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首页> 美国卫生研究院文献>Materials >Poly(Urethane-Acrylate) Aerogels via Radical Polymerization of Dendritic Urethane-Acrylate Monomers
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Poly(Urethane-Acrylate) Aerogels via Radical Polymerization of Dendritic Urethane-Acrylate Monomers

机译：树枝状氨基甲酸酯-丙烯酸酯单体的自由基聚合反应制备的聚（氨基甲酸酯-丙烯酸酯）气凝胶

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The purpose of this work was to investigate the effect of multifunctionality on material properties of synthetic polymer aerogels. For this purpose, we present the synthesis and characterization of monolithic dendritic-type urethane-acrylate monomers based on an aliphatic/flexible (Desmodur N3300), or an aromatic/rigid (Desmodur RE) triisocyanate core. The terminal acrylate groups (three at the tip of each of the three branches, nine in total) were polymerized with 2,2′-azobis(isobutyronitrile) (AIBN) via free radical chemistry. The resulting wet-gels were dried with supercritical fluid (SCF) CO2. Aerogels were characterized with ATR-FTIR and solid-state 13C NMR. The porous network was probed with N2-sorption and scanning electron microscopy (SEM). The thermal stability of aerogels was studied with thermogravimetric analysis (TGA). Most aerogels were macroporous materials (porosity > 80%), with high thermal stability (up to 300 °C). Aerogels were softer at low monomer concentrations and more rigid at higher concentrations. The material properties were compared with those of analogous aerogels bearing only one acrylate moiety at the tip of each branch and the same cores, and with those of analogous aerogels bearing norbornene instead of acrylate moieties. The nine-terminal acrylate-based monomers of this study caused rapid decrease of the solubility of the growing polymer and made possible aerogels with much smaller particles and much higher surface areas. For the first time, aliphatic/flexible triisocyanate-based materials could be made with similar properties in terms of particle size and surface areas to their aromatic/rigid analogues. Finally, it was found that with monomers with a high number of crosslinkable groups, material properties are determined by multifunctionality and thus aerogels based on 9-acrylate- and 9-norbornene-terminated monomers were similar. Materials with aromatic cores are carbonizable with satisfactory yields (20–30% w/w) to mostly microporous materials (BET surface areas: 640–740 m2 g−1; micropore surface areas: 360–430 m2 g−1).
机译：这项工作的目的是研究多功能性对合成聚合物气凝胶材料性能的影响。为此，我们提出了基于脂肪族/柔性（Desmodur N3300）或芳香族/刚性（Desmodur RE）三异氰酸酯核的整体树状型聚氨酯丙烯酸酯单体的合成与表征。通过自由基化学将末端丙烯酸酯基团（三个分支的每个末端的三个，总共九个）与2,2'-偶氮二（异丁腈）（AIBN）聚合。用超临界流体（SCF）CO 2干燥所得的湿凝胶。气凝胶用ATR-FTIR和固态 13 C NMR进行了表征。用N 2吸附和扫描电子显微镜（SEM）探测多孔网络。通过热重分析（TGA）研究了气凝胶的热稳定性。大多数气凝胶是大孔材料（孔隙度> 80％），具有很高的热稳定性（最高300°C）。气凝胶在低单体浓度下较软，而在较高浓度下则较硬。将材料性能与在每个分支的尖端仅具有一个丙烯酸酯部分且具有相同核心的类似气凝胶的材料性能，以及与具有降冰片烯而不是丙烯酸酯部分的类似气凝胶的材料性能进行比较。这项研究的基于九末端丙烯酸酯的单体导致正在生长的聚合物的溶解度迅速降低，并使得具有更小颗粒和更高表面积的气凝胶成为可能。首次可以制备基于脂肪族/柔性三异氰酸酯的材料，其颗粒大小和表面积与其芳香族/刚性类似物的性质相似。最后，发现对于具有大量可交联基团的单体，材料性能由多功能性决定，因此基于9-丙烯酸酯和9-降冰片烯封端的单体的气凝胶是相似的。具有芳香核的材料可以碳化，大部分微孔材料（BET表面积：640–740 m 2 g -1 ）具有令人满意的碳化率（20–30％w / w）；微孔表面积：360–430 m 2 g -1 ）。

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