The 1:1 alternating copolymerisation of styrene (St) and methyl methacrylate (MMA) in toluene and methylene chloride in the presence of Lewis acids (Et1.5AlCl1.5, ZnCl2, Br-3 and BCl3) has been re-visited with a view to loping a high yielding preparative procedure. Only photo-irradiation in the presence of BCl3 offered the prospect of clean and high conversions. Manipulation of the temperature, comonomer concentration and the comonomer: ratio has allowed yields of 1:1 alternating copolymer aching 100% to be achieved. BCl3 is required only at catalytic levels and so the Lewis acid does turnover in the course of the reactions. Astonishingly the molecular weights of the product, turn out to be very high for a solution polymerisation, with (M) over bar (w) up to ca. 2 000 k being readily cued. Furthermore, the molecular weight was shown to with conversion and in many cases the molecular it distributions are narrow. Though there are some features of a free radical mechanism, the process is more complex with side reactions possibly contributing to the growth in molecular weight. Overall use of BCl3 with photo-irradiation does offer a viable preparative route to exploitable quantities of 1:1 alternating St/MMA copolymers.
|Number of pages||8|
|Journal||Macromolecular Chemistry and Physics|
|Publication status||Published - 29 Jul 2002|
- alternating copolymerization
- Lewis acid