Preirradiation Graft Polymerization of Styrene in a Poly(tetrafluoroethylene) Film Investigated by Time-Resolved Small-Angle Neutron Scattering

Hiroki Iwase,Satoshi Koizumi,Shin-Ichi Sawada,Yasunari Maekawa,Tetsuya Yamaki

doi:10.1155/2011/301807

Hiroki Iwase, Satoshi Koizumi + Show 3 more

Open Access

https://doi.org/10.1155/2011/301807

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Abstract

Preirradiation graft polymerization of styrene in a poly(tetrafluoroethylene) (PTFE) film was examined by time-resolved small-angle neutron scattering (SANS). A crosslinked PTFE film, thickness of which is about 50 μm, was irradiated byγ-ray and immersed in a mixed solvent of styrene monomer and toluene. SANS elucidated that graft polymerization proceeds by two reaction processes (I) and (II). In process (I) at min, graft polymerization occurs at an interface between crystalline and amorphous PTFE domains and the grafted polystyrene segregates from PTFE, forming a thin layer with a sharp interface. In process (II) at min, grafted PS layer starts to bridge between crystalline domains. At the end of process (II), 40% of total crystalline PTFE domain is covered by the grafted PS chains.

Highlights

Preirradiation polymerization, using ionizing radiation, was intensively explored in the middle of twentieth century [1]
We found that Preirradiation process of step (2) proceeds by two steps: process I of thin layer formation by grafted PS chains surrounding a PTFE crystalline domain and process interface. In process (II) of network formation among PTFE crystalline domains
We investigated Preirradiation graft polymerization of styrene in a crosslinked poly(tetrafluoroethylene) (c-PTFE) film by time-resolved smallangle neutron scattering (SANS)

Summary

Introduction

Preirradiation polymerization, using ionizing radiation, was intensively explored in the middle of twentieth century [1]. When a PTFE film is irradiated by ionizing radiation (step (2) in Figure 1(a)) and immersed in styrene (St) monomers, the film starts to be swollen by St monomers and graft polymerization occurs homogeneously throughout a whole film This radical polymerization continues to be living for hours, days, or sometimes months. Graft polymerization starts to occur at the interface between crystalline and amorphous domains This scenario, describing Preirradiation polymerization in a crystalline film, involves interdisciplinary scientific topics, such as (i) production, stabilization, and diffusion of free radicals in a crystalline PTFE domain, (ii) radical polymerization, (iii) phase separation between PTFE and PS chains, and (iv) deformation and breakage of a film by swelling monomer or grafted polymers. We found that Preirradiation process of step (2) proceeds by two steps: process I of thin layer formation by grafted PS chains surrounding a PTFE crystalline domain and process II of network formation among PTFE crystalline domains

Experimental

Experimental Results and Discussions

Small-Angle Neutron Scattering

Conclusion