Sane Amporn, Thies Mark C
Center for Advanced Engineering Fibers and Films, Department of Chemical Engineering, Clemson University, Clemson, South Carolina 29634-0909, USA.
J Phys Chem B. 2005 Oct 27;109(42):19688-95. doi: 10.1021/jp0581072.
Organic nanoparticles of a fluorinated tetraphenylporphyrin (TBTPP) were produced by rapid expansion of supercritical CO(2) solutions into both air (RESS) and an aqueous receiving solution containing a stabilizing agent (RESOLV). The effect of processing conditions on both particle size and form was investigated. The size of the porphyrin nanoparticles produced via RESS increased in a well-behaved manner from 40 to 80 nm as the preexpansion temperature increased from 40 to 100 degrees C, independent of porphyrin concentration, degree of saturation, and preexpansion pressure. RESOLV of TBTPP + CO(2) solutions was investigated both for minimizing particle growth in the free jet and for the prevention of particle agglomeration. Anionic, nonionic, and polymeric stabilizing agents for the aqueous receiving solution were considered. Expansion into a 0.05 wt % SDS solution produced nanorods 50-100 nm in diameter with an aspect ratio of 3-5. RESOLV in a 0.025 wt % Pluronic F68 solution produced well-dispersed, individual, spherical nanoparticles averaging 23 +/- 10 to 32 +/- 10 nm in diameter, independent of the rapid expansion processing conditions selected. Furthermore, the resulting nanoparticle suspensions were stable, with particle sizes remaining unchanged after several months. However, some particle agglomeration occurred at higher (i.e., 1 wt % TBTPP in CO(2)) concentrations. Contact-angle measurements on solid TBTPP compacts with the tested receiving solutions indicate that a moderate wetting agent such as Pluronic F68 is most effective for preserving the size and form of the porphyrin nanoparticles produced by RESOLV. Finally, the fact that nanoparticles are produced from RESS of TBTPP, in contrast with other organics for which microparticles are produced, can be explained in terms of the high melting point of TBTPP (388 degrees C), which results in a solid-state diffusion coefficient of TBTPP low enough so that particle coalescence is significantly reduced in the free jet.
通过将超临界CO₂溶液快速膨胀到空气中（RESS）以及含有稳定剂的水接收溶液中（RESOLV），制备了氟化四苯基卟啉（TBTPP）的有机纳米颗粒。研究了加工条件对颗粒尺寸和形态的影响。随着预膨胀温度从40℃升高到100℃，通过RESS制备的卟啉纳米颗粒尺寸以良好的方式从40nm增加到80nm，与卟啉浓度、饱和度和预膨胀压力无关。对TBTPP + CO₂溶液进行RESOLV研究，以最小化自由射流中的颗粒生长并防止颗粒团聚。考虑了用于水接收溶液的阴离子、非离子和聚合物稳定剂。膨胀到0.05 wt%的SDS溶液中产生了直径为50 - 100nm、长径比为3 - 5的纳米棒。在0.025 wt%的普朗尼克F68溶液中进行RESOLV产生了分散良好、单个的球形纳米颗粒，平均直径为23±10至32±10nm，与所选的快速膨胀加工条件无关。此外，所得的纳米颗粒悬浮液是稳定的，颗粒尺寸在几个月后保持不变。然而，在较高浓度（即CO₂中1 wt%的TBTPP）下会发生一些颗粒团聚。对固体TBTPP压块与测试的接收溶液进行接触角测量表明，一种适度的润湿剂如普朗尼克F68对于保持RESOLV制备的卟啉纳米颗粒的尺寸和形态最有效。最后，与其他产生微粒的有机物相比，TBTPP通过RESS产生纳米颗粒这一事实，可以用TBTPP的高熔点（388℃）来解释，这导致TBTPP的固态扩散系数足够低，从而在自由射流中颗粒聚结显著减少。
