In a paper published in 1931, Polyakov reported the effects of presence of different solvents (benzene, toluene and xylene) on the silica pore structure during drying a newly prepared silica. When H2SO4 was used as the polymerization initiator (acidifying agent), a positive correlation was found between surface areas, e.g. load capacities, and the molecular weights of the respective solvents. Later on, in 1949 Dickey reported the polymerization of sodium silicate in the presence of four different dyes (namely methyl, ethyl, n-propyl and n-butyl orange). The dyes were subsequently removed, and in rebinding experiments it was found that silica prepared in the presence of any of these "pattern molecules" would bind the pattern molecule in preference to the other three dyes. Shortly after this work had appeared, several research groups pursued the preparation of specific adsorbents using Dickey's method. Some commercial interest was also shown by the fact that Merck patented a nicotine filter, consisting of nicotine imprinted silica, able to adsorb 10.7% more nicotine than non-imprinted silica. The material was intended for use in cigarettes, cigars and pipes filters. Shortly after this work appeared, molecular imprinting attracted wide interest from the scientific community as reflected in the 4000 original papers published in the field during for the period 1931–2009 (from Scifinder). However, although interest in the technique is new, commonly the molecularly imprinted technique has been shown to be effective when targeting small molecules of molecular weight <1000. Therefore, in following subsection molecularly imprinted polymers are reviewed into two categories, for small and big templates.
