Well-developed nano-ribbons composed of isotactic poly(methyl methacrylate) (it-PMMA) were successfully fabricated on mica via a simple solution-casting method. Typical morphologies with about 0.6 nm thickness and 30-40 nm widths, thermal stability, and alternative structural analyses suggested that nano-ribbons were composed of two-dimensional folded chain crystals of it-PMMA. Typically, nano-ribbons were developed by incubating tetrahydrofuran (THF) solutions at 20 degrees C for at least 2 months, more than equi-amounts of water were added to incubated THF solutions, and solutions were cast onto mica. It was found that, after the aforementioned incubation of THF solutions, it-PMMA chains adopted trans-trans (tt) conformations, which are precursors for it-PMMA crystals, suggesting that THF is a unique solvent for it-PMMA. By adding water, a poor solvent for it-PMMA, to THF solutions, it-PMMA aggregates formed with several hundreds of nanometer sizes, further promoting an increase in the population of the tt conformation. Nano-ribbons were similarly formed on silicon wafer substrates, suggesting that hydrophilic substrates were essential for the formation of nano-ribbons. Interestingly, a modulation of the above described method, with the slight evaporation of THF from a THF/water solution before casting onto mica, succeeded in the development of epitaxially adsorbed nano-ribbons. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3098-3110, 2009