Macroporous poly(ionic liquid) and poly(acrylamide) monoliths from CO2-in-water emulsion templates stabilized by sugar-based surfactants
作者:Cédric Boyère、Audrey Favrelle、Alexandre F. Léonard、Frank Boury、Christine Jérôme、Antoine Debuigne
DOI:10.1039/c3ta11073g
日期:——
Highly interconnected poly(acrylamide) (PAM) and poly(vinylimidazolium) (PVIm) porous monoliths were templated by carbon dioxide-in-water (CO2/W) high internal phase emulsions (HIPEs), a toxic-solvent free process. A range of sugar-based fluorinated surfactants prepared by chemoenzymatic synthesis were used as emulsifiers. Both the concentration and the structure of the surfactants, especially the length of their CO2-philic part and of their spacer between the sugar head and the tail, were found to strongly affect the cellular structure and morphology of the PAM polyHIPEs, i.e. the size of pores and cells. A mannose derivative bearing a chain ranging from 6 to 10 perfluorinated carbons and a long spacer emerged as the best stabilizer, leading to a porous monolith with average pores and cell sizes (about 2.6 μm and 5–10 μm, respectively) among the lowest reported for polyHIPEs produced from CO2/W emulsions. The same template then served for the preparation of the first macroporous poly(ionic liquid) (PIL) polyHIPE by using 1-vinyl-3-ethylimidazolium bromide as the monomer. Shrinkage of the final material was prevented by adjusting the divinylimidazolium crosslinker content. The resulting low density polyHIPE exhibits small spherical cells (∼5 μm) connected by numerous small pores (∼2 μm), confirming that the CO2/W HIPE templating methodology based on fluorinated glycosurfactants is a technique of choice for the preparation of macroporous PILs.
高度互联的聚丙烯酰胺(PAM)和聚(乙烯咪唑)(PVIm) 多孔单体通过二氧化碳-水(CO2/W)高内部相乳液(HIPEs)模板制备,该过程不使用有毒溶剂。使用了一系列通过化学酶合成制备的基于糖的氟化表面活性剂作为乳化剂。表面活性剂的浓度和结构,特别是其CO2亲和部分的长度以及糖头和尾之间的间隔,显著影响了PAM聚HIPE的细胞结构和形态,即孔和细胞的大小。一个具有6到10个全氟碳链和长间隔的甘露糖衍生物表现为最佳稳定剂,导致其制得的多孔单体具有相对较低的平均孔尺寸和细胞尺寸(约2.6 μm和5–10 μm),是从CO2/W乳液中生产的聚HIPE中报告的最低值之一。相同的模板随后用于制备第一种大孔聚离子液体(PIL)聚HIPE,采用1-乙烯基-3-乙基咪唑溴化物作为单体。通过调整二乙烯基咪唑交联剂的含量,防止最终材料的收缩。所得到的低密度聚HIPE展现出小球形细胞(约5 μm),通过众多小孔(约2 μm)相互连接,证实了基于氟化糖表面活性剂的CO2/W HIPE模板方法是制备大孔PIL的首选技术。