ABA üç bloklu kopolimerlerin halka açılım polimerizasyonu ile sentezlenmesi ve yapı-özellik davranışlarının incelenmesi

Poly(?-caprolactone)?polydimethylsiloxane?poly(?-caprolactone) (PCL-PDMS-PCL) and poly(?-caprolactone)-poly(ethylene oxide)-poly(?-caprolactone) (PCL-PEO-PCL) triblock copolymers having a wide range of mid-block and end-block lengths (1000 ? 32000 g/mol) were synthesized by the ring-opening polymerization of caprolactone using functionally terminated PDMS and PEO oligomers.Effect of the polymer composition and the average lengths of the mid and end blocks on;(i)extent of microphase separation and polymer morphology,(ii)crystallization of PCL segments(iii)thermal properties of copolymers and(iv)surface properties of the polymers, were investigated.Materials were characterized by FTIR spectroscopy, gel permeation chromatography (GPC), atomic force microscopy (AFM), temperature-dependent optical microscopy (OM), X-Ray Diffraction analyses (XRD), differential scanning calorimetry (DSC) and static water contact angle measurements. PCL-PDMS-PCL copolymers displayed well microphase separated morphologies. The extent of microphase separation was strongly dependent on the lengths of both PCL and PDMS segments. It was seen that the hydrophobicity of the copolymer surfaces was enhanced with increasing PDMS molecular weight. Crystallization of PCL blocks was affected by the amount and the molecular weight of the PDMS mid-block as revealed by DSC, OM and XRD analyses. PCL-PEO-PCL copolymers exhibited competitive crystallization due to presence of two crystallizable segments within the same copolymer. DSC analysis showed the presence of different crystal structures which were reflected as multiple melting peaks in the thermograms. PCL end-blocks overwhelmed the crystallization of PEO mid-block and the extent of suppression of PEO crystallization increased with increasing PCL fraction as determined by XRD and OM.