Koga Tadanori, Jerome J, Rafailovich M H, Chu B, Douglas J, Satija S
Chemical and Molecular Engineering Program, Department of Materials Science and Engineering, Stony Brook University, Stony Brook, New York 11794-2275, USA.
Adv Colloid Interface Sci. 2006 Dec 21;128-130:217-26. doi: 10.1016/j.cis.2006.11.020. Epub 2007 Jan 17.
This paper reviews our recent experimental results that address the effects of solvent density inhomogeneities in supercritical carbon dioxide (scCO(2)) on polymer thin film processing. The key phenomenon is excess sorption of CO(2) molecules into polymer thin films even when the bulk miscibility with CO(2) is very poor. We have found that the amount of the excess sorption is attributed to the large density fluctuations in scCO(2) near the critical point. Further, taking advantage of the vitrification process of polymer chains through quick evaporation of CO(2), we can preserve the "expanded" structures as they are. The resultant films have large degree of molecular-level porosity that is very useful in producing coatings with low dielectric constants, enhanced adhesion, and metallization properties. These characteristics can be achieved in an environmentally "green" manner, without organic solvents, and are not specific to any class of polymers.
本文综述了我们最近的实验结果，这些结果涉及超临界二氧化碳（scCO₂）中溶剂密度不均匀性对聚合物薄膜加工的影响。关键现象是即使聚合物与CO₂的本体混溶性很差，CO₂分子仍会过量吸附到聚合物薄膜中。我们发现过量吸附的量归因于临界点附近scCO₂中的大密度波动。此外，利用CO₂快速蒸发使聚合物链玻璃化的过程，我们可以保持“膨胀”结构不变。所得薄膜具有很大程度的分子级孔隙率，这对于生产具有低介电常数、增强附着力和金属化性能的涂层非常有用。这些特性可以通过环境友好的“绿色”方式实现，无需有机溶剂，且不特定于任何一类聚合物。
