Enhanced Surface Interaction of Water Confined in Hierarchical Porous Polymers Induced by Hydrogen Bonding

E.V. SILLETTA; M.I. VELASCO; C.G. GOMEZ; M.C. STRUMIA; S. STAPF; C. MATTEA; G.A. MONTI; R.H. ACOSTA

LANGMUIR

AMER CHEMICAL SOC

Lugar: Washington; Año: 2016 vol. 32 p. 7427 - 7434

0743-7463

Hierarchical porous polymer systems are increasinglyapplied to catalysis, bioengineering, or separation technology because ofthe versatility provided by the connection of mesopores with percolatingmacroporous structures. Nuclear magnetic resonance (NMR) is asuitable technique for the study of such systems as it can detect signalsstemming from the confined liquid and translate this information intopore size, molecular mobility, and liquid−surface interactions. We focuson the properties of water confined in macroporous polymers ofethylene glycol dimethacrylate and 2-hydroxyethyl methacrylate [poly-(EGDMA-co-HEMA)] with different amounts of cross-linkers, in whicha substantial variation of hydroxyl groups is achieved. As soft polymerscaffolds may swell upon saturation with determined liquids, the use ofNMR is particularly important as it measures the system in itsoperational state. This study combines different NMR techniques toobtain information on surface interactions of water with hydrophilic polymer chains. A transition from a surface-inducedrelaxation in which relaxivity depends on the pore size to a regime where the organic pore surface strongly restricts waterdiffusion is observed. Surface affinities are defined through the molecular residence times near the network surface.