Polymer Material for the Construction of the Membrane with the Various Pore Sizes (a Critical Comparison of Various Synthesis Mechanisms)
The goal of this work was to prepare diblock-copolymer which rapidly changes its solubility in the dependency of the temperature. Appropriate diblock-copolymer should consist of one active (hydrophilic) component, and hydrophobic matrix block. The active component should have the switching temperature as close as possible to the human body temperature. Diblock-copolymer should exhibit sufficient mechanical stability, and the polydispersity index should be as low as possible. The mechanically stable components of the diblock copolymer were, polystyrene (PS) or poly(tert-butylmethacrylate) (PtBMA), while as an active component, poly-(2-(2ethoxy)-ethoxy)methoxy methatcrylate (PDEGMA) was used. A polymer required for this purpose should have molar mass of at least 150000 g/mol (in order to posses mechanical stability), and molar ratio of PDEGMA of 0.20–0.40 (in order to get desired structure of hexagonally packed cylinders of PDEGMA in the matrix). The syntheses were performed via different polymerization mechanisms (sequential anionic polymerization, group transfer polymerization, atomic transfer radical polymerization, combination of anionic and atomic transfer radical polymerization. The highest molar masses (Mn>20000 g/mol), lowest polydispersities (Mw/Mn<1.1), and molar amounts of DEGMA exceeding 10% were gained by sequential anionic polymerization. Group transfer polymerization was performed successfully for molar masses up to 22000 g/mol, but no phase separation has been achieved. A PtBMA-PDEGMA random copolymer was achieved employing tetrabutylamoniumbibenzoate (TBABB) as a catalyst, and copolymerization parameters were determined. Atomic transfer radical polymerization has resulted in polymers with molar masses up to 16000 g/mol, and higher polydispersity index compared to the analogous polymers synthesized via sequential anionic polymerization. A combination of anionic and atomic transfer radical polymerization, yielded in copolymers of molar masses up to 25000 g-mol with higher amounts of DEGMA (up to 80 mol%), but with the significant amount (over 20%) of the residual polystyrene macroinitiator.
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