Alabiso Walter, Sölle Bernhard, Reisinger David, Guedes de la Cruz Gema, Schmallegger Max, Griesser Thomas, Rossegger Elisabeth, Schlögl Sandra
Polymer Competence Center Leoben GmbH, Sauraugasse 1, A-8700, Leoben, Austria.
Chair of Chemistry of Polymeric Materials, Montanuniversitaet Leoben, Otto-Glöckel-Straße 2, A-8700, Leoben, Austria.
Angew Chem Int Ed Engl. 2023 Nov 6;62(45):e202311341. doi: 10.1002/anie.202311341. Epub 2023 Sep 27.
Chemical amplification is a well-established concept in photoresist technology, wherein one photochemical event leads to a cascade of follow-up reactions that facilitate a controlled change in the solubility of a polymer. Herein, we transfer this concept to dynamic polymer networks to liberate both catalyst and functional groups required for bond exchange reactions under UV irradiation. For this, we exploit a photochemically generated acid to catalyse a deprotection reaction of an acid-labile tert-butoxycarbonyl group, which is employed to mask the hydroxy groups of a vinyl monomer. At the same time, the released acid serves as a catalyst for thermo-activated transesterifications between the deprotected hydroxy and ester moieties. Introduced in an orthogonally cured (450 nm) thiol-click photopolymer, this approach allows for a spatio-temporally controlled activation of bond exchange reactions, which is crucial in light of the creep resistance versus reflow ability trade-off of dynamic polymer networks.
化学放大是光刻胶技术中一个成熟的概念，其中一个光化学事件会引发一系列后续反应，从而有助于聚合物溶解度的可控变化。在此，我们将这一概念应用于动态聚合物网络，以在紫外线照射下释放键交换反应所需的催化剂和官能团。为此，我们利用光化学产生的酸来催化酸不稳定的叔丁氧羰基的脱保护反应，该基团用于保护乙烯基单体的羟基。同时，释放出的酸作为催化剂，促进脱保护羟基与酯部分之间的热活化酯交换反应。将这种方法引入正交固化（450 nm）的硫醇点击光聚合物中，可实现键交换反应的时空可控活化，这对于动态聚合物网络的抗蠕变性与回流能力之间的权衡至关重要。
