Micromolecule Chemistry Experiment

Chemical Experiments Micromolecule Chemistry Experimental Study Wang Yazhen Xu Qun Ma Liqun Li Qingshan (College of Chemistry and Chemical Engineering, Qiqihar University, Qiqihar 161006) Assay device and research institute have designed a micromanipulator chemical experiment program with strong operability.

1 Introduction Polymer chemistry is an important technical basic course for polymer materials and related specialties. The polymer chemistry experiment is an important means for students to further understand and master the basic methods of polymer synthesis, macromolecular reaction, and polymer structure characterization and to cultivate students' practical ability. In polymer chemistry experiments, conducting miniaturization research not only meets the needs of reforms in the contents, methods, and means of experimental teaching in higher education institutions, but also complies with the "Chemistry of Chemistry" proposed by the Green Chemistry Challenge Program since the 1990s. It is chemists in the 21st century. We must study the trend of the times in the primary area of ​​research." Micro-chemistry experiments must be accelerated in order to adapt to the requirements of high-speed development of the times and protect the environment in which human beings live.

However, the polymer chemical reaction is different from the inorganic chemistry and organic chemical reaction, and has the characteristics of high relative molecular mass of the product, large viscosity of the reaction system, frequent heating of the reaction process, and long reaction time, which brings about the miniaturization of the polymer chemistry experiment. There are many difficulties. Based on the actual situation of our university, we learned from other micro-chemical experiment methods, and through repeated experiments and repeated explorations, we successfully developed the MPC-3 micro-molecule chemical experimental device and transformed a number of experimental instruments and equipment. We have developed more than a dozen experimental methods for the miniaturization of polymer chemistry experiments, and we have compiled micro-polymer chemistry experimental techniques (China Textile Industry Press) and promoted and applied them in polymer chemistry experimental teaching in many colleges and universities in China.

2 Development of Micro-Polymer Chemistry Experimental Device The polymer molecular experimental product has high relative molecular mass, high viscosity, and long reaction time. The reaction vessel, heater, stirrer, condenser tube, and temperature control device are required in the experiment. The amount of reagents used in micromolecule chemistry experiments is 0.1% to 1% of the constant experiment. The wall-hanging effect and mixing uniformity of reagents have become an important factor affecting the success of the experiment. We must consider the problem of the reaction device that is matched with the micro-reagent. Therefore, our research work begins with the miniaturization of the experimental device.

According to the characteristics of the polymer chemical reaction, after repeated trials, the MPC-3 type micro-polymer chemical experiment device was successfully developed. This device is particularly suitable for the heating and stirring of high-viscosity reaction systems. The MPC-3 micro-molecule chemical experiment device consists of a stirring device, a heating water (oil) bath device, a temperature control speed governing device, and a fixed locking device.

/= 150mm stainless steel mixing rod with PTFE plastic (or stainless steel) blade to complete the mixing task, speed 0 ~ 2400 rpm / min, stepless speed regulation.

(2) The heating water bath (oil bath) device is made of stainless steel material, the bottom is equipped with electric heating device, and is equipped with a small thermocouple and other temperature measuring elements. The bath temperature can be arbitrarily selected and controlled at 20~300C.

(4) The fixed locking device consists of a small iron frame, a universal joint, a motor locking mechanism, a coupling, a microreactor, and a reactor clamping mechanism.

MPC-3 type micro-polymer chemical experiment device has a small size (can be installed in a 300mm square small box), light weight, energy saving (energy saving 90%), flexible and other features, the cost is relatively low. Most macromolecular chemistry experiments can be conducted.

3 Micro-molecule chemistry Experimental methods, schemes for exploration and research Miniaturized polymer chemistry experiments are scaled down to a very limited number of experiments, each of which has its own characteristics. We have carefully studied the objectives, requirements, problems to be solved, etc. of each experiment, and then determined scientific and reasonable experimental methods and programs.

For example, the bulk polymerization experiment of methyl methacrylate aims to let students understand the characteristics of free radical polymerization and the principle of bulk polymerization, and grasp the relationship between polymerization rate, initiator concentration, and monomer concentration, ie, in routine experiments. Usually, the monomers with different initiator concentrations dissolved and deeper (2%, 1%, 0.5%, etc.) on the “time-conversion” curve are recognized at the same temperature (generally 70C) after the same reaction time. Stop the reaction, dry and weigh, calculate the conversion rate, and establish the time-conversion curve. However, in the micro experiments, due to the small amount of reactants and products, such as the above method, it will inevitably cause a large system error, so that the experimental results are not credible. To this end, we changed the experimental method to achieve the same conversion rate (approximate, judging by the intuitive sense of reaction system viscosity, curing state, hardness, etc.) to establish the time-conversion rate between The relationship curve, the actual operation is intuitive, convenient and feasible, students are easy to master, and the teaching effect is good.

In order to reduce the error in the micro-scale experiment, we use constant weighting for the soluble solid sample. The constant dissolves the method for the group of students to take the sample from this dissolved sample. For the sampling of the liquid sample, the sample is moved. The liquid tube, not the cylinder, ensures the accuracy of the quantitative experiment.

4 Conclusion The teaching practice of micro-polymer chemistry experiment shows that compared with the conventional experiment, the micro-molecule chemistry experiment completely meets the requirements of the syllabus. As the micro-device is delicate and novel, it helps to increase students' interest in the experiment. At the same time, because students experiment with a small amount of reagents in the micro-instrument, the students are required to perform more careful and careful operation, which helps to train and train students' basic skills. In addition, due to the miniaturization of experimental instruments and equipment and the small amount of reagents, the equipment investment and experimental consumables costs are greatly reduced, environmental pollution is small, and safety is high. It is of great practical significance to develop and promote miniature polymer chemistry experiments.