  In theory, there exist two extreme forms of substances: pure form and
single-molecule mixture form. Single-molecule mixture form contains a mixture
of molecules that have molecularly different structures. This elusive form has
not yet been explored. Herein, we report a study of single molecule mixture
state by a combination of model construction and mathematical analysis, and a
series of interesting results were obtained. These results provide theoretical
evidence that single-molecule mixture state may indeed exist in realistic
synthetic or natural polymer system.
