Photolysis of Poly[1-(4-substituted phenyl)-2-propen-1-one] in the solid phase

P. Hrdlovič , J.E. Guillet
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引用次数: 5

Abstract

Photolysis of poly[1-(4-substituted phenyl]-2-propen-1-ones] in film of thickness 5–10 μm was followed by automatic viscometry, lowangle laser light scattering (LALLS) and gel permeation chromatography (GPC) under irradiation at 313 and 285·8 nm in air. The substituents in position 4 of the benzene ring were: H, fluoro, chloro, methoxy and ethyl. The monitoring of degradation by automatic viscometry and LALLS enabled determination of the Mark-Houwink parameters α and K for the above polymers in chlorobenzene at 25°C as follows. H: α = 0·76 ± 0·03, K = 3·8 × 10−3; 4-F: α = 0·69 ± 0·02, K = 6·1 × 10−3; 4-Cl: α = 0·79 ± 0·03, K = 1·4 × 10−3; 4-C2H5: α = 0·85 ± 0·03, K = 1·3 × 10−3; 4-OCH3: α = 0·75 ± 0·06, K = 2·3 × 10−3. The plots of main chain scission versus time were curved, which indicates inhibition at the later stage of degradation. The initial quantum yields of main chain scissions are about 0·08 except for the 4-methoxy derivative, in which case strong oxygen quenching causes the quantum yield to lie one order of magnitude lower. The unsaturated ketone formed during photolysis quenches the main chain scissions with Stern-Volmer constants which lie within the range 50–150 mol−1 for the polyketones under study.

聚[1-(4-取代苯基)-2-丙烯-1- 1]在固相中的光解反应
在313和285·8 nm的空气辐照下,对厚度为5-10 μm的聚[1-(4-取代苯基]-2-丙烯-1-ones]薄膜进行光解实验,采用自动粘度测定、低角度激光散射(LALLS)和凝胶渗透色谱(GPC)。苯环第4位的取代基为:氢、氟、氯、甲氧基和乙基。采用自动粘度法和LALLS对上述聚合物在25°C氯苯中的降解进行监测,测定了Mark-Houwink参数α和K如下。H: α = 0.76±0.03,k = 3.8 × 10−3;4-f: α = 0.69±0.02,k = 6.1 × 10−3;4- cl: α = 0.79±0.03,K = 1.4 × 10−3;4-c2h5: α = 0.85±0.03,k = 1.3 × 10−3;4-och3: α = 0.75±0.06,k = 2.3 × 10−3。主链断裂随时间曲线变化,表明在降解后期有抑制作用。除4-甲氧基衍生物外,主链断裂的初始量子产率约为0·08,在这种情况下,强氧猝灭使量子产率降低了一个数量级。在光解过程中形成的不饱和酮猝断主链,其Stern-Volmer常数在50-150 mol−1范围内。
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CiteScore
1.20
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