Acta Polymerica 40 (1989) Nr. 4 260 BLOSS, HERQETH et al.: Association of polyoxyeth y lene-polyoxypropylene block copolymers FLORY-HUGGINS parameter is a linear function of @ , for t h e range of 0.35 5 @ , 5 0.65: This result is in contrast t o investigations reported in t h e literature [7, 121, where t h e concentration dependence of x on @ , is neglected in all cases; b u t t h e values themselves are close t o t h e %-values presented above. ConclusionsT h e method presented permits t h e determination of t h e equilibrium distribution of liquid substances with a low molar mass in polymer dispersions using ultrasonic velocity data. T h e distribution coefficient can b e determined with a n accuracy of &0.5y0. This method is applicable t o all types of additives, polymers a n d dispersion media since no system is known which contains ingredients which all have t h e same ultrasonic velocities or elastic constants.T h e monomer concentration at t h e reaction locus a n d t h e diameters of t h e monomer swollen latex particles as well as the FLORY-HUGGINS parameter are determinable by this method. These quantities are of significant importance for t h e control of polymerization processes.Disadvantages of this method lie in t h e existence of a minimum polymer concentration of 5% i n dispersion media, which is nessesary t o detect t h e polymer by ultrasonic techniques, a n d in t h e inapplicability t o gaseous monomers under normal pressure (e.g. vinyl chloride, butadienej.Polymer Sci. 26 (1981) 1351.The water-solubility of triblock copolymers of poly(oxyethy1ene) and poly(oxypropy1ene) is caused by the binding of water to the oxygen of the OE units. Two water molecules are bound to one OE unit as can be derived from measurements of ultrasound velocity and density of the solutions. This binding is lost by increasing the temperature, and, therefore, the polymer precipitates from aqueous solution. The existence of polymeric associates can be detected by investigations of the viscosity as well as by static and dynamic light scattering. Assoziate yon Poly(oxyethyZen)-PoZy(oxypropylen)-Blockcopolymeren in wapriger L6sungDie Wasserloslichkeit von Triblockcopolymeren des Poly(oxyethy1ens) und Poly(oxypropy1ens) wird verursacht durch die Bindung des Wassers an den Sauerstoff der Oxyethylen-Einheiten. Aus Schallgeschwindigkeits-und Dichtemessungen an den Losungen kann abgeleitet werden, daS im Mittel zwei Wassermolekule je OE-Einheit gebunden sind. Temperaturerhohung fuhrt zum Aufbrechen dieser Bindung und damit zum Ausfallen des Polymers aus der Losung. Die Entstehung von Polymerassoziaten wird mit Viskositatsuntersuchungen sowie statischer und dynamischer Lichtstreuung nachgewiesen. Accoyuamu eonoJcmepoe noJcuoKCwmUnena c noJcuomunponuenoa 8 soanoa pacmsope PaCTBOpHMOCTL Tpm6JIOYHbIX COlTOJIHMepOB IIOJIHOKCH3THJIeHa C IIOJIHOKCIIIIpOII~JIeHOM B Bone BbI3BaHa CBH3bI-BaHHeM MOJIeKyJI BOAbI H a aTOMaX KHCJIOpOAa OKCM3THJIeHHbIX t?AHHHq. 113 H3MePeHHfi CKOPOCTEl3ByKa H IIJIOTHOCTH CJIeAyeT, YTO B CpeAHeM ABe MOJIeKyJ...