Water soluble polymers backbone

Another kind of intelligent polymer molecule in solution is based on the incorporation of the key chemical groups of a know recognition sequence from a natural biomolecule, randomly along a water-soluble polymer backbone, and in the same ratio as in the natural recognition molecule [120]. Under the action of external stimulus the conformational changes of polymer chain can enhance the possibility of recognition. 

Hydrophobically associating water-soluble polymers are of interest because of their unusual properties in solution. Even small levels of hydrophobic groups on water-soluble polymer backbones can have a profound effect on aqueous solution rheology. For example, solutions of such polymers show enhanced viscosification efficiency, shear-thickening rheology, as well as improved shear and salt stability [1-19]. 

The first seven chapters deal with complexes formed by the association of hydrophobic groups on water-soluble polymer backbones. These polymers pose a synthetic problem because of the incompatibility of the two monomer types. Characterization is also challenging, especially for polymers with low hydrophobe content. 

In the case of water-soluble polymers, there is another factor that has to be taken into account when considering solubility, namely the possibility of hydrophobic interactions. If we consider a polymer, even one that is soluble in water, we notice that it is made up of two types of chemical species, the polar functional groups and the non-polar backbone. Typically, polymers have an organic backbone that consists of C—C chains with the majority of valence sites on the carbon atoms occupied by hydrogen atoms. In other words, this kind of polymer partially exhibits the nature of a hydrocarbon, and as such resists dissolution in water. 

PVCL is one of several nonionic water-soluble polymers that undergo heat-induced phase separation in water (Fig. 13). It has a repeating unit consisting of a cyclic amide, where the amide nitrogen is connected directly to the hydrophobic polymer backbone. 

When a water-soluble polymer is dissolved in water, a complex network is formed that includes the polymer backbone, free water, and water in various degrees of bonding to the polymer. Depending on the concentration of polymer, its molecular weight, and several other factors, the network of polymer and bound water can assume the volume of the solution. This, of course, leads to the high viscosity that these solutions develop. The volume occupied by the polymer and the associated water in the system are said to be the hydrodynamic volume. As this volume increases because of increases in molecular weight or in the water shell surrounding the molecule, the viscosity of the solution increases. 

In summary, we described a system in which a backbone containing a highly polar group contains a degree of cross-linking. Put another way, the system is a three-dimensional network of water-soluble polymer and cross-linking that serves as the basis for all hydrogels, natural or synthetic. 

Binding behavior of transition metal ions with polyallylamine20), poly(e-A-methacryloyl-L-lysine)2,), branched poly(ethyleneimine)s 22), water soluble polymer-bound iminodiacetic acid analogue 23), and polyacrylamide gel 241 has been reported. In these works, the effect of the polymer backbone has been discussed in terms of interaction of metal ions with the polymer chains. 

As pointed out by Heller (2), polymer erosion can be controlled by the following three types of mechanisms (1) water-soluble polymers insolubilized by hydrolytically unstable cross-links (2) water-insoluble polymers solubilized by hydrolysis, ionization, or protonation of pendant groups (3) hydrophobic polymers solubilized by backbone cleavage to small water soluble molecules. These mechanisms represent extreme cases the actual erosion may occur by a combination of mechanisms. In addition to poly (lactic acid), poly (glycolic acid), and lactic/glycolic acid copolymers, other commonly used bioerodible/biodegradable polymers include polyorthoesters, polycaprolactone, polyaminoacids, polyanhydrides, and half esters of methyl vinyl ether-maleic anhydride copolymers (3). 

A new process from the paint industry may have application for the suspension coating of pesticide crystals [25]. Low molecular weight water-soluble vinyl polymer chains are synthesized and the process stopped with a terminal vinyl group on each polymer chain. Hydrophobic acrylic monomers are then idded to create the hydrophobic strongly adsorbing backbone polymer. As each water-soluble polymer terminal vinyl group reacts with the growing hydrophobic backbone polymer it becomes inserted like a tooth on a comb. Indeed, these polymer structures are referred to as comb polymers. 

In general terms. Type I erosion encompasses water-soluble polymers that have been insolubilized by hydrolytically unstable crosslinks. Type II erosion includes polymers that are initially water-insoluble and are solubilized by hydrolysis, ionization, or protonation of a pendant group. Type III erosion includes hydrophobic polymers that are converted to small water-soluble molecules by backbone cleavage. 

The temperature sensitivity of the polysaccharides, which is partly a consequence of the ether linkage in the backbone of the polymer (38), has lead to the increasing use of synthetic water-soluble polymers for high temperature drilling fluids. The use of synthetic polymers for fluid loss control in high temperature applications has been particularly im-... 

Novel polymerization techniques were used to synthesize new macro-molecules that consisted of a water-soluble backbone unth small amounts of hydrophobic functionality. Micellar polymerization is based on the capability of surfactant micelles to solubilize hydro-phobic molecules into an aqueous medium it was used to copolymerize acrylamide and hydrophohically substituted acrylamide monomers. A critical aspect of these polymerizations was the incorporation of the hydrophobic monomer into the water-soluble polymers. A method that used the UV chromophore of newly synthesized N-aryl substituted acrylamides was developed to quantify incorporation at the low levels of hydrophobe normally used about 1 mol %). The synthesis of the substituted acrylamides, the UV technique, and results obtained with it are discussed. 

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