Key words: supercritical carbon dioxide, polymers, polyolefins, tetraphenylporphyrin, photocatalytic activity
Low-density polyethylene (LDPE) and polypropylene (PP) films are impregnated with tetraphenylporphyrin (TPP) in supercritical carbon dioxide (SC-CO2) medium to obtain composites active in photocatalytic processes. TPP concentration (evaluated from the intensity of Sore line in electronic absorption spectrum) can reach 3 · 10-9 mol/cm2 in LDPE films. The impregnated polymers possess photocatalytic activity in gas-phase singlet oxygen (1O2) generation; measured 1O2 flows reached 3 · 10-9 mol/s ·cm2. Certain changes in structure and mechanical characteristics in LDPE and PP samples were observed after their treatment in SC-CO2. According to X-ray structure analysis (XSA) data (low-angle scattering), such treatment leads to some disordering in amorphous domains of materials under study, especially in the case of LDPE. In turn, according to wide-angle scattering XSA, crystal structures of both polymers remain unchanged. The conclusions about structural changes in polyolefins caused by treatment in SC-CO2 are confirmed by the results of mechanical testing and thermogravimetric analysis.