Exactly Defined Half-Stemmed Polymer Lamellar Crystals with Precisely Controlled Defects' Locations

We describe highly unconventional situations in which the polymer chain ends remain trapped in and are located in the middle of the lamellar crystal core as defects. Such structures are observed in giant molecular shape amphiphiles constructed by a polyhedral silsesquioxane (POSS) nanoparticle tethered with a poly(ethylene oxide) (PEO) tail. The cross-sectional area of the POSS located on the PEO lamellar surfaces imposes that the crystalline, chain-folded PEO tails generate a surface area that is at least comparable to the POSS requirements. Metastable PEO crystal structures with 1.5, 2, and 2.5 stem numbers have been observed with different thermodynamic stabilities.