ISSN:
0887-6266
Keywords:
intrachain coil-to-globule transition
;
interchain aggregation
;
laser light scattering
;
poly(N-isopropylacrylamide)
;
single-chain nanoparticle
;
Physics
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
The coil-to-globule transition of two poly(N-isopropylacrylamide) (PNIPAM) ionomers with different ionic contents (0.8 and 4.5 mol %), but similar weight average molar masses, in deionized water was investigated by a combination of static and dynamic light scattering. In spite of the large difference in their ionic contents, both the ionomers have a nearly same lower critical solution temperature (LCST, ∼ 32.5°C). At temperatures higher than the LCST, the ionomer chains undergo a simultaneous intrachain coil-to-globule transition and interchain aggregation to form nanoparticles thermodynamically stable in water. The average size of the nanoparticles decreases respectively as the ionic content increases and the ionomer concentration decreases. The interchain aggregation can be completely suppressed in an extremely dilute ionomer solution (〈 ∼ 5 × 10-6 g/mL), so that the intrachain coil-to-globule transition leads to the collapse of the ionomer chains into individual single-chain nanoparticles. Our results clearly indicate that there is a hysteresis in the colling process (the globule-to-coil transition). © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1501-1506, 1998
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
