CHEMBIO 3BM3 Lecture Notes - Lecture 6: Molar Mass Distribution, Dispersity, Weight Distribution
21 Apr 2019
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Total number of structural units, including end-groups. If you don"t know how many units in a polymer, assume 100 units: don"t want polymers too small, if it"s bigger than a certain amount, they"re sure they won"t get into cells, so they"re not worries about them. The variation in dp from chain to chain within a polymer sample. Due to polydispersity, we discuss average dp-dp. More chain interaction = more viscosity: like straight wire fence sliding against each other vs barbed wire, which gets stuck within itself. If you have 1 kg of polyethylene with a mw of 10000 da: could have multiple, varying, amounts of polymer chains, not all the chains would be the same length. Small molecules have a unique molecular weight whereas polymers have a molecular weight distribution. Value of mw measurements depend on technique. Like lego blocks, all monomers are the same weight but we can"t assume the chains are the same length.
