PLA has caught widely attention because of its biocompatibility and similar mechanical properties with that of poly (styrene). The chiral carbon of PLA gives it a potential to form different crystal structure. Among them, PLA stereocomplex (SC) crystal, is the most attractive system, because of its high melting point (~ 230oC). To understand origins of excellent thermal property of SC, fundamental crystalline structural analysis is necessary. So far, X-ray and electron diffraction analysis has provided packing structure of SC is either R3c or R3c-1, which represent PLLA regularly and alternatively pack with PDLA. Very recently, XRD fiber diffraction analysis supported a different packing model, P3, where PLLA stems randomly pack with either PLLA or PDLA. In this presentation, we investigate packing structure of PLA SC crystals by applying 13C-13C double quantum (DQ) NMR spectroscopy. Local dipolar interaction can provide local packing structure in PLA SC.

Crystal structure of poly(lactic acid) stereocomplex as studied by 13C-13C double quantum NMR

255th National Meeting (2018)

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