Specific Chromatographic Retentions on Polymer Pore Surface of Macroporous Spongy Monoliths

Abstract

We examined chromatographic retention properties of macroporous spongy monolithic columns. Detailed chromatographic evaluations showed that planar compounds were strongly retained on poly(ethylene-co-vinyl acetate)-based monoliths, whereas sterically bulky or hydrophilic compounds were weakly retained. The comparison results with commonly used columns suggested that the specific retention abilities were a result of the differences in the polymer-chain orientation on polymer pore surface.In the past few decades, monolithic columns containing silica or polymer-based materials have been widely developed in the field of liquid chromatographic separation.13 Previously, we reported that the macroporous poly(ethylene-co-vinyl acetate; EVA) spongy monolith having around 10¯m pore size, effectively worked as a separation medium in reversed-phase chromatography. 4 In particular, we showed the possibility for high-throughput separation based on a macroporous structure and the separation selectivity for polyaromatic hydrocarbons.5 In this letter, we describe the basic retention properties of the spongy monolith in point of polymer pore-surface structure. In reversed-phase chromatography, the retention properties can be examined as done in a previous study. 6 In order to compare the retention properties of spongy monolith, columns were evaluated by liquid chromatography and as packed columns with octadecylsilylsilica particles (Sil-C18), ethylene glycol dimethacrylate (EDMA)-based particles, and other spongy monoliths having different contents of vinyl acetate units.11 In this letter, EVA containing 15% poly(vinyl acetate) against polyethylene is represented as EVA15. The spongy monolith prepared from linear low-density polyethylene is represented as PE.Typical chromatograms of columns are shown in Figure 1. The comparison of EVA15 and EVA25 show that the content of vinyl acetate units played a role in determining the hydrophobic retention on spongy monolith. In addition, spongy monoliths provided better peak shape than packed column with EDMAbased particles. It was assumed that the peak tailing occurred because of the micropore structure 7 on EDMA. On the other hand, there were no meso-and micropores in spongy monoliths in our previous study. Therefore, the spongy monolith gave a symmetric peak. Table 1 shows the separation coefficient of planar and sterically bulky solutes with nearly equal hydrophobicity. As shown in Table 1, separation coefficients for naphthalene and biphenyl have no significant differences in each column. In contrast, in the case of other solute combination, spongy monoliths showed selective retention for planar solutes and gave larger separation coefficient than those on EDMA and Sil-C18. Since polymer media has large steric selectivity for a planar solute, the higher planar selectivity of spongy monoliths is noticeable. The results also showed that the selectivity for planar solutes was emphasized in larger molecule such as triphenylene. Figure 2 that shows the comparison of the retention of terpheny...

Effect of Solvents on the Surface Modification of Hydrophilic Macro-Porous Particles with an Ion-Exchange Monomer Having Both Anion and Cation Exchange Groups

“…These observations strongly support the speculative illustration ( Fig. 4) [9,[12][13][14]. A separation factor  (k caffeine / k phenol ) reveals a hydrophilicity of the stationary phase in reversed-phase HPLC.…”

Hybridization of a Macroporous Sponge and Spherical Microporous Adsorbents for High Throughput Separation of Ionic Solutes

“…In our previous studies, we described that EVA-based sponge materials can be used for adsorption media, and have a specific retention ability for polycyclic aromatic hydrocarbons. 17,27 As an easy consideration, DVB and graphite has many aromatic rings; therefore, the interaction between these particles and EVA might be stronger, and thus most of the particles were imported into the backbone. Similarly, EDMA-based particles have a certain degree of affinity with aromatic compounds; 28 resulting EDMA particles were situated on the surface of the EVA backbone.…”

Morphology Control and Metallization of Porous Polymers Synthesized by Michael Addition Reactions of a Multi-Functional Acrylamide with a Diamine

“…Various types of porous polymers have been prepared by polymerization-induced phase separation (vinyl type monomers [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ], click type polymerizations such as epoxy-amine reaction [ 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ], epoxy-thiol reaction [ 35 , 36 , 37 ], thiol-ene/yene [ 38 , 39 , 40 , 41 , 42 , 43 , 44 ], thiol-(meth) acrylate [ 45 , 46 , 47 ]) and temperature induced phase transfer [ 48 , 49 , 50 , 51 , 52 , 53 , …”