简介:A poly(glycerol monomethacrylate)-block-poly(2-(dimethylamino)ethyl methacrylate)-blockpoly(
2-(diethylamino)ethyl methacrylate) (GMA-DMA-DEA) triblock copolymer was synthesized via atom
transfer radical polymerization简介:A poly(glycerol monomethacrylate)-block-poly(2-(dimethylamino)ethyl methacrylate)-blockpoly(
2-(diethylamino)ethyl methacrylate) (GMA-DMA-DEA) triblock copolymer was synthesized via atom
transfer radical polymerization (ATRP). The pH-induced micellization kinetics of this GMA-DMA-DEA
triblock copolymer was investigated by employing a stopped-flow light scattering technique. Upon jumping
from pH 4 to around 7-7.5, stopped-flow experiments revealed two distinct relaxation processes. The
first relaxation mode had a positive amplitude, suggesting that the micelle size and/or micelle number
density increases; in contrast, the second relaxation mode had a negative amplitude, which is assigned
to the micelle formation-breakup process. However, upon jumping from pH 4 to pH >8, only relaxation
processes with positive amplitude were observed. The relaxation curve can be well fitted with a doubleexponential
function, leading to a fast relaxation time constant (ô1) and a slow relaxation time constant
(ô2). ô1 is in the range 10-20 ms, which decreases with increasing polymer concentration. ô2 is around
110 ms, which is independent of concentration in the range studied. In the fast process (ô1), quick
association of unimers into small micelles and fusion between small micelles result in the birth of quasiequilibrium
micelles (with aggregation number per micelle still lower than that of equilibrium micelles)
by consuming large amounts of excess unimers; the unimer concentration is close to the critical
micellization concentration (cmc) at the end point of the fast process.详细>