Lab Tour - Polymer Chemistry at Cornell University 

Thanks for the question! A catalyst and an initiator are often very different when thinking about polymerization processes. In general, a catalyst must be regenerated after each cycle of a chemical reaction and for small molecule chemistry, it helps by speeding up the reaction. In the case of an initiator for polymers, the initiator actually forms a chemical bond with the first monomer, allowing for polymer synthesis to occur. In the case of styrene (let's call this M for monomer) polymerization, the initiator that we used in this video was an anion (let's call it I) that reacts with one monomer to form a new bond (we would get I-M as a new bond). I-M can then react with another monomer to form (I-M-M) and so forth to get our polymer (I-M-M-M-M-M). So when you are done making your final polymer, the initiator can often be found on the end of the polymer chain. However, there are some cases where a "catalyst" is acting as an initiator and a lot of times, it just becomes semantics. Often, when talking about the synthesis of polyethylene, for example, (polyethylene makes up a lot of milk jugs, plastic bags, and storage containers), we refer to these initiators as catalysts because of how the process of polymerization occurs. Hopefully that made some sense, but if not, please let us know!

Great question! So we added water to basically "stop" the reaction and make the final polymer come out of solution. In this polymerization, water is a great way to make sure that we stop the reaction and prevent it from continuing to form more polymer or any side products. And, just as you said, because water is polar and styrene/polystyrene are non-polar, it helps us acquire our final polymer because it does not want to dissolve in water (or Methanol either!). Does that make sense? let us know

In another she is quenching the reaction

Thanks 😊

@@forsresearchgroup8708 ممكن ان تعلمنا كيف صنع دهان مائي الطريقه كيف