Associative polymers

J. Bock and co-workers, "Hydrophobically Associating Polymers," ia G. A. Stahl and D. N. Schul2, eds., Water-Soluble Polymers for Petroleum Recorey, Plenum Press, New York, 1988, pp. 147—160. 

E. F. Vainstein, A. A. Sokolovskii, and A. S. Kuzminskii, Kinetics of the Changing Products Molecular-Mass Distribution in Thermodegradation of Associated Polymers, Polymer Yearbook, (R. A. Pethrick and G. E. Zaikov, eds.) Gordon and Breach, London, vol. 9, pp. 79-101 (1993). 

Denoting by c the total concentration of the polymers in whatever form and by x the concentration of the non-associated polymers one finds the relation... 

Model Deyelopment. Rachow and Timm (] ) derived working relationships for the kinetic mechanism described. Degree of polymerization is considered to be a continuous variable. For quenched samples a relationship correlating population density of associated polymer molecules as a function of time, degree of polymerization and environmental factors is... 

Ascher and Nemny 495) found that residues of triphenyltin acetate on glass, resulting from the evaporation of acetone solutions thereof, were, on contact to houseflies, less toxic with rising concentration. As triphenyltin acetate is likely to be a self-associated polymer in the solid state [similar to trimethyltin acetate (355)] and in concentrated solutions, it was suggested 495) that the monomer, which exists in dilute solutions, is toxic to insects, and the polymer, nontoxic. Interestingly, in this connection, a triphenyltin methacrylate copolymer has 470) a very low mammalian toxicity (acute, oral LDso for mice >2000 mg/kg). 

Anionic Association Polymer. Another type of lost circulation agent is a combination of an organic phosphate ester and an aluminum compound, for example, aluminum isopropoxide. The action of this system as a fluid loss agent seems to be that the alkyl phosphate ester becomes crosslinked by the aluminum compound to form an anionic association polymer, which serves as the gelling agent [1488]. 

The hybrid techniques often associate polymers and metals and combine the benefits of the two material classes. The metal provides the rigidity and the overmoulded reinforced plastic keeps the shape of the metal and adds numerous functionalities. 

The most important deficiency in the models developed so far concerns the failure to take account of interactions between the mobile ions. As the ionic concentration in polymer electrolytes is frequently greater than 1.0moldm and the mean distance between ions of the order of 0.5-0.7 nm, then relatively stong coulombic interactions exist which must affect ion motion. Ratner and Nitzan have begun to address this problem from a theoretical viewpoint (Ratner and Nitzan, 1989) although it has not been fully developed yet to give a complete description of conduction in ion associated polymer electrolytes. The interactions between ions which lead to ion association are discussed further in the following section. 

Jongschaap RJJ, Wientjes RHW, Duits MHG, MeUema J. A generalized transient network model for associative polymer networks. Mactomolecules 2001 34 1031-1038. 

Loveless DM, Jeon SL, Craig SL. Rational control of viscoelastic properties in multicomponent associative polymer networks. Macromolecules 2005 38 10171-10177. 

Self-Associative Polymer Network. In self-associative polymer networks (often called one component systems), the hydrogen bonding recognition units that are covalently attached to the polymer backbone have an appreciable tendency for self-association, that is, self-dimerize, which leads to interchain cross-linking of the polymers. As a result, the system is inherently cross-linked and does not require any external cross-linking agents for network formation (Fig. 5.11a). Because the cross-linking is based on dimerization phenomena, to achieve effective... 

Figure 5.11 The three distinct classes of hydrogen bonded polymer networks (a) self-associative polymer network, (h) polymer network synthesized via the use of complementary linker molecules, and (c) complementary polymer hlends.

Figure 5.13 Self-associative polymer network formed via the dimerization of 2-ureido-4[lH]-pyrimidone groups attached to the polymer backbone.

The effect of tetrahydrofuran on the polymerization of isoprene in hexane has been studied by Morton and co-workers (73, 74). The viscosity method was used to measure the degree of association. This was found to drop from 2 in pure hexane to about 1.3 with a ratio of THF to polyisoprenyllithium of 100 and dissociation of the polymer aggregates was complete at ratios of 500—700. With the reasonable assumption that the only species present in significant amounts were associated polymer molecules and etherates, it was possible to find the concentration of etherate present under all conditions. An equilibrium constant could be evaluated from the overall process... 

Viscosity of dissolved polymers drops irreversibly under acoustic treatment65 A8). The depolymerization process us rather fast during the first minutes of the treatment and then it becomes slow and ceases completely when the equilibrium molecular mass (MM) M is reached. The higher the polymer s initial molecular mass N0, the higher the rate of destruction. The majority of authors associate polymer destruction in solution with cavitation effects occurring under acoustic treatment. 

Yekta, A., B. Xu, J. Duhamel, H. Adiwidjaja, and M. A. Wnnik. 1995. Fluorescence studies of associating polymers in water determination of the chain end aggregation number and a model for the association processMacromoleculeS8 956-966. 

Trimethyltin hydroxide and isothiocyanate, which are also self-associated polymers in the solid state, (58, 59) show rather smaller... 

Some works were reported in which thermosensitive polymers were conjugated with hydrophobic groups. End-capping random poly(NIPA-co-dimethylacrylamide) [55] and grafting poly(NIPA-co-hydroxymethylacryl-amide) [56] with cholesterol moieties led to self-associating polymers with different morphologies. By dissolution of the copolymers in dimethylfor-... 

The conversion of dextran with 1,2-epoxy-3-phenoxypropane, epoxyoctane or epoxydodecane may be exploited for the preparation of amphiphilic dextran derivatives. Polymeric surfactants prepared by hydrophobic modification of polysaccharides have been widely studied, starting with the pioneering work of Landoll [261]. Neutral water-soluble polymeric surfactants can be obtained by reaction of dextran with 1,2-epoxy-3-phenoxypropane in 1 M aqueous NaOH at ambient temperature (Fig. 35, [229,233]). The number n of hydrophobic groups per 100 Glcp units varies between 7 and 22 depending on the reaction conditions. 2-Hydroxy-3-phenoxy propyl dextran ethers (DexP) behave like classical associative polymers in aqueous solution. In dilute solution, the intrinsic viscosity decreases significantly whereas... 

As association polymers, the caseins can form aggregates in solution with a wide range of sizes, so it is difficult to idendfy any particular size as the units of bioassembly or dissociation of casein micelles. 

---