MONTE-CARLO SIMULATION STUDIES OF CONFORMATIONAL PROPERTIES OF POLYELECTROLYTES WITH MALEIC-ACID UNITS

Conformational properties of polyelectrolyte chain with maleic acid un its (MA polyelectrolyte) are investigated by a mean of Monte Carlo sim ulation. The polyelectrolyte chains are modeled as a self-avoiding wal k on tetrahedral lattice with charges fixed. The each charge interacts through Debye-Huckel potential and attraction energy from hydrogen bo nding between un-ionized and ionized carboxyl groups in short-range. M ean-square end-to-end distance, [R(2)], mean-square radius of gyration , [S-2], and mean conformational energy, [E], are simulated as a funct ion of degree of polymerization (N) and dissociation (alpha), and salt concentration (C-S). The dependence of [R(2)] and [S-2] On N shows th at MA polyelectrolyte chain assumes a rod like conformation at high al pha and low C-S. The simulation results provide an interpretation for characteristic viscometric behavior of MA polyelectrolytes which show a maximum in an intrinsic viscosity nearly at alpha=0.5. The polymer d imensions in the region of alpha less than or equal to 0.5 increases w ith the energy of the hydrogen bonding assumed. The characteristic vis cometric behavior of MA polyelectrolytes is deduced to result from the balance between repulsion from the electrostatic interaction and attr action from the hydrogen bonding in short-range.