کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5178304 | 1502489 | 2017 | 5 صفحه PDF | دانلود رایگان |
- Stereocomplexes of PDLA and PDMAEMA-b-PLLA-b-PDMAEMA were successfully observed in ultrathin films (30Â nm).
- The single crystals are hexagonal or triangular depending on the PLLA/PDLA ratio and molecular weight of each species.
- The shift in morphology depends upon the mobility of two species.
When poly(d-lactide) (PDLA) is mixed with poly(l-lactide) (PLLA) of similar molecular weight and crystallized from the melt in ultrathin films (30Â nm), hexagonal single crystals are obtained at the equimolar composition, and triangular single crystals at non-equimolar compositions. Here, stereocomplexes are formed by blending PDLA with a PLLA incorporated as the central block of a triblock copolymer made with poly(2-dimethylaminoethyl methacrylate) (PDMAEMA-b-PLLA-b-PDMAEMA or BAB); the resulting single crystals are studied by in-situ atomic force microscopy. The imbalance between the PDLA and PLLA characteristics, due to the presence of the B blocks of the triblock copolymer, leads to triangular single crystals at equimolar compositions, the hexagonal single crystal morphology being shifted to off-equimolar compositions. The importance of the shift depends upon the A/B ratio and the molecular weight of each species.
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Journal: Polymer - Volume 117, 19 May 2017, Pages 25-29