Nanostructures polymer brushes

Padeste C, Farquet P, Potzner C, Solak HFI. Nanostructured bio-functional polymer brushes. J Biomater Sci Polym Ed 2006 17(11) 1285—300. 

Scanning electron microscopy (SEM) is one of the very useful microscopic methods for the morphological and structural analysis of materials. Larena et al. classified nanopolymers into three groups (1) self-assembled nanostructures (lamellar, lamellar-within-spherical, lamellar-within-cylinder, lamellar-within-lamellar, cylinder within-lamellar, spherical-within-lamellar, and colloidal particles with block copolymers), (2) non-self-assembled nanostructures (dendrimers, hyperbranched polymers, polymer brushes, nanofibers, nanotubes, nanoparticles, nanospheres, nanocapsules, porous materials, and nano-objects), and (3) number of nanoscale dimensions [uD 1 nD (thin films), 2 nD (nanofibers, nanotubes, nanostructures on polymeric surfaces), and 3 nD (nanospheres, nanocapsules, dendrimers, hyperbranched polymers, self-assembled structures, porous materials, nano-objects)] [153]. Most of the polymer blends are immiscible, thermodynamically incompatible, and exhibit multiphase structures depending on the composition and viscosity ratio. They have two types of phase morphology sea-island structure (one phase are dispersed in the matrix in the form of isolated droplets, rods, or platelets) and co-continuous structure (usually formed in dual blends). 

In direct write lithography, a tip can be used to pattern a surface and prepare polymeric nanostructures. Polymerization is initiated by the tip and a pattern is formed. Polymer brush nanostructures can be synthesized using ring opening metathesis polymerization (ROMP). Edge distances of less than 100 nm are possible, and control over feature size, shape, and interfeature distance is achievable. 

Most work on REMP was done with COE (8) or cyclooctadiene (COD) (9) but functionalized monomers can also be used. A dendronized macro-monomer 10 (Figure 1.4) has been used under REMP conditions, leading to the formation of cyclic nanostructures with a diameter of 35-40 nm [40]. Recently, a REMP-derived cyclic macro-initiator derived from monomer 11 was used to prepare cyclic brush copolymers by combining REMP with triazabicyclodecene-catalyzed ring-opening polymerization of a cyclic ester [41]. Furthermore, REMP processes were developed for the synthesis of functional cyclic polymers, cyclic polymer brushes, and cyclic gels [42, 43]. 

POE 13] PoELMA J.E., Fors B.P., Meyers G.F. et al, Fabrication of complex three-dimensional polymer brush nanostructures through light-mediated living radical polymerization , Angewandte Chemie International Edition, vol. 52, pp. 6844-6848, 2013. 

Orski, S. V., Fries, K. H., Sontag, S. K., Lockhn, J. (2011). Fabrication of nanostructures using polymer brushes. Journal of Materials Chemistry, 21,14135-14149. 

Wang et al. [31] used a surface-initiated reverse atom transfer radical polymerization (reverse ATRP) technique to synthesize the well-controlled nanostructure of polymer brushes from silicon wafer. PMMA brushes were prepared by modifying the surface of the silicon substrate with peroxide... 

In a non-electrochemical method with N4 type complexes, Kimura et al. [50] detected volatile organic compounds using a Quartz Crystal Microbalance coated with SAM s of nanostructured macromolecular metal complexes of Co-Pc, Ni-Pc, Cu-Pc or Zn-Pc in the form of polymer brushes. The method was based on the highly hydrophilic character of the brushes and on their good performance as anion exchangers... 

Motornov M, Sheparovych R, Katz E, Minko S. Chemical gating with nanostructured responsive polymer brushes mixed brush versus homopolymer brush. ACS Nano... 

Cylindrical Polymer Brushes Synthesis and Application as Templates for Organic-Inorganic Nanostructures... 

The molecular organization of biopolymers is often much more complex than that of polymers synthesized in a chemical laboratory. Work is underway to systematically close this gap. Recent progress in controlled radical polymerization has made it possible to synthesize increasingly complex ionic macromolecules with controlled dimensions and topology. As a result, well-defined ionic block copolymers [10], colloidal [4] and molecular [8] PE brushes, and star-like PEs [9] have become available. In addition to emerging applications, such nanostructures constitute excellent model systems. 

After all our efforts, membrane research is still challenging and in need of fresh and innovative ideas. It is a highly interdisciphnary field, based on molecular chemistry, polymer physics, interfacial science and the science of random heterogeneous media. Could it be possible that the future lies in ordered nanostructured materials such as, for example, ordered polyelectrolyte brushes In such materials, studying the role of the sidechains (length, separation, controlled flexibility, hydrophobicity) and mechanisms of self-assembly, which will determine proton distribution at the mesoscopic scale, will be central for design and optimization. 

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