Evaporation kinetics in macroporous polymeric supports evaluated by relaxation measurements

E. V. SILLETTA; C. G. GÓMEZ; M. C. STRUMIA; G. A. MONTI; R. H. ACOSTA

Río de Janeiro

Congreso; 18th International Society of Magnetic Resonance Meeting; 2013

ISMAR

Macroporous polymer beads present a permanent well-developed porous structure in the dry state, and have a wide range of applications such as support for catalysts, immobilization of enzymes, HPLC columns, liberation of active substances, or adsorbents (1). Their porous structure improves the diffusion of different solutes through the network. These networks have particular properties as high degree of crosslinking and rigid structure both in swollen and dry state, turning the study of their synthesis conditions of considerable interest. The properties of the polymer mesh change radically due to swelling, a process that strongly depends on the mesh structure; therefore, changes in the content a selected cross-linker (ethylene glycol dimethacrylate-EGDMA) percentage are studied (3).Evaporation kinetics of swelling liquid molecules (L) distributed in the network show a different interaction with itself (L-L) compared to those liquid molecules adsorbed to the polymer chain (L-P). In the first case the evaporation kinetics present a zero order decay; while in the second a first order decay is present (2).Therefore, monitoring the kinetics of evaporation renders direct information of the swelling process (4). We use 1H-CPMG sequences to measure the distribution of transverse relaxation times ofpolar and non-polar solvents contained in the matrices. As non-polar solvents do not interact with the network, information of the unperturbed porous system is obtained. On the other hand,polar solvents present theL-P interactionsthat compared to L-L provide information on the swelling process. 1. Kristensen TE, Vestli K, Fredriksen KS, Hansen T, Org. Lett. 2009, 11: 2968-2971. 2. Errede L., Kueker MJ, J PolymChem Ed 1988; 26:3375-3380. 3. C.G. Gomez, M. Strumia;Journalof Polymer Science: Part A: Polymer Chemistry46, 2557?2566(2008). 4. C.G. Gomez, G. Pastrana, D. Serrano, E. Zuzek, M.A. Villar, M.C. Strumia, Polymer2012, 53, 2949-2955.