Polymer Synthesis

 The synthesis made use of an 8-methylene spacer acid to improve the rate of

polymerization by reducing the likelihood of complexation forming between the alkene

and the ruthenium atom in the 2nd generation Grubbs' catalyst (Figure 1). The

polycondensation reactions (Figure 6) were run using a 250:1 monomer to catalyst ratio.

This ratio was settled upon following brief experiments to determine the best ratio to

ensure high polymer. Monomers 3-5 were polymerized in the bulk under full vacuum

(0.01 mm Hg). Polymerizing in the bulk helps to minimize ring-closing metathesis by

lowering the local concentration of the polymer's chain end alkenes versus the high local

concentration of other monomer molecule's terminal alkenes. The solid monomers

required the use of solvent for the polymerizations. The best solvent for these monomers

has proven to be THF. The molecular weights for the polymers produced in THF are

much higher than in other solvents. This phenomenon may be due the THF molecule

aiding in the dissociation of the PPh3, which is necessary to initiate the polymerization.

 0 R 2 (.5 mol%) O R
 0 0
 H 0 DryTHFor H 0 n
 1 -6 bulk monomer 7 12


 R= H 1,7
 CH3 2,8
 CH(CH3)2 3, 9 2
 CH2CH(CH3)2 4, 10 2
 CH(CH3)CH2CH3 5, 11 2
 CH2(C6Hs) 6, 12

Figure 6 Polymerization reaction for monomers 1-6

 For the polymerization of monomers 1,2 and 6, the local concentration of terminal

alkenes is kept at a high level by adding only a few milliliters of solvent every 4-6 hours