Abstract
Star polymers with a hydrophobic cholane core and four poly(ethylene glycol) (PEG) arms, CA(EGn)4, have been synthesized by anionic polymerization. Pulsed-gradient spin-echo NMR spectroscopy was used to study the diffusion behavior of the star polymers, ranging from 1000 to 10,000g/mol, in aqueous solutions and gels of poly(vinyl alcohol) (PVA) at 23°C. The star polymers have a lower self-diffusion coefficient than linear PEGs at equivalent hydrodynamic radius. In water alone, the star polymers and their linear homologues have a similar diffusion behavior in the dilute regime, as demonstrated by the similar concentration dependence of the self-diffusion coefficients. In the semidilute regime, the star polymers tend to aggregate due to their amphiphilic properties, resulting in lower self-diffusion coefficients than those of linear PEGs. 1H NMR T1 measurements at 10-70°C revealed that the PEG arms of the star polymers are more mobile than the core, suggesting the star polymers in solution have a conformation similar to that of poly(propylene imine) dendrimers.
Original language | English (US) |
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Pages (from-to) | 2345-2350 |
Number of pages | 6 |
Journal | Polymer |
Volume | 51 |
Issue number | 11 |
DOIs | |
State | Published - May 2010 |
Externally published | Yes |
Keywords
- Diffusion
- NMR spectroscopy
- Star polymers
ASJC Scopus subject areas
- Organic Chemistry
- Polymers and Plastics