We investigated the temperature-dependent phase behavior and interaction parameter of polyethylene-based multiblock copolymers with pendant ionic groups. These step-growth polymers contain short polyester blocks with a single Li⁺SO₃^– group strictly alternating with polyethylene blocks of x-carbons (PESxLi, x = 12, 18, 23). At room temperature, these polymers exhibit layered morphologies with semicrystalline polyethylene blocks. Upon heating above the melting point (∼130 °C), PES18Li shows two order-to-order transitions involving Ia3̅d gyroid and hexagonal morphologies. For PES12Li, an order-to-disorder transition accompanies the melting of the polyethylene blocks. Notably, a Flory–Huggins interaction parameter was determined from the disordered morphologies of PES12Li using mean-field theory: χ(T) = 77.4/T + 2.95 (T in Kelvin) and χ(25 °C) ≈ 3.21. This ultrahigh χ indicates that the polar ionic and nonpolar polyethylene segments are highly incompatible and affords well-ordered morphologies even when the combined length of the alternating blocks is just 18–29 backbone atoms. This combination of ultrahigh χ and short multiblocks produces sub-3-nm domain spacings that facilitate the control of block copolymer self-assembly for various fields of study, including nanopatterning.

中文翻译：

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具有悬垂离子基团的超高 χ 多嵌段共聚物的亚 3 纳米域间距

我们研究了具有离子侧基的聚乙烯基多嵌段共聚物的温度依赖性相行为和相互作用参数。这些逐步增长的聚合物包含具有单个 Li ⁺ SO ₃ ^-基团的短聚酯嵌段，与x碳的聚乙烯嵌段(PES x Li, x = 12, 18, 23)严格交替。在室温下，这些聚合物表现出具有半结晶聚乙烯嵌段的层状形态。当加热到熔点（~130 °C）以上时，PES18Li 显示出两个有序到有序的转变，涉及Ia 3̅ d陀螺和六边形形态。对于 PES12Li，从有序到无序的转变伴随着聚乙烯嵌段的熔化。值得注意的是，弗洛里-哈金斯相互作用参数是使用平均场理论从 PES12Li 的无序形态确定的：χ( T ) = 77.4/ T + 2.95 ( T in Kelvin) 和 χ(25 °C) ≈ 3.21。这种超高的 χ 表明极性离子和非极性聚乙烯链段高度不相容，即使交替嵌段的组合长度仅为 18-29 个主链原子，也能提供有序的形态。这种超高 χ 和短多嵌段的组合产生了亚 3 纳米的域间距，有助于控制各种研究领域的嵌段共聚物自组装，包括纳米图案化。