Synthesis, Thiol-Yne "Click" Photopolymerization, and Physical Properties of Networks Derived from Novel Multifunctional Alkynes
Synthesis, Thiol-Yne "Click" Photopolymerization, and Physical Properties of Networks Derived from Novel Multifunctional Alkynes
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DOI：
10.1021/ma1004452
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发表时间：
2010-06-08
期刊：
影响因子：
5.5
通讯作者：
Lowe, Andrew B.
中科院分区：
文献类型：
--
作者：
Chan, Justin W.;Shin, Jungwhan;Lowe, Andrew B.
利用亲核试剂催化的硫代迈克尔加成反应，由市售的多官能硫醇（2、3或4个硫醇）和丙烯酸炔丙酯制备多官能炔（每个单体2、3或4个炔）。实时FTIR（RTIR）和NMR光谱表明，在这些条件下的共轭加成进行到高转化率在几秒钟内使用亲核催化剂二甲基苯基膦，在没有溶剂。在环境温度下，并且没有副产物。通过光引发的硫醇-炔反应，采用2：1的硫醇与炔的比例制备了一系列聚合物网络，这导致了系统地增加交联密度的均匀交联的材料。光聚合动力学曲线表明硫醇-炔反应快速进行到高转化率，转化率随着硫醇和/或炔基团的官能度的增加而降低。差示扫描量热法（DSC）和动态机械热分析（DMTA）结果清楚地表明，玻璃化转变温度随着总交联密度的增加而增加（通过DMTA从-10 ℃增加到42 ℃）。随着官能度的增加，橡胶态模量（在70 ℃下从6 MPa增加到23 MPa）增加，同时交联之间的分子量降低。
Multifunctional alkynes (2, 3, or 4 ynes per monomer) were prepared utilizing the nucleophile-catalyzed thio Michael addition reaction from commercially available multifunctional thiols (2, 3, or 4 thiols) and propargyl acrylate. Real-time FTIR (RTIR) and NMR spectroscopies indicate that the conjugate addition under these conditions proceeds to high conversions within seconds using the nucleophilic catalyst dimethylphenylphosphine, in the absence of solvent. at ambient temperature, and with no side products. A family of polymer networks was prepared by the photoinitiated thiol-yne reaction employing a 2:1 ratio of thiol to alkyne, which resulted in uniformly cross-linked materials of systematically increasing cross-link density. Photopolymerization kinetic profiles indicate that the thiol-yne reaction proceeded rapidly to high conversion with conversions decreasing with increasing functionality of the thiol and/or alkyne groups. Differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) results clearly indicate that the glass transition temperature increases as the overall cross-link density increases (from -10 to 42 degrees C by DMTA). An increase in the rubbery modulus (from 6 to 23 MPa at 70 degrees C) results as the functionality increases, with a concomitant decrease in the molecular weight between cross-links.