Poly dimethylacrylamide

R Arshady, E Atherton, DL Clive, RC Sheppard. Peptide synthesis. Part 1. Preparation and use of polar supports based on poly(dimethylacrylamide). J Chem Soc Perkin 1, 529, 1981. 

To make further use of the azo-initiator, tethered diblock copolymers were prepared using reversible addition fragmentation transfer (RAFT) polymerization. Baum and co-workers [51] were able to make PS diblock copolymer brushes with either PMMA or poly(dimethylacrylamide) (PDMA) from a surface immobihzed azo-initiator in the presence of 2-phenylprop-2-yl dithiobenzoate as a chain transfer agent (Scheme 3). The properties of the diblock copolymer brushes produced can be seen in Table 1. The addition of a free initiator, 2,2 -azobisisobutyronitrile (AIBN), was required in order to obtain a controlled polymerization and resulted in the formation of free polymer chains in solution. 

Fig. 6 Transmission electron micrograph (TEM) of the cross-section of a PDMAAm(poly-dimethylacrylamide)-b-PST(polystyrene) block-graft-copolymerized surface stained in iodine vapor, a Spurr s resin, b PST layer, c PDMAm layer, d dithiocarbamate (DC)-derivatized PST film...

Fig. 20 Phosphorylcholine-containing iniferter derivatized on glass through silane coupling agent (upper) and graft chain photopolymerized with poly(dimethylacrylamide) (lower)...

Epinephrine adrenaline or 4-[l-hydroxy-2-(methylamino)ethyl]-l,2-ben-zenediol hydrochloride EPDMA epoxy poly(dimethylacrylamide) ... 

In 1971, Sheppard proposed that peptide synthesis would proceed more efficiently if the polymeric support was designed to have solvation properties similar to those of the peptide product.This line of reasoning led to the development of polyamide resins.The most successful of this type of support is based on cross-linked poly(dimethylacrylamide) (Pep-syn). Polyamide resins swell up to 10 times their dry volume in dimethylformamide and even more in water. On the other hand, they swell much less in dichloromethane. The few comparative studies that have been carried out between polystyrene and polyamide resins indicate that both give very similar results in routine solid-phase peptide synthesis. 

The poly(dimethylacrylamide) resin was functionalized with an internal reference norleucine residue and with the acid-labile 4-alkoxybenzyl alcohol linkage agent. Esterification of the C-terminal Fmoc-Gly residue was performed using the pentafluorophenyl ester (5 equiv) with DMAP as catalyst (1 equiv) and was complete in 1-2 hours. All peptide bond-forming reactions used Fmoc amino acid ODhbt ester (4 equiv) in DMF but a later synthesis using only 2 equiv except for the final valine (4 equiv) also gave satisfactory results. The completed decapeptide was cleaved from the resin with 95% TFA and purified by HPLC. 

Current practice of the conventional solid phase peptide synthesis (the Merrifield method) is based largely on the use of polystyrene and poly-dimethylacrylamide supports (see Fig. 17). The latter polymer was introduced in the 1970s [12,133 to provide a relatively more polar support, as compared with polystyrene. However, accumulation of experimental evidoice since then (ct Rrf. 70), indicates that an ideal polyn r support for SPPS should be comi tible with both polar (H-bonding) and nonpolar (hydrophobic) residues on the peptic grafts (Fig. 17). When the polymer support is not compatible with the growing peptide grafts, phase separation occurs, and the synthesis becomes inefficient or impracticable. 

Chen, L., Ren, J., Bi, R., and Chen, D., Ultraviolet sealing and poly(dimethylacrylamide) modification for poly(dimethylsiloxane)/glass microchips. Electrophoresis, 25 (2004) 914—921. 

Finally, the styrene-divinylbenzene copolymer is certainly not the only starting material suitable for functionalization. Impermeable polymers were grafted and porous glass beads coated with organic polymers for derivatization, but these pioneering efforts had few followers so far. More auspicious seems to be, at this time, the application of polyamides, such as polyacrylamide, poly-dimethylacrylamide or polydimethylacrylamide-co-Boc-j -alanylacroyl-hexa-methylenediamine. Their promise stems from the compatibiUty of the support with the peptide chain. 

Isomerization from cis to trans and back of azo groups, however, is not the only mechanism that can affect photo-viscosity change in polymeric solutions. Thus, reversible solution viscosity changes were also observed [222] in solutions of poly(dimethylacrylamide) with pendant triphenylmethane leucohydroxide in methanol. This can be illustrated as follows ... 

Figure 3. Deprotection peak heights as a function of host residue (-X-X-) and chain length in the SPPS of the known difficult peptide test sequence H- Ala) -X-X-(Ala)3-Val-poly-dimethylacrYlamide (I). (a) General hydrophobic residues, (b) Eff of side-chain protection of cysteine, (c) Effect of trityl protection of side-chain carboxamide of glutamine and asparagine, (d) Effect of arginine and tertiary amino acids proline and sarcosine. (Reproduced from ref. 51 with permission from Munksgaard International Publishers Ltd., Copenhagen.)...

Lin, W.C., Fan, W., MarceUan, A., Homdet, D., Cretan, C., 2010. Large strain and fractare properties of poly(dimethylacrylamide)/sihca hybrid hydrogels. Macromolecules 43,... 

Ayres, N., Haddleton, D.M., Shooter, A.J., and Pears, D.A. 2002. Synthesis of hydrophilic polar supports based on poly(dimethylacrylamide) via copper-mediated radical polymerization from a cross-linked polystyrene surface Potential resins for oligopeptide solid-phase synthesis. Macromolecules 35 3849-55. 

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