Capping, poly

The most commonly used polymers are cellulose acetate phthalate [9004-38-0] (CAP), poly(vinyl acetate phthalate) [34481-48-6] (PVAP), hydroxypropylmethyl-ceUulosephthalate [71138-97-1] (HPMCP), and polymethacrylates (111) (see Cellulose esters). Acrylate copolymers are also available (112). Eigure 11 shows the dissolution behavior of some commercially available enteric materials. Some manufacturers supply grades designed to dissolve at specific pH values with increments as small as 0.5 pH unit (113). 

Ethylene oxide capped poly(oxypropylene) diol, MW 2800 100... 

Noell et al. reported the preparation of silica-poly(ether ether ketone) hybrid materials with improved physical properties.155 An amine-end-capped poly(ether ether ketone) was used to react with isocyanatopropyltriethoxysilane in tetrahydrofuran (THF). The triethylsilane-end-capped poly (ether ether ketone) was mixed with tetraethoxysilane (TEOS) in THF. Quantitative amounts of water were introduced into die system, and the mixture was reduxed at 80°C. The entire reaction mixture was allowed to further react in Tedon molds. Tough transparent materials were obtained by diis approach. 

The rate of hydrolysis of the partially ethoxylated polymer was retarded, although not to the extent calculated from theory (Fig. 25), suggesting some contribution to the rate of chain scission by an uncatalyzed process. End-capping poly (glycolic acid-co-lactic acid) has a similar effect on the rate of hydrolysis of this polyester (100). 

Michel, Y. M., Poncet, D., Piron, M., Kean, K. M., and Borman, A. M. (2000). Cap-poly (A) synergy in mammalian cell-free extracts. Investigation of the requirements for poly (A)-mediated stimulation of translation initiation. J. Biol. Chem. 275, 32268-32276. 

Preparation of Krebs-2 translation extracts Krebs-2 extracts are an ideal system to screen for compounds that inhibit translation because they faithfully recapitulate the cap dependency and the cap-poly(A) synergism associated with eukaryotic mRNA translation (Svitkin and Sonenberg, 2004), unlike standard rabbit reticulocyte lysates (RRL) (Borman et al., 2000). Furthermore, the translation of many types of IRESes is supported in Krebs-2 extracts. The use of commercially available translation competent extracts prepared from RRL, wheat germ, and E. coli is extremely useful in assessing selectivity of inhibitors identified in primary screens. 

Although the biocompatibility and biodegradability of these materials were rapidly determined, the bioactivity of Si02-PCL hybrid materials was not studied until recently [99]. In order to provide bioactivity to Si02-PCL hybrid materials, Rhee prepared triethoxysilane end-capped poly(s-caprolactone) which was then cocondensed with tetraethyl orthosilicate and calcium nitrate via the sol-gel method. The Ca-containing PCL/silica hybrid so obtained showed in vitro bioactivity and biodegradability. The hybridization procedure between the a,co-hydroxyl PCL and silica phases was proposed to be as follows ... 

Fig. 10. Amide end-capped poly(hexafluoropropy-lene oxide) used for the inverse emulsion polymerization of acrylamide in C02 [123]...

This basic approach to chemical amplification was subsequently extended by Ito et al. [3] through resist formulations incorporating appropriately chosen triaryl sulfonium or diaryliodonium salt. For example, end-capped poly(phthalaldehyde) used in combination with an onium salt photoacid generator is an excellent self-... 

Figure 7.16 (A) Dendron-capped poly(triacetylene) and, (B) soluble oligothiophenes obtained by dendrimers assisted synthesis...

Goh HW, Goh SH, Xu GQ, Lee KY, Yang GY, Lee YW, Zhang WD (2003). Optical limiting properties of double-C60-end-capped poly(ethylene oxide), double-C -end-capped polyethylene oxide)/poly(ethylene oxide) blend, and double-C -end-capped poly(ethylene oxide)/multiwalled carbon nanotube composite. J. Phys. Chem. B 107 6056-6062. 

Hybrid materials have been made by incorporating end-capped poly(tetramethylene oxide) blocks to tetramethoxysilane sol-gel glasses. These materials have high extensibility with interdispersed organic and inorganic regions. 

Peng S, An Y, Chen C, Fei B, Zhuang Y, Dong L (2003) Thermal degradation kinetics of uncapped and end-capped poly(propylene carbonate). Polym Degrad Stab 80 141-147... 

