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Title: Thermally-healable network solids of sulfur-crosslinked poly(4-allyloxystyrene)
Network polymers of sulfur and poly(4-allyloxystyrene), PAOSx ( x = percent by mass sulfur, where x is varied from 10–99), were prepared by reaction between poly(4-allyloxystyrene) with thermal homolytic ring-opened S 8 in a thiol-ene-type reaction. The extent to which sulfur content and crosslinking influence thermal/mechanical properties was assessed. Network materials having sulfur content below 50% were found to be thermosets, whereas those having >90% sulfur content are thermally healable and remeltable. DSC analysis revealed that low sulfur-content materials exhibited neither a T g nor a T m from −50 to 140 °C, whereas higher sulfur content materials featured T g or T m values that scale with the amount of sulfur. DSC data also revealed that sulfur-rich domains of PAOS90 are comprised of sulfur-crosslinked organic polymers and amorphous sulfur, whereas, sulfur-rich domains in PAOS99 are comprised largely of α-sulfur (orthorhombic sulfur). These conclusions are further corroborated by CS 2 -extraction and analysis of extractable/non-extractable fractions. Calculations based on TGA, FT-IR, H 2 S trapping experiments, CS 2 -extractable mass, and elemental combustion microanalysis data were used to assess the relative percentages of free and crosslinked sulfur and average number of S atoms per crosslink. Dynamic mechanical analyses indicate high storage moduli for PAOS90 and PAOS99 (on the order of 3 and 6 GPa at −37 °C, respectively), with a mechanical T g between −17 °C and 5 °C. A PAOS99 sample retains its full initial mechanical strength after at least 12 pulverization-thermal healing cycles, making it a candidate for facile repair and recyclability.  more » « less
Award ID(s):
1708844
PAR ID:
10097960
Author(s) / Creator(s):
; ; ; ;
Date Published:
Journal Name:
RSC Advances
Volume:
8
Issue:
68
ISSN:
2046-2069
Page Range / eLocation ID:
39074 to 39082
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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