequently removing the core by dissolution [30-32]. Although this approach is reminiscent of the sacrificial core method, the nanoparticles are first trapped and aligned in membrane pores by vacuum filtration rather than coated while in aqueous solution. The nanoparticles are employed as templates for polymer nucleation and growth Polymerization of a conducting polymer around the nanoparticles results in polymer-coated particles and, following dissolution of the core particles, hollow polymer nanocapsules are obtained. 

Fig. 30 Types of nanocarriers for drug delivery, (a) Polymeric nanoparticles polymeric nanoparticles in which drugs are conjugated to or encapsulated in polymers, (b) Polymeric micelles amphiphilic block copolymers that form nanosized core-shell structures in aqueous solution. The hydrophobic core region serves as a reservoir for hydrophobic drugs, whereas hydrophilic shell region stabilizes the hydrophobic core and renders the polymer water-soluble.

A scaled-up version of this central template-concentric sphere surface assembly approach has been demonstrated for the growth of multi-layer core-shell nano- and microparticles, based upon the repeated layer-by-layer deposition of linear polymers and silica nanoparticles onto a colloidal particle template (Figure 6.8) [60]. In this case, the regioselective chemistry occurs via electrostatic interactions, as opposed to the covalent bond formation of most of the examples in this chapter. The central colloidal seed particle dictates the final particle... 

Allard E, Larpent C (2008) Core-shell type dually fluorescent polymer nanoparticles for ratiometric pH-Sensing. J Polym Sci Part A Polym Chem 46 6206-6213... 

Cammas, S., Suzuki, K., Sone, Y, Sakurai, Y., Kataoka, K., and Okano, T. Thermo-responsive polymer nanoparticles with a core-shell micelle structure as site-specific drug carriers. J. Contr. Rel, 1997,48, 157-164. 

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