Exact results for isolated sticky chains

Exact results for the thermodynamic properties of isolated freely jointed sticky trimers and tetramers are obtained by taking appropriate limits on the exact results for a single square-well chain. Two new methods for approximating the square-well potential by a sticky potential are suggested. These new methods extend greatly the range of square-well widths over which the thermodynamic properties of a single square-well chain can be estimated accurately in terms of the corresponding properties of a single sticky chain.