Two Gel States of a PEO-PPO-PEO Triblock Copolymer Formed by Different Mechanisms

Phase behavior of a PEO-PPO-PEO triblock copolymer in aqueous solutions: Two gelation mechanisms

“…For copolymer concentrations ranging from 12 to 32 wt%, soft gels are also observed around the hard gel II boundary in the temperature region from about 40 to 70 o C. The cloud zone is believed to the coexistence state of a hard gel I and a turbid soft gel due to the phase mixing. 18 We also note that aqueous solutions of the Pluronic P103 show turbidity change depending only on the temperature not on the polymer concentration. As presented in Figure 1(b), the temperature range of an aqueous solution can be classified into four distinct regions.…”

“…Moreover recently, we reported that the hard gel II state could not be detected during cooling scan regardless of concentration. 18 This implies that the second gel phase driven by the macroscopic liquid-liquid phase separation is not easily rehydrated upon cooling and not thermoreversible. We believe that the large aggregates consisting of loosely bound micelles transform into more compact structure upon heating since the PEO endblocks become more hydrophobic and partially dehydrated resulting in the phase mixing with PPO and at the same time, the hydrophobic attraction between the PPO cores is even more reinforced.…”

“…18 We proposed different gelation mechanisms of the two gel states formed by a Pluronic P103 (EO 17 PO 60 EO 17 ) containing longer PO block, which is comparable to the F127, but with shorter EO blocks since the P103 apparently shows two hard gel states in two different temperature regions.…”

Influence of a hydrophobic diol on the micellar transitions of Pluronic P85 in aqueous solution

“…Gelations at lower concentrations and higher temperatures (about 10 • C below the CP) for some copolymers have been reported. Park et al [27] have discussed two gel states of a triblock copolymer P103. Bohorquez et al [28] have discussed temperature induced gelation in Pluronic F127.…”

Phase behavior of the Pluronic P103/water system in the dilute and semi-dilute regimes

“…At higher concentrations and temperatures these copolymers form a variety of lyotropic liquid crystals [24,25]. The phase diagrams of aqueous solutions of Pluronics have been obtained by dynamic light scattering (DLS) [12][13][14]26], static light scattering (SLS) [12,13,15], small-angle neutron scattering (SANS) [3,15,17,18,26,27], small-angle X-ray scattering (SAXS), and 1 H NMR spectroscopy [28], ultrasonic speed measurements and densimetry [29][30][31], differential scanning calorimetry (DSC), low shear viscometry, and light transmission experiments [29] as well as dynamic-mechanical rheometry [3,[12][13][14][15]26,27]. The phase behavior of Pluronics has been also predicted using both continuum and lattice mean-field theories [32].…”