Centimeter-scale giant spherulites in mixtures of polar polymers and crystallizable diluents: Morphology, structure, formation and application

Abstract

A series of giant spherulites at centimetre scale were effectively constructed from the mixtures of polyacrylonitrile (PAN)/dimethyl sulfone (DMSO2), although neither PAN nor DMSO2 itself forms spherical morphology during crystallization. A detailed investigation was carried out on the morphology, microstructure, and formation mechanism by polarized optical microscopy, scanning electron microscopy, wide-angle X-ray diffraction, polarized FTIR spectroscopy, and differential scanning calorimetry. These giant spherulites constituted of PAN phase and DMSO2 crystals alternately distributed in divergent patterns. The fast crystallization of DMSO2 dominates the large growth rate and the macroscopic size, while PAN composes the skeleton of the giant spherulites. The cooperative deposition of PAN beside DMSO2 crystals originates from dipole-dipole interaction between the nitrile groups of PAN and the sulfone groups of DMSO2, accounting for the branching and splaying in the giant spherulites. These macroscopic morphologies were universally observed in other mixtures of PAN/dimethyl sulfoxide, PAN/ maleic anhydride, poly(vinylidene fluoride)/DMSO2, and cellulose acetate/DMSO2. We propose that the giant spherulites can be formed by introducing suitable diluent crystallization and appropriate polymerdiluent interaction. Furthermore, this spherulitic pattern has been used as a template to direct the oriented growth of calcium carbonate based on the molecular orientation in the giant spherulite.

Polymorphism in the Assembly of Phase-Segregated Block Molecules: Pathway Control to 1D and 2D Nanostructures

“…Interestingly, the hydz-Si 16 -hydz, hydz-Si 24 -hydz, and hydz-Si 15 block molecules grow spherulites with sizes up to 5 mm from one nucleation point (Figure 1F). This has been reported occasionally for mixtures of polymers and small molecules, 47,48 but for oligomers with covalently attached small molecule end-groups, such large textures have not been reported to date. The nucleation point for spherulite growth appeared on millisecond time scales, which gives a first hint that a very fast thermal phase transition occurs in these systems.…”

Thermo-Sensitive Poly(p-dioxanone) Banded Spherulites with Controllable Patterns for Iridescence

“…These periodic ring textures can be controlled from 600 nm to >15 mm, 29,77,78 and some polymeric spherulites can grow up to 4 cm in dimensions. 79 Thus, these RBSs can serve as template substrates for replicate-manufacturing wrinkled textures with custom-made patterns. Tuning the height profile with an optimal inter-band space can produce desired photonic reflection from the RBS crystallized and cast as thin films.…”

“…Height profiles of the RBS top surface may differ with respect to annealing, crystallization temperature, etc. These periodic ring textures can be controlled from 600 nm to >15 mm, ,, and some polymeric spherulites can grow up to 4 cm in dimensions . Thus, these RBSs can serve as template substrates for replicate-manufacturing wrinkled textures with custom-made patterns.…”

ECTFE porous membranes with conveniently controlled microstructures for vacuum membrane distillation

“…2,4 ECTFE is insoluble in all known solvents at room temperature; 5 the fabrication of ECTFE membranes is not feasible via conventional methods such as the solution phase inversion method. However, since ECTFE is soluble in selected solvents at elevated temperatures, it is possible to fabricate membranes via the thermally induced phase separation (TIPS) process, which is a useful technique for the preparation of polymeric membranes and has been applied to many polymers, such as PP, [6][7][8] PE, 9,10 PAN 11,12 and PVDF. [13][14][15][16] A few studies have been reported on the preparation of ECTFE microporous membranes via TIPS.…”