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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 29, Number 6
BKCSDE 29(6)
June 20, 2008 

Glass Transition Behavior of Dendritic Polymers Containing Mobile Aliphatic Polyether Cores and Glassy Peripheral Polystyrenes
Jie Song, Byoung-Ki Cho*
Dendrons, Polystyrene, Glass transition temperature
We investigated the glass transition temperatures (Tg) of dendrons consisting of conformationally mobile aliphatic polyether dendritic cores plus glassy peripheral polystyrenes (PSs), and linear PSs in the molecular weight range of 1000-8500 g/mol. We compared their Tg behavior depending on their polymeric architecture. The linear PSs show a typical growth of Tg up to 92.5 oC as the molecular weight increases to 8300 g/mol, while the dendrons display nearly constant Tg values of 58-61 oC, despite the increase of molecular weight with each generation. The striking contrast of Tg behavior would be mainly attributed to the fact that the dendrons keep the ratio of Ne/M (Ne: number of peripheral chain ends, M: molecular weight) over all the generations. Additionally, for the influence of dendritic spacers on glass transition temperature we prepared dimeric PSs with different linkage groups such as aliphatic ether, ester and amide bonds. We found that the dimer with the ether spacer exhibited the lowest glass transition at 55.4 ℃, while the amide linked dimer showed the highest glass transition temperature at 74.2 ℃. This indicates that the peripheral PS chains are effectively decoupled by the conformationally flexible ether spacer. The results from this study demonstrated that polymeric architecture and dendritic core structures play a crucial role in the determination of glass transition behavior, providing a strategy for the systematic engineering of polymer chain mobility.
1167 - 1172
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