Synthesis and self-assembly behavior of organic-inorganic poly(ethylene oxide)-block-poly(MA POSS)-block-poly(N-isopropylacrylamide) triblock copolymers

摘要

In this work, the synthesis of 3-methacryloxypropylheptaphenyl POSS, a new POSS macromer (denoted MA-POSS) is reported. The POSS macromer is used to synthesize PEO-b-P(MA-POSS)-b-PNIPAAm triblock copolymers via sequential atom transfer radical polymerization (ATRP). The organic-inorganic, amphiphilic and thermoresponsive ABC triblock copolymers are characterized by means of nuclear magnetic resonance spectroscopy (NMR) and gel permeation chromatography (GPC). Differential scanning calorimetry (DSC) and atomic force microscopy (AFM) show that the hybrid ABC triblock copolymers are microphase-separated in bulk. Cloud point measurements show that the effect of the hydrophiphilic block (i.e. PEO) on the LCSTs is more pronounced than the hydrophobic block (i.e. P(MA-POSS)). Both transmission electron microscopy (TEM) and dynamic light scattering (DLS) show that all the triblock copolymers can be self-organized into micellar aggregates in aqueous solutions. The sizes of the micellar aggregates can be modulated by changing the temperature. The temperature-tunable self-assembly behavior is interpreted using a combination of the highly hydrophobicity of P(MA-POSS), the water-solubility of PEO and the thermoresponsive property of PNIPAAm in the triblock copolymers.