Use of Polymeric Catalysts in the Pore-Size-Specific Functionalization of Porous Polymers

The size-restricted access of molecules to cavities of different sizes has been used in the demonstration of size-selective modification of a porous material. The epoxide functionalities of macroporous poly(glycidyl methacrylate-co-ethylene dimethacrylate) beads are hydrolyzed to diol groups in the presence of an acid catalyst. While sulfuric acid catalyzes hydrolysis of all epoxide groups, bulkier catalysts such as poly(styrenesulfonic acid) only cause hydrolysis to occur within pores large enough to accommodate them. As a result, porous materials containing two types of functionalities segregated respectively in pores larger and smaller than the catalyst are obtained. Similar size-specific functionalization has been achieved with macroporous beads containing benzylidene or tetrahydropyranyl ether groups.