bells (see, e.g., (7)(8)(9)(10)(11)(12)). One of the focuses of these studies NVT Monte Carlo simulations are reported for chemically assowas the equation of state of 2D systems. Very recently, Zhou ciating two-dimensional fluids which can polymerize for certain et al. (13) applied thermodynamic perturbational theory for interaction energies, due to the presence of two attractive sites per planar dumbbells and emphasized the necessity of simulation monomeric hard disc. The sites are fixed inside a hard core at a data for two-dimensional chain fluids. The lack of exact, given valence angle and mutual penetration of discs is permitted.
i.e., simulational, results does not permit progress in devel-
The type of products of polymerization depends on the parameters oping the equation of state for these systems. In particular, of the model; we observe the formation of small associates, as well a set of problems arising in the description of phase transias of extended chains, bent chains, and rings with different number tions in 2D systems with inclusion of the effects of chemical of monomers. The values of valence angles and of association energy are of primary importance. The dependence of the struc-association cannot be solved at present.
tural properties of the model on fluid density and association en-
We have initiated the study of chemically associating 2D ergy is investigated. We performed detailed analysis of the clusters fluids in our recent work ( 14), applying the Monte Carlo formed due to association in terms of fractions of singly and doubly simulational technique to the 2D version of the model of bonded particles, of average numbers of chains and rings, and of Cummings and Stell for chemical association (15). In this their size. We also obtain the average end to end distance, the model, the associative interaction is in the form of a spheriradius of gyration, and the persistent length of the products of cally symmetric attractive shell located to permit mutual polymerization. The pressure is calculated from the density propenetration of monomers. Depending on the choice of the files of particles of the polymerizing fluid near a hard ''wall.'' The bonding length, dimers, trimers, or chains can be formed.
data can be used to develop the equation of state for chemically In the extreme case of bonding length close to the diameter associating two-dimensional fluids. α§ 1997 Academic Press of the monomer, vulcanization of monomers may occur.