Synthesis of a ROS-responsive analogue of poly(ε-caprolactone) by the living ring-opening polymerization of 1,4-oxathiepan-7-one†,Polymer Chemistry

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Synthesis of a ROS-responsive analogue of poly(ε-caprolactone) by the living ring-opening polymerization of 1,4-oxathiepan-7-one†
Polymer Chemistry ( IF 4.1 ) Pub Date : 2018-08-08 00:00:00 , DOI: 10.1039/c8py00798e
Linggao Li _{1,

2,

3,

4,

5} , Qiyuan Wang _{1,

2,

3,

4,

5} , Ruiliang Lyu _{1,

2,

3,

4,

5} , Li Yu _{1,

2,

3,

4,

5} , Shan Su _{1,

2,

3,

4,

5} , Fu-Sheng Du _{1,

2,

3,

4,

5} , Zi-Chen Li _{1,

2,

3,

4,

5}

Affiliation

We report the synthesis of a poly(ε-caprolactone) (PCL) analogue containing thioether groups in the main chain by living ring-opening polymerization (ROP) of 1,4-oxathiepan-7-one (OTO). OTO was synthesized by a one-pot two-step method, and the ROP of OTO was conducted at 30 °C in dichloromethane with benzyl alcohol (BnOH) as the initiator and diphenyl phosphate (DPP) as the catalyst. The livingness of the polymerization was verified by polymerization kinetics and chain-extension experiment with ε-caprolactone (CL). Well-defined POTO and POTO-b-PCL with predetermined molecular weights and low dispersities were thus obtained. Furthermore, with monomethyl poly(ethylene oxide) (PEO) as the macroinitiator, diblock and triblock amphiphilic block copolymers, namely, PEO-b-POTO, PEO-b-POTO-b-PCL and PEO-b-PCL-b-POTO, were also prepared. Several small model molecules mimicking the β-thioether ester moieties in POTO were synthesized, and their H₂O₂-responsive properties in aqueous media were investigated in detail by NMR and MS. Upon exposure to excess H₂O₂, the thioether moieties rapidly and exclusively converted to sulfoxides within a few hours, and then hydrolysis of the ester groups adjacent to the sulfoxide occurred together with elimination reactions. Finally, using PEO₁₁₄-b-POTO₂₀ as an example, the H₂O₂-oxidized disassembly of the polymer micellar nanoparticles in aqueous solution was investigated by NMR, TEM, GPC, and DLS. We confirmed that although the oxidation of the thioether groups enhanced the hydrophilicity of POTO and contributed to the disassembly of the PEO₁₁₄-b-POTO₂₀ nanoparticles, the main driving force of nanoparticle disassembly was the oxidation-promoted hydrolysis of the POTO block.

中文翻译：

通过1,4-oxathiepan-7-one的活性开环聚合反应合成聚（ε-己内酯）的ROS反应类似物†

我们报告了1,4-oxathiepan-7-one（OTO）的活开环聚合（ROP），合成了在主链中包含硫醚基团的聚（ε-己内酯）（PCL）类似物。通过一锅两步法合成OTO，并在30℃在二氯甲烷中以苄醇（BnOH）为引发剂和磷酸二苯酯（DPP）为催化剂进行OTO的ROP合成。通过聚合动力学和ε-己内酯（CL）的扩链实验验证了聚合的活性。由此获得具有预定分子量和低分散度的明确的POTO和POTO- b -PCL 。此外，以一甲基聚环氧乙烷（PEO）作为大分子引发剂，可形成二嵌段和三嵌段两亲性嵌段共聚物，即PEO- b- POTO，PEO-b -POTO- b -PCL和PEO- b -PCL- b -POTO，还制备。合成了一些模拟POTO中β-硫醚酯部分的小分子模型，并通过NMR和MS详细研究了它们在水介质中对H ₂ O _2的响应特性。一旦暴露于过量的H ₂ O ₂，硫醚部分在数小时内迅速且排他地转化为亚砜，然后与亚砜相邻的酯基团的水解与消除反应一起发生。最后，以PEO ₁₁₄ - b -POTO ₂₀为例，H ₂ O通过NMR，TEM，GPC和DLS研究了聚合物胶束纳米粒子在水溶液中的_2-氧化分解。我们证实，尽管硫醚基团的氧化增强了POTO的亲水性并有助于PEO₁₁₄ - b -POTO₂₀纳米粒子的分解，但纳米粒子分解的主要驱动力是氧化促进的POTO嵌段水解。

更新日期：2018-08-08

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