Formation of porous microspheres from semicrystalline polymer solutions: diffusion-controlled and local phase separation

ABSTRACT

The work represents a study of structure formation during thermally induced phase separation in low concentrated blends of semicrystalline polymers with thermodynamically poor solvents. According to the phase diagram, cooling of homogeneous blends located to the left of the upper critical solution temperature can cause two phase separation scenarios. The fact that both scenarios are possible is experimentally confirmed by investigating blends of polypropylene with a cosolvent and polyamide-12 with a cosolvent, using polarized light optical microscopy and scanning electron microscopy. The study proves the possibility to develop facile approaches to the formation of porous microspheres from semicrystalline polymers.

Graphical Abstract

KEYWORDS:

• Semicrystalline polymer
• thermally induced phase separation
• porous microsphere
• phase diagram
• hot-stage microscopy

Acknowledgments

The authors are grateful for the possibility to use the equipment of the Upper Volga Region Center of Physico-Chemical Research. The study was carried out as a part of the ISC RAS State Program.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes

1. The numbers in brackets indicate the numbers of the areas circled by dashed lines in Figure 3, where the discussed events take place.

Additional information

Notes on contributors

Konstantin Vasilyevich Pochivalov

Konstantin Vasilyevich Pochivalov is a senior researcher at G.A. Krestov Institute of Solution Chemistry, Russian Academy of Sciences. He was conferred his PhD in polymer science in 1989 and Doctor of Chemistry degree in 2002. His current research interests are thermodynamics and phase structure of semicrystalline polymer blends with low molecular liquid and crystalline substances; investigation of behavior of such blends by differential scanning calorimetry and X-ray diffraction; phase diagrams; effect of semicrystalline polymers swelling on their crystalline structure; development of membrane formation techniques via thermally induced phase separation and nonsolvent-induced phase separation. He is the author of more than 50 research articles and 8 patents.

Andrey Viktorovich Basko

Andrey Viktorovich Basko was conferrred his PhD degree in polymer science in 2020. He is a researcher at G.A. Krestov Institute of Solution Chemistry, Russian Academy of Sciences. In recent years he has focused on understanding of the mechanism of structure formation of porous materials from semicrystalline polymer mixtures with low molecular weight substances by means of polarized light hot stage microscopy, scanning electron microscopy and differential scanning calorimetry and construction of phase diagrams for the above mixtures.