Guang-Zhao Li - Synthesis, pH- and temperature-induced micellization and gelation of doubly hydrophilic triblock copolymer of poly(N,N-dimethylamino-2-ethylmethacrylate)-b-poly(ethylene glycol)-b-poly(N,N-dimethylamino-2-ethylmethacrylate) in aqueous s...

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  Publication Details (including relevant citation   information):

  Journal of Polymer Science Part A: Polymer Chemistry


    Volume 46, Issue 17, pages 5869–5878  


  A doubly hydrophilic triblock copolymer of   poly(N,N-dimethylamino-2-ethyl   methacrylate)-b-Poly(ethylene   glycol)-b-poly(N,N-dimethylamino-2-ethylmethacrylate)   (PDMAEMA-b-PEG-b-PDMAEMA) with well-defined   structure and narrow molecular weight distribution   (Mw/Mn = 1.21) was   synthesized in aqueous medium via atom transfer radical   polymerization (ATRP) of   N,N-dimethylamino-2-ethylmethacrylate (DMAEMA)   initiated by the PEG macroinitiator. The macroinitiator and   triblock copolymer were characterized with 1H NMR and   gel permeation chromatography (GPC). Fluorescence spectroscopy,   dynamic light scattering (DSL), transmittance measurement, and   rheological characterization were applied to investigate pH- and   temperature-induced micellization in the dilute solution of 1   mg/mL when pH > 13 and gelation in the concentrated solution   of 25 wt % at pH = 14 and temperatures beyond 80 °C. The unimer   of Rh = 3.7 ± 0.8 nm coexisted with micelle   of Rh = 45.6 ± 6.5 nm at pH 14. Phase   separation occurred in dilute aqueous solution of the triblock   copolymer of 1 mg/mL at about 50 °C. Large aggregates with   Rh = 300–450 nm were formed after phase   separation, which became even larger as Rh =   750–1000 nm with increasing temperature. The gelation temperature   determined by rheology measurement was about 80 °C at pH 14 for   the 25 wt % aqueous solution of the triblock copolymer. © 2008   Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46:   5869–5878, 2008

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