Block polymers anionic ring

Summary PDMS-6-PEO short-chain diblock copolymers were prepared via anionic ring-opening polymerization of cyclosiloxanes. Applying this method, various well-defined block copolymers with different compositions were synthesized and their phase behavior was investigated. The polymers predominantly showed lamellar phases in aqueous solutions. At small surfactant concentrations, vesicles were formed, as observed via cryogenic TEM. The aggregates of the diblock copolymers were used for the formation of lamellar thin films, applying the evaporation-induced self-assembly approach. 

Although polysiloxanes have superior properties compared to common organic polymers, the controlled formation of amphiphilic block copolymers consisting of a pure polysiloxane backbone remains essentially unexplored. There have been only a few reports of such polymers in the literature, for example one bearing pendant carboxyl groups on the polysiloxane chain,and another prepared by a one-pot sequential anionic ring-opening polymerization of two cyclotrisiloxanes. ... 

Homopolymers, as well as random and block copolymers with PDMS, were created by a combination of polycondensation and anionic ring-opening polymerization. To convert the chlor-opropyl side groups into quaternary ammoniums, the polymer was first treated with lithium bromide to replace the chlorine with bromine. The polymer was dissolved with (3-hydroxypro-pyl)dimethylamine to create the amphiphilic quaternary amine-functionalized polymer. Bactericidal assays of statistical and block copolymers gave MIC values of 6-25 pgmr against E. coli and S. aureus, with somewhat better activity against S. aureus. 

Fig. 2.14 Scheme illustrating the synthesis of ABC type tri-block polymer with hydrophilic PEO middle block using AROP. 1 Anionic polymerization followed by hydrogenation, 2 Anionic ring-opening polymerization, and 3 Chain end functionalization followed by atom transfer radical polymerization... 

Luisier A, Bourban P E and Manson J A E (2002) Initiation mechanisms of anionic ring-opening polymerization of lactam-12, J Polym Sci Polym Chem Ed 40 3406-3415. Yamashita Y, Matsui H and Ito K (1972) Block copolymerization V. Block anionic polymerization of lactams, J Polym Sci Polym Chem Ed 10 3577-3587. 

Keul, H. and Hoecker, H. (1988) Anionic ring-opening polymerization of carbonates and formation of block copolymers. Integration of Fundamental Polymer Science-2 Proceedings, International Meeting on Polymer Science and Technology, Rolduc. 

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