Laves Phase Field in a Diblock Copolymer Alloy
Laves Phase Field in a Diblock Copolymer Alloy
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DOI：
10.1021/acs.macromol.2c00346
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发表时间：
2022-03
期刊：
影响因子：
5.5
通讯作者：
Benjamin R. Magruder;So Jung Park;Ryan P. Collanton;F. Bates;K. Dorfman
中科院分区：
文献类型：
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作者：
Benjamin R. Magruder;So Jung Park;Ryan P. Collanton;F. Bates;K. Dorfman
Laves相是一类四面体密排的Frank-Kasper相，具有AB 2化学计量比。虽然这些相在各种金属合金中表现为金属间化合物，但由于大A颗粒和小B颗粒之间的优选体积的显著差异，在可重构软物质中稳定Laves相是具有挑战性的。令人惊讶的是，也许概念上最简单的方法-将两个具有不相容核心嵌段的二嵌段混合-尚未被探索。利用自洽场理论，我们预测在AB/B′C二嵌段共聚物共混物的共晶相图中，如果（i）AB和B′ C二嵌段共聚物的选择使得它们的纯熔体产生具有所需Laves相的颗粒体积比的bcc相和（ii）A和C嵌段之间的排斥足够强以使胶束之间的混合最小化，则Laves相应该作为相场出现。这种二嵌段“合金化”方法产生的相行为非常类似于产生金属间化合物的金属合金中产生的相行为，并且应该提供相对简单的合成路线来产生软Frank-Kasper相，这是通过常规的基于聚合物的方法难以实现的。
Laves phases are a class of tetrahedrally close-packed Frank–Kasper phases withAB2stoichiometry. While these phases appear as intermetallic line compounds in a variety of metallic alloys, it is challenging to stabilize Laves phases in reconfigurable soft matter because of the substantial difference in preferred volume between the largeAparticles and smallBparticles. Surprisingly, perhaps the conceptually simplest approach─blending two diblocks with incompatible core blocks─has not been explored yet. Using self-consistent field theory, we predict that a Laves phase should emerge as a phase field in the eutectic phase diagram of an AB/B′C diblock copolymer blend if (i) the AB and B′C diblock copolymers are selected such that their neat melts produce bcc phases with the particle volume ratio of the desired Laves phase and (ii) the repulsion between A and C blocks is sufficiently strong to minimize mixing between micelles. This diblock “alloying” approach produces phase behavior that closely mimics that arising in intermetallic compound-producing metal alloys and should provide a relatively simple synthetic route to produce soft Frank–Kasper phases that are challenging to achieve by conventional polymer-based approaches.