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Transparent and toughening epoxy thermosets modified by linear telechelic polymer containing rigid spiroacetal moieties: Uncovering the relationship between the heterogeneous crosslinked network and thermoset performances
Author(s) -
Zheng Yaochen,
Song Peng,
Liu Shaoxiang,
Wu Mengqing,
Xu Hui,
Qiao Chenghui,
Liu Jian,
Gao Zhengguo,
Ban Qingfu
Publication year - 2021
Publication title -
journal of polymer science
Language(s) - English
Resource type - Journals
eISSN - 2642-4169
pISSN - 2642-4150
DOI - 10.1002/pol.20210178
Subject(s) - thermosetting polymer , epoxy , materials science , small angle x ray scattering , composite material , polymer , polymer chemistry , telechelic polymer , copolymer , end group , scattering , physics , optics
Abstract Spiroacetal moieties containing linear telechelic polymers (LTPs) with two terminal epoxy groups were facilely synthesized via the successive thiol‐ene and thiol‐epoxy click additions. The LTPs were incorporated into epoxy matrix to fabricate the transparent and toughening thermosets. In term of the miscibility of epoxy with the adduct of ethanedithiol and 3,9‐divinyl‐2,4,8,10‐tetraoxaspiro[5.5]undecane (BTU), it is proposed that the size of the formed nanostructures was small enough to allow light penetrate. Therefore, the modified thermosets were transparent, which was further confirmed by small‐angle X‐ray scattering (SAXS) measurements. The LTPs with an alternating structure of rigid spiroacetal moiety and soft thioether could formed heterogeneous crosslinked networks (HCNs) and obviously toughen epoxy thermosets. Flexural strength increased from 1.06 GPa for neat epoxy to 2.09 GPa for toughening thermosets modified with 15 wt% LTPs. The stress field intensity ( K IC ) value reached up to 3.93 by more than 125% compared with that of the control sample (1.75). This work uncovered the role of HCNs on performance and paved a way for technological advances toward transparent and toughening materials in epoxy thermosets.