Gel permeation chromatography (solid lines) determination of PEG size and polydispersity for PEG 200, 600, 1000, 2000, 3400, and 4600, expressed as the degree of polymerization N. The number and weight average degrees of polymerization and corresponding polydispersity indexes are listed in Table 1. The dashed lines represent theoretical fits to the experimental size distributions assuming either a Schulz (PEG 200, 600, 2000, 3400) or a Tung (PEG 1000, 4600) distribution function, with fitting parameters detailed in Table 1.