Recent work has been lacking in studying the behaviors of copolymers with equal weight fractions, and the melting behavior of these copolymers may be related to their crystallization properties and behaviors. Equal weight fractions (5k5k, 8k8k, and 10k10k) of the block copolymer poly(ethylene oxide) -block -poly(caprolactone-ethylene glycol) (PEO-b-PCL) were dissolved in 2% w/w solutions of several different solvents: acetone, toluene, methyl ethyl ketone (MEK), and chloroform. The samples were then melted and analyzed using both differential scanning calorimetry (DSC) and Fourier transform- infrared spectroscopy (FT-IR), both at a rate of 2oC/min. The DSC was used to determine if the blocks had separate melting temperatures in each solvent or if they melted simultaneously. Analysis of the characteristic FT-IR peaks for each block (840 cm-1 for PEO and 735 cm-1 for PCL) determined the melting temperature for each block and whether the melting was simultaneous or not. The melting behavior in each solvent was compared to the general crystallization behavior in each solvent. PCL melted first in acetone and MEK while PEO and PCL melted simultaneously in toluene and chloroform. Further work involved heating the samples in the solvents that had separate melting temperatures (acetone and MEK) to the lower experimental melting temperature at a rate of 2oC/min in the FT-IR and held for 15 minutes at that temperature. The spectrum was then analyzed to see if the second block would melt after being held at that temperature, which determined whether the separate melting phases were time or temperature dependent.

Solvent effects of melting behavior of diblock copolymers of equal weight fractions

255th National Meeting (2018)

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