Block Copolymer Self-Assembly Induced Compatibilization of PCL/PS−PEP Blends

Abstract

An interesting way to obtain compatible blends of poly(ε-caprolactone) (PCL) and polystyrene-b-poly(ethylenepropylene) (PS−PEP) has been achieved. The intrinsically immiscible blends such as PCL/PS and PCL/PEP become compatible while the PS and PEP components form a diblock copolymer to melt blending with PCL. The morphology of PCL/PS−PEP blends was examined by polarized light microscopy, small-angle X-ray scattering, and transmission electron microscopy (TEM). The PCL/PS−PEP blends were found to self-assemble as lamellar microstructure with tens of nanometers dimension. Their compatibilities were investigated in terms of differential scanning calorimetry. No significant change on the T g of PEP-rich phase in the blends has been found whereas the T g of PS-rich phase gradually decreases with decreasing the molecular weight of PCL in blends. However, the changes on the T g of PS are insignificant as compared to the expected glass transition temperature predicted by the Fox equation. Taking advantage of the driving force of self-assembly for block copolymers, the PCL component appears to be localized in between the lamellar microdomains of PS block. The behavior of localization for PCL was further confirmed by the TEM phase contrast imaging. Contrary to typical microphase-separated morphology of crystallizable block copolymers (designated as chemically confined environment for crystallizing blocks), we name this unique phase-separated morphology as a physically confined environment for the crystallization of PCL.

Morphology of poly(styrene‐block‐dimethylsiloxane) copolymer films

“…In general, the morphologies of thin copolymer films can be tuned by the molecular weight and composition of the diblock copolymer, the surface-block interactions, and the film thickness. 5,6 A large number of studies have been reported on thermally equilibrated thin films of diblock and triblock copolymers, and they have revealed a rich variety of rather complex morphologies. Layers of microdomains, cylinders, or spheres oriented parallel to the interface in asymmetric block copolymer films have been reported.…”

Compatibilization of Immiscible Poly(propylene)/Polystyrene Blends Using Clay

“…[1,2] Usually, the interfacial interactions are enhanced by (i) use of a functionalized modifier, and (ii) addition or in-situ formation of a block (graft) copolymer, the blocks of which have the same or similar chemical composition as the homopolymers in their immiscible blend. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] A compatibilizer can reduce particle sizes by lowering the interfacial tension, preventing particles from coalescing, and promoting adhesion between the two homopolymer phases, which results in improved mechanical properties.…”

Functional copolymer/organo-MMT nanoarchitectures. XIX. Nanofabrication and characterization of poly(MA-alt -1-octadecene)-g -PLA layered silicate nanocomposites with nanoporous core-shell morphology

“…Moreover, TEM method allows a qualitative understanding of the internal structure, spatial distribution of the various phases and direct visualization of defect structure in the nanocomposites. The self‐assembly of functional block and random copolymers with hydrophobic and hydrophilic units to enable micro phase separation has been intensively investigated due to their ability to form nanostructures like micelles, vesicles and capsules . However, the association of alternating copolymers/organoclay nanosystems, especially the formation of self‐assembled core–shell morphology in similar systems, has scarcely been studied.…”