Are RAFT and ATRP Universally Interchangeable Polymerization Methods in Network Formation?
Are RAFT and ATRP Universally Interchangeable Polymerization Methods in Network Formation?
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DOI：
10.1021/acs.macromol.1c01587
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发表时间：
2021-09-16
期刊：
影响因子：
5.5
通讯作者：
Konkolewicz, Dominik
中科院分区：
文献类型：
--
作者：
Cuthbert, Julia;Wanasinghe, Shiwanka, V;Konkolewicz, Dominik
用ATRP和RAFT两种方法合成了聚合物网络，以评价可逆失活自由基聚合方法的选择是否在分子或本体性质水平上影响材料的特性。由于ATRP中的控制是通过小分子催化剂与聚合物链端的相互作用获得的，而不是两个聚合物链端之间的简并转移，因此ATRP可以导致更好的网络控制，特别是在凝胶之后。总体而言，RAFT和ATRP都比相应的FRP工艺提供了更好的材料控制。总体而言，RAFT的凝胶分数越高，转化率越高。分子性质表明，在100或200个单位的较低目标链长处，对初级聚合物链长和初级链的分散性的控制方面的差异相对较小。然而，ATRP在500个基团的较长初级链长上提供了更好的控制聚合物。RAFT和ATRP网络都比它们的传统自由基类似物膨胀得更大，ATRP在较长的初级链长和较低的交联度时提供了略高的溶胀率。流变学分析表明，两种材料相似，但RAFT得到的材料具有较高的弹性模量，这与RAFT较高的转化率和较低的溶胶率相一致。总体而言，RAFT和ATRP形成的材料在较低的链长时具有相似的性能，而ATRP似乎在较长的链长时产生略好的性能。RAFT和ATRP中的控制可能是通过可溶性成分实现的，包括ATRP中的小分子催化剂和RAFT中的可溶性聚合物组分(Sol)。
Polymer networks were synthesized by both ATRP and RAFT to evaluate whether the choice of reversible deactivation radical polymerization method impacted the materials' characteristics at either the molecular or bulk property level. Since control in ATRP is gained through interactions of a small-molecule catalyst with the polymer chain end, rather than degenerative transfer between two polymer chain ends, ATRP could lead to better controlled networks, particularly after gelation. In general, both RAFT and ATRP gave better controlled materials than the corresponding FRP processes. In general, RAFT reached higher conversions with higher gel fractions. The molecular properties indicate relatively small differences in control over the primary polymer chain length and the dispersity of the primary chains at lower targeted chain lengths of 100 or 200 units. However, ATRP provided better controlled polymers at longer primary chain lengths of 500 units. Both RAFT and ATRP networks swelled to greater extents than their conventional radical analogs, with ATRP giving somewhat higher swelling ratios at longer primary chain lengths and lower crosslink densities. Rheological analysis indicates that both materials are similar, although RAFT gave materials with higher elastic moduli, consistent with the higher conversion and lower sol fraction in RAFT. Overall, both RAFT and ATRP formed materials with similar properties at lower chain lengths, with ATRP appearing to yield slightly better properties at longer chain lengths. The control in RAFT and ATRP is likely through soluble components, including the small-molecule catalyst in ATRP and soluble polymer fractions (sol) in RAFT.