Lower Critical Ordering Transition of an All-Hydrocarbon Polynorbornene Diblock Copolymer,ACS Macro Letters

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Lower Critical Ordering Transition of an All-Hydrocarbon Polynorbornene Diblock Copolymer
ACS Macro Letters ( IF 5.1 ) Pub Date : 2017-07-18 00:00:00 , DOI: 10.1021/acsmacrolett.7b00443
William D. Mulhearn ₁ , Richard A. Register ₁

Affiliation

A new diblock copolymer chemistry, hydrogenated poly(n-hexyl norbornene)-block-poly(cyclohexyl norbornene), is demonstrated to undergo a lower critical ordering transition (LCOT) upon heating. Diblock copolymers exhibiting LCOT behavior are rare, and to our knowledge, the system described in this work is the first all-hydrocarbon species to do so. Furthermore, the tendency toward demixing for this polymer at high temperatures does not arise from a large free volume mismatch between its components, the mechanism most commonly invoked to explain an LCOT in block copolymers or a lower critical solution temperature in polymer blends. We compare the LCOT-type polymer with a homologous family of other norbornene-based polymers exhibiting the more common upper critical ordering transition and demonstrate that the mismatch in thermal expansion coefficients between blocks, which is related to the mismatch in free volumes, does not dictate the type of phase behavior.

中文翻译：

全烃类聚降冰片烯二嵌段共聚物的较低临界有序转变

一种新的双嵌段共聚物化学，氢化聚（正己基降冰片烯）-嵌段-聚（环己基降冰片烯）被证明在加热时经历较低的临界有序转变（LCOT）。表现出LCOT行为的二嵌段共聚物非常罕见，据我们所知，这项工作中描述的系统是第一个这样做的全烃物种。此外，这种聚合物在高温下易于混合的趋势并不是由其组分之间的自由体积大失配引起的，这种机理最常被用来解释嵌段共聚物中的LCOT或聚合物共混物中较低的临界溶液温度。我们将LCOT型聚合物与表现出更常见的上临界序跃迁的其他降冰片烯基聚合物的同源家族进行了比较，并证明了嵌段之间的热膨胀系数不匹配，这与自由体积的不匹配有关，

更新日期：2017-07-18

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