Bottlebrush polymers with poly(lactic acid)(PLA) side-chains have potential applications such as drug delivery vehicles because of their biocompatibility and biodegradability. In our study, we synthesized and investigated thermal properties of PLA bottlebrushes and polymer blends with linear PLA. Ring-opening polymerization was initiated by an alcohol terminated norbornene (Nb) in the presence of D,L-lactide to yield NbPLAm (m= 10 � 104, Mw= 2000 � 10000 g/mol). Ring-opening metathesis polymerization (ROMP) of NbPLAm macromonomers resulted in well-defined bottlebrush polymers with poly(norbornene) backbone and grafted PLA side-chains, PNb(PLAm)X, (X= 25 � 200, overall Mw= 65000 � 970000 g/mol) where X denotes the backbone degree of polymerization (DP). Size exclusion chromatography (SEC) confirmed mass content of bottlebrush polymers after ROMP >95% in all cases. The glass transition temperature, Tg, of NbPLAm and PNb(PLAm)X are determined by DSC. The Tg of NbPLAm ranges from 10 � 46 �C with increasing molecular weight, as predicted by the Fox equation. PNb(PLAm)X bottlebrush polymers have an average Tg= 48.5 � 2.5 �C which is independent of side-chain and backbone DP. The mixing of bottlebrush polymers with linear chains was investigated by DSC. PNb(PLA58)50 and PNb(PLA57)200 were blended with NbPLA10 and NbPLA58 at various weight percent. PNb(PLA58)50 additives increased the Tg for the shorter NbPLA10 and decreased the Tg for the longer NbPLA58. Tg for NbPLA58 showed a more significant decrease when backbone DP of the bottlebrush polymer additive increased from 50 to 200. Figure 1. <img src='https://acs-archive-assets2.s3.amazonaws.com/240nm/uploads/45701_figure_1.jpg' alt='' />

Thermal properties of poly(lactic acid) bottlebrush polymer blends

247th National Meeting (2014)

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