International audienceAn approach to the synthesis of new regular graft-copolymers polyimide (PI)-graft-polymethacrylic acid is elaborated, including (1) synthesis of multicenter PI macroinitiators, (2) controlled ATRP of tert-butylmethacrylate on the prepared macroinitiators, and (3) protonolysis of tert-butyl ester groups of side chains of the resulting PI-graft-poly(tert-butylmethacrylate). Experimental conditions for attaining complete conversions of the first and the third stages of the process are determined by means of 1H NMR and FTIR-spectroscopy. Polymer products of the first and the second stages of the process, as well as poly(tert-butylmethacrylate) side chains cleaved from the PI-graft-poly(tert-butylmethacrylate) copolymers by complete decomposition of the PI backbone under alkaline hydrolysis conditions, are characterized by GPC. The kinetics of poly(tert-butylmethacrylate) chain growth on a PI macroinitiator under ATRP conditions are studied. The results obtained provide evidence for the controlled character of the ATRP process and the regular structure of the synthesized graft-copolymers. It is shown that PI-g-PMAA PI brushes are significantly more efficient intracellular delivery agents for the potential photosensitizer [tetra(4-fluorophenyl)tetracyanoporhyrazine free base] than are the commonly used PEG-micelles

Thermal rearrangement of polyimides with OH side groups results in insoluble products (TR polymers) that reveal extremely high gas permeability combined with good permselectivity. However, the mechanism of the formation of these polymers remains unclear, as well as there are some doubts about their chemical structure. In order to elucidate this problem, infrared (IR) spectra of TR polymers were recorded and compared with those of several polyimide precursors. IR spectra in the range 400−4000 cm −1 showed numerous bands that evidenced the formation of aromatic lactam structure in the final products of thermal rearrangement, while only weak bands indicated the presence of benzoxazole structure. It was also shown that thermal rearrangement of functionalized polyimides studied leads to highly permeable TR polymers: permeability coefficients (P) increased by a factor of 5−20, compared to those of the polyimide precursors.

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