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The block polyethers PEO-PPO-ph-PPO-PEO (BPE) and PPO-PEO-ph-PEO-PPO (BEP) are synthesized by anionic polymerization using bisphenol A as initiator. Compared with Pluronic P123, the aggregation behaviors of BPE and BEP at an air/water interface are investigated by the surface tension and dilational viscoelasticity. The molecular construction can influence the efficiency and effectiveness of block polyethers in decreasing surface tension. BPE has the most efficient ability to decrease surface tension of water among the three block polyethers. The maximum surface excess concentration (Γ(max)) of BPE is larger than that of BEP or P123. Moreover, the dilational modulus of BPE is almost the same as that of P123, but much larger than that of BEP. The molecular dynamics simulation provides the conformational variations of block polyethers at the air/water interface.

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Linear block polyethers, i.e., poly(ethylene oxide) (PEO)-poly(propylene oxide) (PPO)-PEO (LPE), and X-shaped block polyethers, i.e., PEO-PPO-PEO (TPE), with same EO/PO ratios and molecular masses were synthesized by anionic polymerization. The aggregation behaviors at air/water and n-heptane/water interfaces were systematically studied. The results show that LPE is more efficient at decreasing the surface tension of water and n-heptane than TPE is. The dynamic interfacial tension curves indicate that the lag-time of the adsorption of the block polyethers at the n-heptane/water interface is smaller than that at the air/water surface, implying that immersion of the PO groups in the oil phase is more energetically favorable than immersion in the air phase. The oil molecules can insert into the adsorption layer, and hydrophobic interactions between oil molecules and PO moieties lead to a relatively ordered arrangement of adsorbed polyether molecules. At the n-heptane/water interface, diffusion of the block polyethers is faster than that at the air/water surface. The dilatational elasticity at the n-heptane/water interface is much higher than that at the air/water surface.