Thiounn Timmy, Lauer Moira K, Bedford Monte S, Smith Rhett C, Tennyson Andrew G
Department of Chemistry and Center for Optical Materials Science and Engineering Technologies (COMSET), Clemson University Clemson South Carolina 29634 USA
Department of Materials Science and Engineering, Clemson University Clemson South Carolina 29634 USA.
RSC Adv. 2018 Nov 20;8(68):39074-39082. doi: 10.1039/c8ra06847j. eCollection 2018 Nov 16.
Network polymers of sulfur and poly(4-allyloxystyrene), PAOS ( = percent by mass sulfur, where is varied from 10-99), were prepared by reaction between poly(4-allyloxystyrene) with thermal homolytic ring-opened S 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 nor a from -50 to 140 °C, whereas higher sulfur content materials featured or values that scale with the amount of sulfur. DSC data also revealed that sulfur-rich domains of PAOS are comprised of sulfur-crosslinked organic polymers and amorphous sulfur, whereas, sulfur-rich domains in PAOS are comprised largely of α-sulfur (orthorhombic sulfur). These conclusions are further corroborated by CS-extraction and analysis of extractable/non-extractable fractions. Calculations based on TGA, FT-IR, HS trapping experiments, CS-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 PAOS and PAOS (on the order of 3 and 6 GPa at -37 °C, respectively), with a mechanical between -17 °C and 5 °C. A PAOS sample retains its full initial mechanical strength after at least 12 pulverization-thermal healing cycles, making it a candidate for facile repair and recyclability.
通过聚（4-烯丙氧基苯乙烯）与热均裂开环的硫在硫醇-烯型反应中反应，制备了硫与聚（4-烯丙氧基苯乙烯）（PAOS，硫的质量百分比，其中 从10%变化到99%）的网络聚合物。评估了硫含量和交联对热/机械性能的影响程度。发现硫含量低于50%的网络材料是热固性材料，而硫含量大于90%的材料是可热修复和可再熔化的。差示扫描量热法（DSC）分析表明，低硫含量材料在-50至140°C范围内既没有 也没有 ，而较高硫含量材料具有与硫含量成比例的 或 值。DSC数据还表明，PAOS的富硫区域由硫交联的有机聚合物和无定形硫组成，而PAOS中的富硫区域主要由α-硫（正交硫）组成。这些结论通过CS萃取和可萃取/不可萃取部分的分析得到进一步证实。基于热重分析（TGA）、傅里叶变换红外光谱（FT-IR）、HS捕集实验、CS可萃取质量和元素燃烧微分析数据的计算，用于评估游离硫和交联硫的相对百分比以及每个交联点的S原子平均数。动态力学分析表明，PAOS和PAOS具有较高的储能模量（分别在-37°C时约为3和6 GPa），在-17°C至5°C之间有一个力学 。一个PAOS样品在至少12次粉碎-热修复循环后仍保留其全部初始机械强度，使其成为易于修复和可回收利用的候选材料。
