Chapter 3
                  Chapter 3
              Molecular Weight
              Molecular Weight
        1. Thermodynamics of Polymer Solution
        2. Mol Wt Determination
         1. Weight, shape, and size of polymers
         1. Weight, shape, and size of polymers
           monomer – oligomer – polymer
              dimer, trimer, ---
              telomer ~ oligomer from telomerization (popcorn polymerization)
              telechelic polymer ~ with functional group
              macro(mono)mer ~ with polymerizable group [wrong definition 	p72]
              pleistomer ~ mol wt > 1E7
           usual range of mol wt of polymers
              25000 ~ 1E6
              mol wt of chain polymers are higher 
           molecular weight  conformation Æ shape      molecular size
              LS (solution) and SANS (bulk) determine size.
              DSV and GPC utilize this relation in solution.
                                                               Ch 3-1 Slide 2
         2. Solution
          2. Solution
            ΔG = ΔH –T ΔS
                m        m          m
                                                    m for mixing
                                                    f for melting (fusion)
               ΔSm > 0  always 
               ΔHm > 0  almost always
                   “like dissolves like”
                   ΔHm = 0 at best (when solute is the same to solvent)
                   if not, ΔHm > 0
                   ΔHm < 0 only when specific interaction like H-bonding exists
               For solution, ΔH < T ΔS
                                 m         m
                                                                     Ch 3-1 Slide 3
         Solubility parameter
         Solubility parameter
                                    ½              ½ 2               : solvent
            ΔH = V [(ΔE /V ) –(ΔE /V ) ] v v                        1
               m      m       1   1          2   2        1 2        : solute
                  = V [δ – δ ]2 v v                                 2
                       m    1    2     1 2
               ΔE ~ cohesive energy ~ energy change for vaporization
                  ΔE = ΔH     –PΔV ≈ ΔH    –RT  [J]
                          vap            vap
               ΔE/V ~ cohesive energy density  [J/cm3 = MPa]
                                               ½
               δ ~ solubility parameter [MPa ]
                       ½        6     2 ½          3 ½                 3 ½
                  [MPa ] = [(10 N/m ) ] = [(J/cm ) ] ≈ [(1/2)(cal/cm ) ]
                                                      	Table 3.1 & 3.2
                                                                   Ch 3-1 Slide 4