  In this work we have reported the pKa values for straight chain (without
branches) oligomers of Acrylic acid using CBS-QB3 gas phase energies with
solvation free energies from CPCM/HF 6-31G(d) and SMD/B3LYP (2df,p). We have
found that the negative log of the first acid dissociation constant decreases
with the chain length. Within a chain, the microscopic pKa for the COOH groups
present at the end of the chain is maximum and minimum for centrally located
COOH groups.
