Crystallization in segregated supramolecular pseudoblock copolymers

Abstract

Crystallization in polymers under confinement can lead to strong effects, depending on the physical nature of the confining blocks. The present publication addresses crystallization in segregated supramolecular pseudoblock copolymers (SPBCPs, (PCL-Thy)-s-(PS-Tr)) where two constraints are present: one constraint is formed by a hydrogen bonding system connecting two microphase-segregating polymers, the second constraint is formed by the phase boundary of the segregating (PS)-polymer block. Thus mono-functionalized polymers bearing either a thymine end group or 2,4-diaminotriazine end group are prepared and blended together via the association of H-bonding interactions. Thymine functionalized crystallizable poly(ε-caprolactone) (PCL-Thy) and 2,4-diaminotriazine functionalized poly(styrene) (PS-Tr) with molecular weights ranging from 3000g/mol to 6000g/mol and 3000g/mol to 11,000g/mol respectively exhibit complete end group transformation as proven by NMR and MALDI methods. Crystallization studies via DSC experiments show a strong influence on the melting behavior of the PCL crystals upon attaching the PS block. Two distinct Tgs (DSC studies) corresponding to the respective polymers (PCL and PS) are shown for SPBCPs with higher PS block ratio, while ‘cold crystallization’ is shown for samples with nearly equal volume fraction of PCL and PS blocks. In-situ temperature dependent SAXS studies of the SPBCPs indicates a confinement effect of the PS-blocks on the crystallization of PCL, leading to an ordered arrangement of the PCL crystals.