Atom transfer radical suspension polymerization of methyl methacrylate

Atom transfer radical suspension polymerization (ATRP) of methyl methacrylate (MMA) was conducted at 80 degreesC using 1-phenylethyl chloride (1-PECl) as initiator, cuprous chloride(CuCl) as catalyst and 1, 1-bipyridine (Bpy) as ligand. The polymerization was carried out with a mechanical agitator under the protection of nitrogen atmosphere. In addition of the dispersing agent, NaCl was also used in the water phase to prevent the diffusion of the catalyst complex into water. The results show that the polymerization is a first order reaction with respect to monomer concentration. From the slop of the plot of In[M](0)/[M] versus time, the concentration of the propagating radical was calculated as 5.74 x 10(-8) mol/L. The polymerization displayed living character as evidenced by a linear increase of molecular weight with conversion and a relatively narrow molecular weight distribution (M-w/M-n ranged from 1.37 to 1.40). Subsequently the reverse ATRP of MMA at 80 degreesC was conducted using AIBN as initiator, FeCl3 and triphenylphosphine (PPh3) as catalysts. The results indicate that the bulk polymerization demonstrated good control. The molecular weight increased with conversion and the M-w/M-n ranged from 1.27 to 1.31. The polymerization rate is quite fast. The conversion approached to 75.6% after 2 It. From the linear plot of In[ M](0)/[M] versus time, the concentration of the growing radical was calculated as 1. 64 x 10(-7) mol/L. However the suspension polymerization of MMA using this initiation-catalyst system failed as evidenced by the large molecular weight (ca. 100,000) and large value of M-w/M-n (4.8 similar to 6.32).