Poly(1-methyl-1,4-butanediol-1,4-diyl/2,3,4trihydro- 5-methylfuran-2,5-diyl) was prepared by epoxidation of deproteinized natural rubber with m-chloroperbenzoic acid followed by hydrolysis with sulfuric acid. Characterization of the resulting product was performed through FT-IR, (1)H NMR, and (13)C NMR spectroscopies. All signals appearing in the (1)H and (13)C NMR spectra were assigned by distortionless enhancement by polarization transfer (DEPT), quaternary carbon observation (QUAT), correlation spectroscopy (COSY), and heteronuclear multiple quantum correlation (HMQC) measurements. After proving the primary structure of the product, one pot synthesis of poly(1-methyl-1,4-butanediol- 1,4-diyl/2,3,4-trihydro-5-methylfuran-2,5-diyl) from deproteinized natural rubber latex was carried out with peracetic acid and 2-propanol. The resulting product was characterized by (1)H NMR spectroscopy on the basis of the assignments established in this study, and its gas permeability was measured for a practical application as a film. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122: 3423-3429, 2011