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Double stimuli-sensitive ABA block copolymers
|Christo B. Tsvetanov , Philip A. Dimitrov , Erol A. Hasan|
Institute of Polymers, BAS (IP BAS), Acad G.Bonchev St. 103A, Sofia BG-1113, Bulgaria
Thermoassociative block copolymers usually consist of a water-soluble segment and a temperature-responsive one. In this study novel thermally sensitive ABA blockcopolymers were obtained carrying a central polypropylene oxide block (PPO) with molecular weight of 2000 D and outer blocks of poly(N-isopropylacrylamide) (PNIPAAm) or poly(ethoxyethylglycidyl ether) (PEEGE). Ceric ion redox method and ATRP were applied for the synthesis of PNIPAAm-b-PPO-b-PNIPAAM by using PPO as a precursor. The PEEGE-b-PPO-b-PEEGE blockcopolymers were prepared by sequential anionic polymerization using Cs alkoxides as initiators. Hence the resulting copolymers were comprised of blocks with different lower critical solution temperatures in aqueous media, which allowed us to obtain thermoassociative blockcopolymers characterized by two-step phase transition. This attractive behaviour will allow the development of nano-particles or micro-aggregates with two different cores. Such advancement could potentially provide the groundwork for a unique drug delivery system capable of carrying two biologically active compounds with different drug release profiles.
Presentation: invited oral at E-MRS Fall Meeting 2004, Symposium B, by Christo B. Tsvetanov
See On-line Journal of E-MRS Fall Meeting 2004
Submitted: 2004-04-29 15:22 Revised: 2009-06-08 12:55