Solution‐grown crystals of poly(vinylidene fluoride)

Single crystals of poly(vinylidene fluoride)

“…Sakaoku and Peterlin6 obtained nearly hexagonal lamellae of the a polymorph from a 0.05% solution of PVFB in a boiling acetone/xylene mixture (1:l) slowly cooled. The procedures of Okuda et al 5 were followed by Hasegawa, Kobayshi, and Tadokoro7 to prepare samples for x-ray diffraction studies leading to the results shown in Table I. We report here, then, what appears to be the first successful preparation of single crystals of PVFZ in a form other than the a polymorph. Figure 1 shows an essentially hexagonal lamella obtained from a 0.02% solution of PVF2 in boiling cyclohexanone crystallized at 80OC.…”

The structure and properties of block poly(vinylidene fluoride) and systems based on it

“…35 The presence of the a phase on crystallisation from solution in cyclohexanone (on the surface of water) has been confirmed indirectly by the presence of spherulites in the crystallised films 41 which are usually produced by crystals of this modification. The conclusion that the y phase is formed on crystallisation from a mixture of good and poor solvents for PVDF 39 has been confirmed by the results of a study 42 where monochlorobenzene was again used as the poor solvent, whilst the good solvent was dimethylacetamide. According to this study, 39 the y phase crystallises at a concentration of 0.1%, whereas at a concentration of 0.5% the a modification is actually produced.…”

“…The conclusion that the y phase is formed on crystallisation from a mixture of good and poor solvents for PVDF 39 has been confirmed by the results of a study 42 where monochlorobenzene was again used as the poor solvent, whilst the good solvent was dimethylacetamide. According to this study, 39 the y phase crystallises at a concentration of 0.1%, whereas at a concentration of 0.5% the a modification is actually produced. It has been noted that the crystals of the y phase are very resistant to an electron beam, i.e.…”

“…According to this may be the cause of the assignment of the y phase to the orthorhombic system with the Clan space group, on the one hand, and to the monoclinic system with the Cc space group, on the other. Tables 2-4 An attempt has been made 39 to obtain PVDF single crystals by crystallisation from solution. A 90:10 mixture of monochlorobenzene and dimethylformamide was used as the solvent.…”

The polymorphism of poly(vinylidene fluoride). II. The effect of hydrostatic pressure

“…The electron-diffraction patterns of these lamellar crystals yielded no 001 reflections. Thus the c-axis was perpendicular to the plane of the crystals [16,17]. Analysis of small-angle X-ray data from films of PVF, phase 11 results in a long-period spacing of 1 5 0 i .…”