Copolymers with short grafts

These can be made by copolymerizing two monomers, one of which contains a side-chain such as Cio or C12, e.g. the copolymerization of norbomene dicarboxylic esters with 5-decylnorbom-2-ene. Alternatively, the homopolymer of the diester can first be hydrolyzed to the acid form and then partially reacted with 1-dodecylamine. The viscosity of aqueous solutions of such hydrophobically modified polymers increases sharply with increase in concentration as a result of intermolecular association (McArdle 1995). 

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The structure of a multi block copolymer does not seem suitable for the purpose. On the other hand, the structure of graft copolymers with short polysiloxane branches is considered to be the exact structure for the purpose, since one may maintain film forming properties, flexibility of slloxane chain (high permeation rate), and high selectivity. The flexibility of the slloxane chain can be maintained in side chains of graft copolymers and film forming properties and selectivity of permeation can be provided by backbone For this purpose, polystyrene was chosen as the backbone material... 

A new class of amphiphilic, surface-active graft copolymers, hydrophobically modified hydroxyethyl celluloses (HM-HEC s), are comprised of a cellulose backbone with short polyethylene oxide (PEO) and grafted alkyl side chains. They are excellent steric stabilizers of 0/W emulsions. 

It should be mentioned 104> that the aziridinyl methacrylate can be copolymerized first with a comonomer, and subsequently the dangling aziridinyl moieties are reacted with short polymer chains bearing terminal carboxy groups. Both procedures yield the same graft copolymers. 

The same authors132) studied the copolymerization of short co-methacryloyl-PMMA macromonomers with monomers such as styrene, vinyl acetate and acrylonitrile using AIBN as the initiator. They found that the copolymers formed are free of homopolymer these graft copolymers possessing a small number of very short grafts exhibit properties similar to those of the backbone chains. 

Cellulose esters and cellulose ethers are prepared based on the substitution of cellulose hydroxyl groups with short chain regents. Cellulose can also be modified by introduction of long chain polymer(s) onto its main chain. The products are mostly grafted copolymers, and in some cases, block copolymers can also be made. 

Linear polypeptide block copolymers, block copolymers with pendent sugar or peptide grafts, and modified linear or dendritic homopolymers have been used to produce vesicles based on hydrophobic interactions and packing issues. Usually, the peptides or sugars make the minority hydrophilic part of the copolymers and are thus incorporated in the corona and not in the membrane of the vesicles. For the inverse case, the hydrophobic peptides in the membrane are often too short to adopt a stable secondary structure. 

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