Here we demonstrate a unique two-dimensional polymer synthesis through topochemical polymerization via polymer crystal engineering, which is useful for controlling and designing the polymerization reactivity as well as the polymer chain and crystal structures. We have succeeded in the synthesis of a sheet polymer through the polymerization of alkylenediammonium (ZZ)-muconate as a multifunctional 1,3-diene monomer in the crystalline state under the irradiation of LJV and gamma-rays or upon heating in the dark. The photopolymerization reactivity of several muconates and the structural control of the obtained polymer are described. The stereochemical structure of the polymer and the polymerization mechanism are discussed on the basis of the results of IR and NMR spectroscopy, thermogravimetric measurements, and solid-state hydrolysis for the transformation into poly(muconic acid). (C) 2004 Wiley Periodicals, Inc.