The living polymerization of methyl vinyl ether (MeVE) was
achieved using initiators
obtained by capping 2,4,4-trimethyl-2-chloropentane (TMPCl) with
1,1-diphenylethylene (DPE), or 1,1-ditolylethylene (DTE) in conjunction with
TiCl
n
(OEt)4
-
n
(n = 2−2.4) coinitiator in
CH2Cl2/hexanes (60/40
v/v) solvent mixture at 0 °C. Sequential block copolymerization
of isobutylene (IB) with MeVE has also
been accomplished. Well-defined living poly(isobutylene)
(PIB) was first prepared at −80 °C in the
presence of TiCl4, followed by capping with DPE or DTE.
Then, Ti(OEt)4 was added to reduce the
Lewis
acidity followed by the addition of MeVE, and the temperature was
raised to 0 °C. Well-defined PIB-PMeVE diblock copolymers with controlled molecular weight and narrow
molecular weight distribution
(M
w/M
n < 1.1) have been
obtained, with the virtual absence of homopolymer contaminants.
According to
differential scanning calorimetry, the diblock copolymers exhibit two
T
gs, suggesting microphase
separation. PIB-PMeVE diblock copolymers with ∼50/50 w/w
composition were insoluble in water but
soluble in methanol. The diblock copolymer with 80 wt % PMeVE
content was soluble in water, exhibited
excellent surfactant properties (critical micelle concentration = 2.3
× 10-5 M), and produced stable
emulsions of oil in water (average particle size ∼200
nm).