Donor modification of thermally activated delayed fluorescence photosensitizers for organocatalyzed atom transfer radical polymerization,Polymer Chemistry

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Donor modification of thermally activated delayed fluorescence photosensitizers for organocatalyzed atom transfer radical polymerization
Polymer Chemistry ( IF 4.1 ) Pub Date : 2022-06-24 , DOI: 10.1039/d2py00470d
Alexander M. Polgar ₁ , Shine H. Huang ₁ , Zachary M. Hudson ₁

Affiliation

Thermally activated delayed fluorescence (TADF) photosensitizers based on 9,10-dihydro-9,9-dimethylacridine/2,4,6-triphenylpyrimidine conjugates with strong visible absorption, large excited state reduction potentials, and long-lived triplet excited states were successfully employed in the organocatalyzed atom transfer radical polymerization (O-ATRP) of methacrylic monomers. A donor-modification strategy dramatically improved the stability of the photocatalyst radical cations, while retaining their high oxidizing strengths, a key requirement for controlled O-ATRP. Time-resolved photoluminescence studies of the catalysts support initiation by electron transfer from both singlet and triplet states, with functionalized donors producing higher driving forces for photoinduced electron transfer. A donor-modified TADF photocatalyst was found for the synthesis of methacrylic polymers with Đ below 1.3 at catalyst loadings down to 50 ppm. This catalyst was also successfully applied in block copolymer synthesis, while the unfunctionalized analogue yields entirely uncontrolled polymerization.

中文翻译：

用于有机催化原子转移自由基聚合的热活化延迟荧光光敏剂的供体改性

基于具有强可见光吸收、大激发态还原电位和长寿命三重激发态的 9,10-二氢-9,9-二甲基吖啶/2,4,6-三苯基嘧啶缀合物的热激活延迟荧光 (TADF) 光敏剂成功用于甲基丙烯酸单体的有机催化原子转移自由基聚合（O-ATRP）。供体改性策略显着提高了光催化剂自由基阳离子的稳定性，同时保持其高氧化强度，这是受控 O-ATRP 的关键要求。催化剂的时间分辨光致发光研究支持从单重态和三重态的电子转移引发，官能化供体产生更高的光诱导电子转移驱动力。Đ在催化剂负载量低至 50 ppm 时低于 1.3。这种催化剂也成功地应用于嵌段共聚物的合成，而未官能化的类似物则产生完全不受控制的聚合。

更新日期：2022-06-24

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