SANS study on the nano-crystalline network structure of elastic physical gels made of syndiotactic polypropylene

Fuyuaki Endo; Naruki Kurokawa; Keishi Tanimoto; Hiroki Iwase; Tomoki Maeda; Atsushi Hotta

doi:10.1039/c9sm00582j

SANS study on the nano-crystalline network structure of elastic physical gels made of syndiotactic polypropylene

Soft Matter. 2019 Jul 10;15(27):5521-5528. doi: 10.1039/c9sm00582j.

Authors

Fuyuaki Endo¹, Naruki Kurokawa¹, Keishi Tanimoto¹, Hiroki Iwase², Tomoki Maeda¹, Atsushi Hotta¹

Affiliations

¹ Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan. hotta@mech.keio.ac.jp.
² Research Center for Neutron Science and Technology, Comprehensive Research Organization for Science and Society (CROSS), 162-1 Shirakata, Tokai, Ibaraki 319-1106, Japan.

PMID: 31241635
DOI: 10.1039/c9sm00582j

Abstract

The structure-property relationship of an elastic physical gel, obtained by simply quenching syndiotactic polypropylene (sPP)/decahydronaphthalene solution with liquid nitrogen, was investigated based on small-angle neutron scattering (SANS) analysis. The SANS analysis revealed that sPP nanocrystals with a constant radius of 4-5 nm existed in the sPP gels regardless of the sPP concentration, whereas the correlation length of the nanocrystals drastically decreased from ∼130 to ∼20 nm upon increasing the sPP concentration from 2 to 12 wt%. The volume fraction and the number density of the sPP nanocrystals increased monotonously with the increase in the sPP concentration. The rheological properties and the melting behavior of the quenched sPP gels were highly consistent with the number density of the nanocrystals calculated from the SANS analysis, strongly suggesting that the sPP nanocrystals actually worked as crosslinking points by inducing elasticity in the quenched sPP gels.