[[Polymer Solutions]] ## Molar mass M<sub>n</sub> (num avg molar mass): ==How many molecules are in here?== - Uses **colligative** properties - depend on # of solute species present per volume - Can be used for branched + linear, homopolymers + copolymers - Gives N (# molecules), x<sub>n</sub> = N/N<sub>0</sub> (N<sub>0</sub> = initial monomers), M<sub>n</sub> M<sub>0</sub>x<sub>n</sub> - Vapor pressure lowering, Boiling pt elevation, Freezing pt depression ### Method: Osmometry Polymer solution separated from pure solvent by semi-permeable membrane - Height of solution gives osmotic pressure: π = hρ<sub>0</sub>g - Chemical potential: μ<sub>1</sub>- μ<sub>1</sub><sup>0</sup> \= - - End group analysis ## Molar mass distribution ### Methods: Size exclusion chromatography, Gel permeation chromatography, Mass spectrometry ## Conformation ==Is the polymer coiled or elongated?== ### Methods: Light scattering in solution ## T<sub>m</sub> and T<sub>g</sub>: [[glass and melting transitions]] ==How does the polymer respond to changes in temperature?== ### Methods [[Differential scanning calorimetry]] (DSC): heat flow vs temperature ## Chemical composition ==Did I synthesize the polymer I intended? Does it have tacticity?== ### Methods UV/Vis spectroscopy, IR spectroscopy, Raman spectroscopy, Nuclear magnetic resonance (NMR)