Diverse morphological formations and lamellar dimensions of poly(ε-caprolactone) crystals in the monolayers grafted onto solid substrates

Publication date: Available online 30 January 2017
Source:Polymer
Author(s): Takayuki Ikehara, Toshiyuki Kataoka
Poly(ε-caprolactone) (PCL) chains grafted onto Si substrates, namely PCL brushes, exhibited diverse structures such as dendrites, branched linear crystals, and curved crystals with dendrites when they were isothermally crystallized from melts. The crystallization was possible over a wide range of temperature. The discussion on the lamellar thickness of the dendrites indicated that the equilibrium melting point, Tm^°, in a grafted layer was higher than the values reported for bulk-crystallized PCL and that the surface free energy of the fold surfaces of lamellae was within the range reported so for. The value of Tm^° implied that the conformational entropy is reduced in the grafted layers than in bulk. The grafted layers were prepared using a novel "grafting-to" method, where the middle parts of the polymer molecules, instead of the chain ends, are reacted to silanized Si substrates.

Graphical abstract

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