Study on the solution properties of ZnO QDs-embedded MEO2MA m –HEMA n –MEO2MA m triblock copolymers

Abstract

Two ABA triblock copolymers (A = 2-(2-methoxyethoxy) ethyl methacrylate, MEO2MA; B = 2-hydroxyethyl methacrylate, HEMA) MEO2MA200–HEMA50–MEO2MA200 and MEO2MA200–HEMA30–MEO2MA200 have been prepared by atom transfer radical polymerization (ATRP). The copolymers were characterized by FTIR, 1H NMR spectroscopy and Viscotek TDAmax GPC/SEC. Their thermoresponsive behaviors in aqueous solution were monitored with turbidity, phase diagram, steady fluorescence and rheological property. The absorbency of copolymer solutions at varied temperatures was recorded to determine the lower critical solution temperature (LCST) of copolymer solutions. The LCSTs were found to decrease a few degrees as the concentration and hydrophobic HEMA moiety increased. The critical gelation concentration and five regions of copolymer solutions were determined by the phase diagrams. MEO2MA200–HEMA50–MEO2MA200 was shown to have a lower critical gelation concentration than MEO2MA200–HEMA30–MEO2MA200. The rheological properties of copolymer solutions were recorded to study the gelation capacity of copolymer solutions. It revealed that the moduli of MEO2MA200–HEMA50–MEO2MA200 were higher than those of MEO2MA200–HEMA30–MEO2MA200 above the gelation temperature. To investigate the micellization behaviors of the polymers, the steady fluorescence spectroscopy using pyrene as the probe was recorded. The results indicated that the critical micelle concentration of MEO2MA200–HEMA50–MEO2MA200 solution was lower than that of MEO2MA200–HEMA30–MEO2MA200. Low cytotoxic poly(2-(dimethylamino)ethylmethacrylate) (PDMAEMA)-co-PMAA-capped ZnO quantum dots labeled triblock copolymer solutions and free standing gels emitted yellow emission under UV light. Embedding quantum dots into copolymer solutions did not vary the gelation capacity in spite of slight influence on G′ and G″ moduli. With further biocompatibility testing, the ZnO QDs-labeled triblock copolymers could potentially be applied as thermoresponsive, biolabeling and injectable biomaterials for functional embolization.