ON THE MOLECULAR MECHANISM OF CLOUDING IN AQUEOUS-SOLUTION OF POLY(OXYETHYLENE)-POLY(OXYPROPYLENE)-POLY(OXYETHYLENE) TRIBLOCK COPOLYMERS

The physical aspects of the clouding phenomenon in the aqueous solution of a poly(oxyethylene) (POE) - poly(oxypropylene)(POP) - poly(oxyethylene)(POE) triblock copolymer were investigated by applying various experimental methods: viscometry, ultrasonic technique, light scattering, infrared and Raman spectroscopy. The ultrasonic absorption studies hint at a critical behaviour. In order to understand the spectroscopic findings, conformational energies of model POE molecules as well as interaction energies between oxyethylene (OE) units and water molecules were calculated by the use of the quantum chemical PCILO method. It is suggested that the clouding is connected with conformational changes of POE segments.