Poly copolymer template

Oligomerization of 2-MeImpG and 2-MeImpA by means of poly(C,U) random copolymer templates produced a variety of oligo(G,A)s.[160]... 

Gold nanoparticles coated by short thiol end functional polystyrene homopolymers (PS-SH) can be incorporated into a poly(styrene-fo-2-vinylpyridine) diblock copolymer template (PS-NP2VP). It has been found that the surface density of PS chains on the gold particles is critical in controlling their location in block copolymer templates [95]. 

Apparent advantage of the prefabricated nanoparticles hes in the opportunity to use well-developed procedures to control particle size and particle size distribution and to characterize the particles by all possible means. Prefabricated particles can be introduced in the mesoporous materials in two ways. One avenue is direct incorporation of particles in sol-gel mixture as was recently reported in [60]. Here mesostructured nanoparticle-sihca monoliths have been synthesized by dispersing prefabricated Au or zeohte (sihcate) nanoparticles in sol-gel precursors containing SiCl4 and a Pluronic triblock copolymer template. To improve the compatibility of the Au nanoparticles with the poly(ethylene oxide) block, the nanoparticle surface was modified with a SiOj layer. Therefore, this technique requires good compatibihty of nanoparticles with the components of the sol-gel reaction, as it influences the distribution of nanoparticles through the material. Another hmitation of this method is encapsulation of particles within mesoporous material, but not necessary location in the pores. As was discussed above, this limitation is especially crucial for catalytic applications. 

B. W. Boudouris, C. D. Frisbie, M. A. Hillmyer, Nanoporous Poly(3-Alkylthiophene) Thin Films Generated from Block Copolymer Templates. Macromolecules 2008,41,67-75. 

Boudouris, B.W., Frisbie, C.D., and Hilhnyer, M.A. (2008) Nanoporous poly(3-alkylthiophene) thin films generated from block copolymer templates. Macromolecules, 41,67—75. 

Polymerization of 4-vinylpyridine onto alternating styrene-maleic anhydride copolymer leads to similar results. Very low molecular weight (500) was found for poly(vinylpyridine) obtained onto template with molecular weight 4640. The authors explain the results in terms of the unfavorable location of the monomer units on the copolymer template. 

Among the many different dopants studied, tin oxide doped with antimony (Sn02 Sb, also known as ATO) is worth mentioning as it is also used as a transparent semiconductor oxide. Wang et al. [78] synthesized ATO powders by reacting SnCl and 15 mol% Sb(OC2Hs)3 in 2 ml of ethanol in the presence of 36wt% poly(ethylene-co-butylene)-f>/oc/ -poly(ethylene oxide) copolymer template. The sol was left to dry at room temperature and finally calcined at 500 °C. 

Ti-SBA-15 Grafting method. SBA-15 prepared first using the amphiphilic triblock copolymer poly(ethyleneox-ide) -poly (propyleneoxide) -poly (ethyleneoxide) (EO-PO-EO) as template and TEOS as Si source. The composition was 2 g copolymer 0.021 mol TEOS 0.12 mol HC1 3.33 mol H20. The solid was calcined at 600 K for 4 h to remove the copolymer. Ti in the form of titanium isopropoxide was grafted onto the dehydrated surface of SBA-15 Pore diameter = 6.3 nm, surface area = 518 m2/g, pore volume = 0.68 (25)... 

Deviations are also observed in some copolymerizations where the copolymer formed is poorly soluble in the reaction medium [Pichot and Pham, 1979 Pichot et al., 1979 Suggate, 1978, 1979]. Under these conditions, altered copolymer compositions are observed if one of the monomers is preferentially adsorbed by the copolymer. Thus for methyl methacrylate (M1 )-/V-vinylcarbazole (M2) copolymerization, r — 1.80, r2 = 0.06 in benzene but r — 0.57, > 2 0.75 in methanol [Ledwith et al., 1979]. The propagating copolymer chains are completely soluble in benzene but are microheterogeneous in methanol. /V-vinylcarba-zole (NVC) is preferentially adsorbed by the copolymer compared to methyl methacrylate. The comonomer composition in the domain of the propagating radical sites (trapped in the precipitating copolymer) is richer in NVC than the comonomer feed composition in the bulk solution. NVC enters the copolymer to a greater extent than expected on the basis of feed composition. Similar results occur in template copolymerization (Sec. 3-10d-2), where two monomers undergo copolymerization in the presence of a polymer. Thus, acrylic acid-2-hydroxyethylmethacrylate copolymerization in the presence of poly(V-vinylpyrrolidone) results in increased incorporation of acrylic acid [Rainaldi et al., 2000]. 

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