Association and surface properties of diblock and triblock copoly(oxyethylene/oxypropylene/oxyethylene)s

Abstract

M 13 9PL , UK Oxyethylene/oxypropylene block copolymers were prepared with almost identical overall compositions (40 wt.% E) and molecular weights (M, = 2900) but different block structures, i.e. diblock E2,P2, and triblock E,4P30E,4. Their micellar and surface properties were studied by static and dynamic light scattering and surface tension. At a given temperature, the surface acitivity, the c.m.c., the molar micellar weight and the micellar size did not differ within the uncertainties of their determination. The only significant difference was in the area per molecule in the surface monolayer, wherein the diblock copolymer was more closely packed than the triblock copolymer.

Effect of Cosolvents and Cosolutes upon Aggregation Transitions in Aqueous Solutions of the Poloxamer F87 (Poloxamer P237): A High Sensitivity Differential Scanning Calorimetry Study

“…Several studies have recognized that the aggregation process is fairly complex in that several aggregation states have been noted. − , Preceding micelle formation light scattering has detected the formation of extremely large aggregates whose generation has been attributed to the presence of a relatively hydrophobic diblock impurity. ,, These aggregates break up on warming, and the diblock impurity is thought to become incorporated into the micelles.…”

“…For example poloxamer P407 (F127) (chemical formula EO 108 PO 69 EO 108 ), used as obtained from the manufacturer, gels at concentrations greater than 170 g kg -1 − Micellization has been studied using a wide variety of techniques. In previous contributions to the literature we have explored the use of NMR and more importantly high-sensitivity differential scanning calorimetry (HSDSC) to characterize these phenomena. − More recently, we have successfully fitted the observed HSDSC signals to a mass action based aggregation model …”

Effects and measurements of polyoxyethylene block length in polyoxyethylene‐polyoxybutylene copolymers

“…DSC was used to determine the relative average EO block length for POB/POE block copolymers. Linear equations for each of these variables are as follows: 7h = (--524/E0#) + 67 [4] Hf = (--543/E0#) + 178 [5] where 7)n = peak melting temperature in ~ Hf --heat of fusion in J/g, and EO# --the average number of EO monomer units in the POE diol. During the heating process step, a glass transition for the POB block occurs near -65 ~ At a higher temperature, an endothermic melting transition occurs, and the associated heat of fusion can be calculated.…”

“…In particular, polyalkylene oxide block copolymers made from propylene oxide (PO), 1,2-butylene oxide (BO) and ethylene oxide (EO) comprise a major class of nonionic surfactants presently in use (1)(2)(3)(4)(5). In particular, polyalkylene oxide block copolymers made from propylene oxide (PO), 1,2-butylene oxide (BO) and ethylene oxide (EO) comprise a major class of nonionic surfactants presently in use (1)(2)(3)(4)(5).…”

Effect of Surfactants on Association Characteristics of Di- and Triblock Copolymers of Oxyethylene and Oxybutylene in Aqueous Solutions: Dilute Solution Phase Diagrams, SANS, and Viscosity Measurements at Different Temperatures

“…For example, B block is more hydrophobic than P block and EB or EBE copolymers are fairly homogeneous in composition [1]. The surfactantlike properties including gelation behavior of several of laboratory synthesized or commercial E n B n and E n B m E n copolymers in aqueous media have been the subject of many scientific investigations [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. In colloidal engineeringbased applications such as detergency, dispersion, stabilization, foaming, emulsification, lubrication, control release of drugs, the block copolymers and low molar mass surfac-tants are often used in combination with each other.…”