Figure 7.8 Chemical structures of 2,6-bis(l methylbenzimidazolyl) pyridine (Mebip) end-capped poly(2,5-dioctyloxy-p-phenylene ethynylene) (PPE) (5) and poly(2,5-dioctyloxy-p-xylylene) (PPX 6) MSPs and pictures of the resulting fibers and films (Knapton, Iyer, et al. 2006 Knapton, Rowan, et al. 2006).

Uchida N, Hoshino S, Imataka H, Sonenberg N, Katada T (2002) A novel role of the mammalian GSPT/eRE3 associating with poly(A)-binding protein in Cap/Poly(A)-dependent translation. J Biol... 

Triethoxysilane-capped poly(arylene ether ketone), PEK, or poly(arylene ether sulfone), PSF... 

Preparation of N-Capped poly-a-L-glutamic acid General procedure... 

H. Cheradame, J. Habimana de la Croix, E. Rousset, and F.J. Chen, Synthesis of polymers containing pseudohalide groups by cationic polymerization. 9. Azido end-capped poly(2-methylpropene) by polymerization initiated by the system lewis acid-2-azido-2-phenylpropane, Macromolecules, 27(3) 631-637, January 1994. 

Here we report the results of using a series of hydroxyl-capped poly(ethylene glycols), PEGs. These PEG can be considered to be of the form below. 

Fig. 16 TEM pictures showing nanoparticles of cholesteryl end-capped poly(NIPA-co-dimethylacrylamide). The nanoparticles were obtained by the dialyzing dimethylfor-mamide solutions of copolymers against water and subsequent freeze-drying. The initial concentrations of the copolymer in dimethylformamide were a-c 0.35 wt%, d 0.1 wt%, e, f 1.2 wt%. a, c-f were obtained for the copolymer with Mw = 3400 b was obtained for the copolymer with Mw = 8000. (Reprinted with permission from Ref. [55]. Copyright 2003 Elsevier)...

Table VII. Solvents for Acetate End-Capped Poly-n -Butyraldehyde...

Preparation of Coumarin Ester End-Capped Poly(E-Caprolactone-co-Trimethylene Carbonate)... 

M Poly(s-Caprolactone-co-Trimethylene Carbonate) (daltons) OH value (mol/g) M of Post UV Cured End-Capped Poly(E-Caprolactone-co-Trimethylene Carbonate) Coumarin Ester (daltons)... 

The specific inclusion of adamantyl groups in /3-cyclodextrin in aqueous environments has been used as binding interaction between adamantyl end-capped poly(ethylene oxide)263-264 or polyester and a cyclodextrin polymer. Even though the formation of linear chain extended structures was not specifically... 

Flydroxyl-capped poly (ethylene-co-butylene), a so-called Kraton, was converted into a macroinitiator via esterification with 2-bromopropionyl chloride, and then employed for the block copolymerizations of styrene and />acetoxystyrene (B-116 and B-117).403 A similar method is utilized for B-l 18 to B-121 where the esterification is with 2-bromoisobutyroyl bromide.341 A commercially available polybutadiene is also employed for B-122 via a similar transformation into the chloroacetyl group.404... 

In a study, copper-catalyzed radical copolymerization of nBA and methacryloxy-capped poly(MMA) was compared with conventional radical copolymerization.267 431 The graft copolymers G-l obtained with copper catalysts are more homogeneous in terms of MWD (Mw/Mn 1.6 vs 3) and the number of side chains. This is attributed to diffusion control being less important in the metal-catalyzed radical polymerization, where the growing radical species is rapidly converted into the dormant covalent species. 

There are several examples of graft copolymers obtained from macromonomer prepared by the metal-catalyzed polymerizations. Conventional radical copolymerization of TV-vinylpyrrolidione and vinyl acetate-capped polystyrene synthesized with copper catalysts gave graft copolymers G-2, which formed hydrogels in water.337 Electrochemical copolymerization of pyrrole and thiophene-capped poly(MMA) affords G-3.335... 

Monomethoxy-capped poly(ethylene glycol) M = 1100,20.0 g, 18.3 mmol... 

Add monomethoxy-capped poly(ethyleneglycol) (M = 1100,20.0 g, 18.3 mmol) to a clean, dry three-necked flask (500 ml) under a positive pressure of dry... 

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