Abstract
The growth of lamellar crystals has been studied in particular for spherulites in polymeric materials. Even though such spherulitic structures and their growth are of crucial importance for the mechanical and optical properties of the resulting polymeric materials, several issues regarding the residual stress remain unresolved in the wider context of crystal growth. To gain further insight into micro-mechanical forces during the crystallization process of lamellar crystals in polymeric materials, herein, we introduce tetraarylsuccinonitrile (TASN), which generates relatively stable radicals with yellow fluorescence upon homolytic cleavage at the central C–C bond in response to mechanical stress, into crystalline polymers. The obtained crystalline polymers with TASN at the center of the polymer chain allow not only to visualize the stress arising from micro-mechanical forces during polymer crystallization via fluorescence microscopy but also to evaluate the micro-mechanical forces upon growing polymer lamellar crystals by electron paramagnetic resonance, which is able to detect the radicals generated during polymer crystallization.
Highlights
The growth of lamellar crystals has been studied in particular for spherulites in polymeric materials
As TASN at the cross-linking point can be cleaved in response to the solventcoagulation force in freezing cross-linked polymer gels, we hypothesized that TASN in a tie molecule could potentially be mechanically cleaved by the growth of lamellar crystals (: crystallization-induced mechanofluorescence (CIMF)) (Fig. 1b)
Radical-type mechanofluorophores such as tetraarylsuccinonitrile (TASN) allow us to evaluate the micro-mechanical forces during polymer crystallization in crystalline polymers by electron paramagnetic resonance (EPR) spectroscopy and to visualize it by fluorescence microscopy
Summary
The growth of lamellar crystals has been studied in particular for spherulites in polymeric materials. To gain further insight into micro-mechanical forces during the crystallization process of lamellar crystals in polymeric materials, we introduce tetraarylsuccinonitrile (TASN), which generates relatively stable radicals with yellow fluorescence upon homolytic cleavage at the central C–C bond in response to mechanical stress, into crystalline polymers. The obtained crystalline polymers with TASN at the center of the polymer chain allow to visualize the stress arising from micro-mechanical forces during polymer crystallization via fluorescence microscopy and to evaluate the micro-mechanical forces upon growing polymer lamellar crystals by electron paramagnetic resonance, which is able to detect the radicals generated during polymer crystallization Crystalline polymers such as polyethylene and polyethylene terephthalate are indispensable for our daily lives. Fluorescence microscopy observations of CIMF allows the precise identification of the stress location and an in-depth clarification of the polymer crystallization process
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