Multiwalled carbon nanotube network (MWCNT-N)/poly(methyl methacrylate) (PMMA) composite is prepared by solution radical polymerization. The entangled multiwall carbon nanotube network (MWCNT-N) is obtained by vacuum filtration and functionalized by allyl isocyanate to form polymerizable vinyl groups on a nanotube surface. The solution polymerization binds PMMA covalently to these groups and yields MWCNT-N/PMMA composite manifesting electrical conduction and selective chemical vapor sensing. The latter property is evaluated in terms of affinity of organic solvent vapor and PMMA polarities. It is found that the affinity of acetone polarity with polarity of PMMA improves significantly the sensitivity of the composite to this solvent while the sensitivity to methanol is the same and to iso-pentane even decreased in comparison with the corresponding property of MWCNT-N. The composite selective response is favorable for a possible composite use as a sensing element and/or vapor switch. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012