Application of an addition–fragmentation-chain transfer monomer in di(meth)acrylate network formation to reduce polymerization shrinkage stress,Polymer Chemistry

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Application of an addition–fragmentation-chain transfer monomer in di(meth)acrylate network formation to reduce polymerization shrinkage stress
Polymer Chemistry ( IF 4.1 ) Pub Date : 2017-06-21 00:00:00 , DOI: 10.1039/c7py00702g
Parag K. Shah _{1,

2,

3,

4} , Jeffrey W. Stansbury _{1,

2,

3,

4,

5} , Christopher N. Bowman _{1,

2,

3,

4}

Affiliation

A new addition–fragmentation chain transfer (AFT) capable moiety was incorporated into a dimethacrylate monomer that participated readily in network formation by copolymerizing with multifunctional methacrylates or acrylates. The process of AFT occurred simultaneously with photopolymerization of the AFT monomer (AFM) and other (meth)acrylate monomers leading to polymer stress relaxation via network reconfiguration. At low loading levels of the AFM, a significant reduction in shrinkage stress, especially for acrylate monomers, was observed with nominal effects on conversion. At higher loading levels of the AFM, the photopolymerization reaction kinetics and final double bond conversion were significantly lowered along with a delay in the gel-point conversion. Electron paramagnetic resonance studies during polymerization revealed the presence of a distinct radical species that was present in proportional quantities to the AFM content in the system. The lifetime and the character of the persistent radicals were altered due to the presence of the distinctive radical, in turn affecting the polymerization kinetics. With polymerization conducted at higher irradiance, the differential conversion between the control resin and samples with moderate AFM content was minimal, especially for the methacrylate-based formulations.

中文翻译：

加成-断裂链转移单体在二（甲基）丙烯酸酯网络形成中的应用以降低聚合收缩应力

一种新的具有加成-断裂链转移（AFT）功能的部分被掺入到二甲基丙烯酸酯单体中，该单体通过与多官能甲基丙烯酸酯或丙烯酸酯共聚而易于参与网络形成。AFT的过程与AFT单体（AFM）和其他（甲基）丙烯酸酯单体的光聚合同时发生，从而导致通过网络重新配置。在AFM的低负载水平下，观察到收缩应力的显着降低，尤其是丙烯酸酯单体的收缩应力，这对转化率产生了名义影响。在较高的AFM负载量下，光聚合反应动力学和最终的双键转化率显着降低，并且胶凝点转化延迟。聚合过程中的电子顺磁共振研究表明存在明显的自由基物质，该自由基物质与系统中AFM的含量成比例。持久性自由基的寿命和特征由于独特自由基的存在而改变，进而影响聚合动力学。在较高的辐照度下进行聚合

更新日期：2017-08-02

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