Graft polymers isolation

Ccdculated from sulfur anadysis of grafted polymer isolated after removal of starch by acid hydrolysis. 

To a suspension of polystyrene-graft-chloroformate (0.5 g, 0.41 mmol based on loading of 0.81mmol/g) dissolved in 6 ml THF was added 4-methoxypyridine (0.48 mmol) and methylmagnesium chloride (0.81 mmol) dissolved in 3 ml. Thereafter, additional THF was added, the mixture immediately filtered, and the modified graft polymer isolated. FTIR data supplied. 

The product from Step 1 was washed successively with a mixture of 3 M HCl and THF, 1 1, 3M HCl, methyl alcohol, N,N-dimethyl-formamide and diethyl ether, dried, and the modified graft polymer isolated. FTIR data supplied. 

Expanding the variety and properties of linker groups increases the scope of practical applications of radiation-grafted polymer surfaces for the parallel synthesis of organic compounds. Linker molecules have a bearing on the types of reactions that can be performed and the ease of isolation of products after cleavage. 

The effect reported in 7,88) was attributed to the higher hydrophilicity of the graft copolymers as compared to the cellulose esters. The authors did not allow for the role played by the grafted polymer structure in these reactions. At the same time, it could be interesting to investigate the conversion of cyano groups in the graft copolymer and in PAN chains isolated from the copolymer so that their supramolecular and molecular structures would remain intact. 

Fig. 3 Cartoon representation of an isolated grafted colloidal sphere (black core) along with the calculated monomer density profile 0(r) (for various core radii, re) [119]. The three solid lines correspond to values of the ratio of the overall particle radius R to the grafted polymer end-to-end distance of 0.5, 2 and 16, from bottom to top, respectively. The dashed line represents the self-consistent field theory calculation for the flat brush limit (r [119]. Note the depletion region...

We can also assess the state of knowledge on block polymers in 1962. Ceresa (33). in his book "Block and Graft Copolymers" included the syntheses of 1400 block copolymers. He pointed out that less than 5% of the block and graft polymers described had been isolated with a reasonable purity and that fewer than 20 species had been analyzed and characterized fully. He attributed this situation to the fact that linear or graft block polymers are contaminated with homopolymers. In many cases the block polymer was present as only a small percentage of the final mixture. 

The advent of controlled radical polymerization methods, such as ATRP, RAFT, and NMP, has allowed for a wide variety of new block and graft polymers to be prepared due to the chemical variety of monomers which can be polymerized by these methods (Matyjaszewski and Tsarevsky, 2009 Matyjaszewski and Braunecker, 2007). Block copolymers can be polymerized by sequential monomer addition, but more often the first block is synthesized, isolated, and... 

Figure 6.10. Possible structures of grafted polymer layers in poor solvents, showing isolated collapsed coils (mushrooms) laterally phase-separated clusters or bundles and a homogeneous collapsed layer. After Tang and Szleifer (1994).

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