Laser‐induced decomposition of 2,2‐dimethoxy‐2‐phenylacetophenone and benzoin in methyl methacrylate homopolymerization studied via matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry
Laser‐induced decomposition of 2,2‐dimethoxy‐2‐phenylacetophenone and benzoin in methyl methacrylate homopolymerization studied via matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry
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DOI：
10.1002/pola.10150
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发表时间：
2002-03
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影响因子：
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通讯作者：
C. Barner‐Kowollik;Philipp Vana;T. P. Davis
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文献类型：
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作者：
C. Barner‐Kowollik;Philipp Vana;T. P. Davis
在-34℃下对甲基丙烯酸甲酯(MMA)的本体聚合进行了脉冲激光聚合(PLP)实验。本研究的目的是通过基质辅助激光解吸/电离飞行时间 (MALDI-TOF) 质谱法研究使用 2,2-二甲氧基-2-苯基苯乙酮 (DMPA) 和安息香作为引发剂的 MMA 单体光引发过程中形成的聚合物端基。 MALDI-TOF 光谱分析表明，脉冲激光照射产生的两个自由基片段对 MMA 表现出明显不同的反应性：而 DMPA 和安息香共有的苯甲酰片段明显参与引发过程，而缩醛和苯甲醇片段不能被识别为聚合物中的端基。 MALDI-TOF 光谱的复杂性随着激光强度的增加而急剧增加，这种效应在安息香的情况下更为明显。这表明当使用 DMPA 作为光引发剂时，更清洁的引发过程正在发挥作用。此外，还分析了 MALDI-TOF 光谱，以提取 -34 ℃ 下 MMA 的传播速率系数 k(p)。获得的 k(p) = 43.8 L mol(-1) s(-1) 值与通过尺寸排阻色谱法获得的相应数字 (k(p) = 40.5, L mol(-1) s(-1)) 非常吻合。 (C) 2002 约翰·威利儿子公司
Pulsed laser polymerization (PLP) experiments were performed on the bulk polymerization of methyl methacrylate (MMA) at -34 degreesC. The aim of this study was to investigate the polymer end groups formed during the photoinitiation process of MMA monomer using 2,2-dimethoxy-2-phenylacetophenone (DMPA) and benzoin as initiators via matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Analysis of the MALDI-TOF spectra indicated that the two radical fragments generated upon pulsed laser: irradiation show markedly different reactivity toward MMA: whereas the benzoyl fragment-common to both DMPA and benzoin-clearly participates in the initiation process, the acetal and benzyl alcohol fragments cannot be identified as end groups in the polymer. The complexity of the MALDI-TOF spectrum strongly increased with increasing laser intensity, this effect being more pronounced in the case of benzoin. This indicates that a cleaner initiation process is at work when DMPA is used as the photoinitiator. In addition, the MALDI-TOF spectra were analyzed to extract the propagation-rate coefficient, k(p), of MMA at -34 degreesC. The obtained value of k(p) = 43.8 L mol(-1) s(-1) agrees well with corresponding numbers obtained via size exclusion chromatography (k(p) = 40.5, L mol(-1) s(-1)). (C) 2002 John Wiley Sons, Inc.