Order−Order Transition in a Rod−Coil Diblock Copolymer Induced by Supercritical CO2
Order−Order Transition in a Rod−Coil Diblock Copolymer Induced by Supercritical CO2
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DOI：
10.1021/ma1023704
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发表时间：
2011-03
期刊：
影响因子：
5.5
通讯作者：
Lingying Shi;Zhihao Shen;Xinghe Fan
中科院分区：
文献类型：
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作者：
Lingying Shi;Zhihao Shen;Xinghe Fan
我们合成了一系列具有良好定义的棒-线圈嵌段共聚物（bcp），聚（二甲基硅氧烷）-b-聚{2,5-双[（4-甲氧基苯基）氧羰基]苯乙烯}(PDMS-b- pmpcs)，含有一个亲CO2嵌段PDMS，我们用小角x射线散射研究了它们在体和超临界CO2 （scCO2）处理后的相结构。当PDMS （fPDMS）的体积分数降至18%时，BCP的纳米结构从片层（LAM）转变为六边形填充柱（HEX）。虽然PMPCS块体在scCO2中的玻璃化转变温度（Tg）在我们的实验中无法直接测量，但根据SAXS结果估计，在110 bar时scCO2中的玻璃化转变温度显著降低。更重要的是，在我们的实验条件下，我们观察到scCO2在BCP相图中位于HEX- LAM相边界附近的HEX- LAM结构BCP中诱导的HEX- LAM序-序转变。OOT可归因于线圈块体体积分数和有效载荷的增加。
We synthesized a series of well-defined rod−coil block copolymers (BCPs), poly(dimethylsiloxane)-b-poly{2,5-bis[(4-methoxyphenyl)oxycarbonyl]styrene} (PDMS-b-PMPCS), containing a CO2-philic block PDMS, and we studied their phase structures in bulk and after treatment with supercritical CO2 (scCO2) using small-angle X-ray scattering. The nanostructure of the BCP changed from lamellae (LAM) to hexagonally packed cylinders (HEX) when the volume fraction of PDMS (fPDMS) decreased to ∼18%. Although the glass transition temperature (Tg) of the PMPCS block in scCO2 could not be measured directly in our experiment, it significantly decreased in scCO2 at 110 bar as estimated from SAXS results. More significantly, we observed a HEX−LAM order−order transition induced by scCO2 in a HEX-structured BCP which was located close to the HEX−LAM phase boundary in the BCP phase diagram under our experimental conditions. The OOT could be attributed to increases in both the volume fraction of the coil block and the effective i...