Dyeing to Degrade: A Bioplastics Experiment for College and High School Classrooms
Dyeing to Degrade: A Bioplastics Experiment for College and High School Classrooms
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DOI：
10.1021/acs.jchemed.9b00461
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发表时间：
2019-11-01
影响因子：
3
通讯作者：
Wissinger, Jane E.
中科院分区：
文献类型：
--
作者：
Knutson, Cassandra M.;Hilker, Abby P.;Wissinger, Jane E.
描述了一种针对高中和大学实验室环境的多功能实验，该实验基于由廉价、可再生且无害的化学品制备的生物基聚合物的合成。使用容易获得的柠檬酸、甘油和木薯根淀粉的组合来制备三种具有不同可观察到的物理性质的聚合物材料。可以对水降解率进行简单的定性比较，或者可以添加染料进行定量评估。选择食品和药物管理局 (FDA) 批准的黄色染料 5 号作为对碱性条件稳定的染料，并以商业食用色素的形式添加到每个样品中。观察到染色的聚合物样品在氢氧化钠水溶液中降解，释放染料。紫外-可见光谱和智能手机比色法都用于跟踪染料浓度的增加，这与聚合物降解成反比。收集的数据适合学生分析和绘图。实验的潜在学习成果包括勒夏特列原理、分子间力的类型、水解、吸收光谱、比尔定律、速率测定和绘图。该实验模拟了绿色化学设计原理，以实现更安全的化学品、降解和可再生原料的使用。该课程的教育目标最重要的是与在环境中积累并造成危害的塑料的社会联系，以及聚丙交酯（PLA）等商业生物塑料的成功进展的例子。
A versatile experiment is described for the high school and college laboratory setting based on the synthesis of biobased polymers prepared from inexpensive, renewable, and nonhazardous chemicals. Combinations of readily available citric acid, glycerol, and tapioca root starch are used to prepare three polymeric materials with different observable physical properties. Simple qualitative comparisons of aqueous degradation rates can be made or a dye can be added for quantitative assessment. Food and Drug Administration (FDA) approved Yellow Dye No. 5 is selected as a dye stable to basic conditions and is added to each sample in the form of commercial food coloring. The dyed polymer samples are observed to degrade in an aqueous sodium hydroxide solution, releasing the dye. Both ultraviolet-visible spectroscopy and smartphone colorimetry are used to follow the increasing dye concentration, which is inversely correlated to polymer degradation. The collected data is suitable for analysis and graphing by students. Potential learning outcomes of the experiment include Le Chatelier's principle, types of intermolecular forces, hydrolysis, absorption spectroscopy, Beer's Law, rate determinations, and graphing. The experiment models green chemistry principles of design for safer chemicals, degradation, and use of renewable feedstocks. Paramount to the educational objectives of the curriculum are the societal connections to plastics that are accumulating in the environment and causing harm, as well as examples of successful advances in commercial bioplastics such as poly(lactide) (PLA).