Polymeric betaines

Very recently, a new class of water-soluble imide-based polymers known as polymeric betaines has been discovered with a view for application in medicine. Polymers possessing positive and negative charges on the same repeat unit are insoluble in pure water because of the formation of intra- and inter-chain associations. However, they become soluble in water after adding small amounts of salt (e.g., NaCl). Some of these polymeric betaines have attracted much interest for their biocompatible properties due to strong resistance toward protein absorption [64, 65]. 

---

Controlled release formulations, 7 551 pesticide formulations, 7 551-553 Controlled rheology, 14 275 Controlled stress viscometers, 21 736-737 Controlled structure polymeric betaines, 20 481... 

Hamley, I. 2004. Developments in Block Copolymer Science and Technology. Wiley, Hoboken, NJ. Hamley, I. 2006. Block Copolymers in Solution Fundamentals and Applications. Wiley, Hoboken, NJ. Harada, A., Hashidzume, A., and Takashima, Y. 2006. Supramolecular Polymers, Oligomers, Polymeric Betains. Springer, New York. 

Pielichowski, K., Njuguna, J., Janowski, B., and Pielichowski, J. Polyhedral oligomeric silsesquioxanes (POSS)-containing nanohybrid polymers, Adv. Polym. Sci. (2006), 201 (Supramolecular Polymers, Polymeric Betains, Oligomers), 225-296. 

Keywords Application Complexes Polymeric betaines Solutions and gels Zwitterions... 

As the synthesis of polymeric betaines has already been the subject of several reviews [1-5], this chapter is focused on the developments and progress made during the last decade. 

As for any other functional polymer, polymeric betaines are accessible by two different synthetic routes (1) the polymerization of zwitterionic monomers or (2) the zwitterionic functionalization of reactive precursor polymers. Both routes have inherent advantages and disadvantages. The polymerization of the zwitterionic monomers leads to polymers with 100% betaine functionality, but their molecular characterization is difficult for several reasons. For instance, the conformation of the polymers in aqueous solution is very sensitive, not only to the ionic strength but also to the type of added salt, and in the case of polycarbobetaines also to the pH. Furthermore, polymeric zwitterions often exhibit strong interactions with other matter, e.g., chromatographic colmnns. Hence, reliable GPC or HPLC measurements are very difficult to perform, if at all. 

Sulfobetaines are typically prepared by alkylsulfonation of a monomeric or polymeric tertiary amine with strained sultones, usually 1,3-propanesultone or 1,4-butanesultone. An alternative route is the reaction of tertiary amines with a haloalkylsulfonate. Most of the early investigations on polymeric betaines relate to the sulfo derivatives 23a-e, 24, 25, and 26 listed in Scheme 5 [1-4,178]. 

---