Blends of amorphous-crystalline block copolymers with amorphous homopolymers. Morphological studies by electron microscopy and small angle scattering

Abstract

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Preferential orientation of crystallites spatially confined in lamellar microdomains of polyethylene-block-[atactic poly(propylene)]

“…The crystalline lamellae lay along the c-axis, and the caxis rotates around the b-axis, therefore, the scattering between the crystalline lamellae should be identical for all directions. It has already been shown in our previous SAXS experiment [9] that the Lorentz corrected scattering intensities from oriented and "frozen" DEP were identical for all directions. In the previous work, we interpreted the identical scattering for all directions as the random orientation of the crystallite, however, the interpretation should be corrected as mentioned in this section.…”

“…At the same time, they claimed the parallel orientation for PE-blockpoly(vinylcyclohexane). [7] On the other hand, we have shown in previous studies [8,9] of a series of PE-block-[atactic poly(propylene)] (DEP) samples that the PE crystallites orient randomly in the lamellar microdomain, which is not compatible with either the parallel or perpendicular orientation. Although all groups examined the same type of polyethylene, which was prepared through hydrogenation of an anionically polymerized polybutaCommunication: Synchrotron small angle X-ray scattering (SAXS), wide angle X-ray scattering (WAXS), and transmission electron microscopy were carried out for an oriented polyethylene-block-[atactic poly(propylene)] with a molecular weight of 1.13610 5 and a volume fraction of polyethylene of 0.5.…”

“…The DEP sample with this M -w is strongly segregated in the melt state and, therefore, forms a lamellar microdomain structure with a domain spacing (D) of 78 -83 nm. [8,9] The lamellar microdomain was oriented by applying a planar shear extension at about 150 8C (above the melting temperature of PE), and the sample was subsequently immersed in a mixture of isopropyl alcohol and dry ice (about -40 8C, below the glass transition temperature of atactic polypropyrene). [8] This procedure could "freeze" the morphology formed in the melt state and the sample maintained this structure while stored at room temperature.…”

Crystallization Behavior of PEO in Nano‐Structured PEO‐b‐PS/PPO Blends

“…Isothermal crystallization kinetics was obtained by monitoring the endothermal peaks. Samples were heated to an initial temperature of 1608C for 5 min and then cooled to 158C with a cooling rate of 108C min 21 , where they were crystallized for different time intervals (1,3,5,10,15,20,30,40,60, and 90 min, respectively). Subsequently, they were heated at 108C min 21 to the initial temperature, and the heats of fusion were obtained from the integration of the endothermal peaks.…”

Morphology and crystallization in mixtures of poly(methyl methacrylate)-poly(pentafluorostyrene)-poly(methyl methacrylate) triblock copolymer and poly(vinylidene fluoride)

“…Most studies have employed homopolymers with repeat units identical to one of the component blocks of the block copolymers. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] Only a few studies have considered mixtures where the homopolymer is different from either the block segments of the block copolymer, but is miscible with one of the component blocks. [20][21][22][23][24][25] In an attempt to investigate the effect of the addition of a semicrystalline homopolymer on the phase-separated morphology of a block copolymer in the mixtures, the present study prepares a series of binary mixtures of an fully-amorphous, symmetric triblock copolymer of poly(methyl methacrylate)-b-poly(pentafluorostyrene)-b-poly(methyl methacrylate) (denoted as PMMA-PPFS-PMMA) and a semicrystalline homopolymer of poly(vinylidene fluoride) (PVDF).…”