Phase Separation and pH-Dependent Behavior of Four-Arm Star-Shaped Porphyrin-PNIPAM4 Conjugates
Phase Separation and pH-Dependent Behavior of Four-Arm Star-Shaped Porphyrin-PNIPAM4 Conjugates
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四臂星形卟啉-PNIPAM4 缀合物的相分离和 pH 依赖性行为
DOI：
10.1021/acs.macromol.1c02188
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发表时间：
2022
期刊：
影响因子：
5.5
通讯作者：
Labuta Jan
中科院分区：
文献类型：
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作者：
Velychkivska Nadiia;Sedlacek Ondrej;Shatan Anastasiia B.;Spasovova Monika;Filippov Sergey K.;Chahal Mandeep K.;Janisova Larisa;Brus Jiri;Hanykova Lenka;Hill Jonathan P.;Winnik Francoise M.;Labuta Jan
采用可逆加成-断裂链转移聚合的方法合成了四臂连接到中心四苯基卟啉单元上的星形卟啉-PNIPAM4(PP)偶联物。研究了共轭化合物的温度诱导相分离行为，并利用Flory-Huggins理论绘制了低临界溶液温度(II类)-组成相图。有趣的是，与PNIPAM均聚物相比，PPP共轭化合物的PNIPAM臂较短导致了较低的相分离温度(Tp)。还确定了协作域大小的浓度依赖性。实验数据表明，在Tp以下，PP表现为长度依赖于浓度的一维超分子聚合物，而在Tp以上，PP球体呈较大的球形。在相分离和质子化之间观察到了各种温度-pH可逆和不可逆的相互依赖关系(“交叉效应”)。PP偶联物代表了具有多种聚集态的温度-pH-响应双重模型体系，使它们成为视觉指示剂、pH或温度传感器或生物医学应用的单线态氧发生器的候选对象。
Star-shaped porphyrin-PNIPAM4(PP) conjugates having four PNIPAM arms connected to a central tetraphenylporphyrin unit were synthesized using reversible addition–fragmentation chain-transfer polymerization. Temperature-induced phase-separation behavior of the conjugates was investigated, and the lower critical solution temperature (type II)–composition phase diagram was constructed using Flory–Huggins theory. Interestingly, in contrast to PNIPAM homopolymers, the shorter PNIPAM arms ofPPconjugates lead to a lower phase-separation temperature (Tp). The concentration dependency of the size of the cooperative domain was also determined. BelowTp, experimental data indicate thatPPbehaves as a 1D supramolecular polymer with a concentration-dependent length, while aboveTp,PPglobules adopt a larger spherical shape. Various temperature–pH reversible and irreversible interdependencies (“cross-effects”) between phase separation and protonation were observed. ThePPconjugates represent a dual temperature–pH-responsive model system possessing various aggregated states, making them candidates for visual indicators, pH or temperature sensors, or singlet oxygen generators for biomedical applications.