Phase behavior of carbon dioxide and polyhedral oligomeric silsesquioxanes (POSS) modified with two different functional groups is studied in the temperature range of 308-323 K, up to 22 MPa. Different than the common types, one of the eight functional groups attached to the Si atoms of these POSS is a CO₂-philic functional group, methacryl, while the rest are branched alkyl chains, either isooctyl (MIOPOSS) or isobutyl (MIBPOSS). Methacrylisobutyl POSS-CO₂ binary system exhibits pressure-induced melting temperature depression. Both molecules have higher solubilities in scCO₂ compared to their counterparts with single type of functionality, octaisobutyl POSS, isooctyl POSS and methacryl POSS. The measured highest solubility of MIBPOSS is 0.006 mole fraction at 323 K and 16.8 MPa, while it is 0.0017 mole fraction at 323 K and 22.1 MPa for MIOPOSS. Various density-based semi-empirical models used to model the solubility data gave good correlations with AARD of about 4%.

研究了在两个最大官能度高达308 MPa的308-323 K温度范围内，用两个不同的官能团修饰的二氧化碳和多面体低聚倍半硅氧烷（POSS）的相行为。与常见类型不同，与这些POSS的Si原子相连的八个官能团之一是亲CO ₂官能团甲基丙烯酸，其余为支链烷基链，即异辛基（MIOPOSS）或异丁基（MIBPOSS）。甲基丙烯酸异丁酯POSS-CO ₂二元体系表现出压力诱导的熔融温度降低。两种分子在scCO _2中均具有较高的溶解度与具有单一功能的同类产品相比，八异丁基POSS，异辛基POSS和甲基丙烯酸POSS。在323 K和16.8 MPa下测得的MIBPOSS最高溶解度为0.006摩尔分数，而对于MIOPOSS，在323 K和22.1 MPa下为0.0017摩尔分数。用于对溶解度数据进行建模的各种基于密度的半经验模型与约4％的AARD具有良好的相关性。