Single-Molecule Manipulation Experiments Reveal the Onset of Excluded Volume in Poly(Ethylene Glycol)
نویسندگان
چکیده
Poly(ethylene glycol) (PEG) is an important polymer in many biotechnological applications due to its exceptional inertness and large excluded volume in water. However, the microscopic parameters describing the realpolymer structure of PEG have never before been measured, due to a lack of sensitivity in existing bulk characterization techniques. Moreover, these microscopic parameters should depend on PEG’s complex interactions with water. Here, we present single-molecule elasticity measurements on PEG and show that as the chain length increases, it transitions from a rod-like polymer to a Gaussian coil, and only becomes swollen by excluded volume past a critical molecular weight (Fig. 1). We then vary the solvent quality using chaotropic salts and observe that the microscopic parameters change in the expected manner. We identify a room-temperature theta point at which PEG behaves as an ideal polymer for any length of chain, and see poor-solvent collapse at higher salt.
منابع مشابه
Single-molecule elasticity measurements of the onset of excluded volume in poly(ethylene glycol).
A polymer must reach a certain size to exhibit significant excluded-volume interactions and adopt a swollen random-walk configuration. We show that single-molecule measurements can sense the onset of swelling by modulating the effective chain size with force: as the force is reduced from a large value, the polymer is first highly aligned, then a Gaussian coil, then finally a swollen chain, with...
متن کاملEffect of Ethylene Oxide Functional Groups in PEBA-CNT Membranes on CO2/CH4 Mixed Gas Separation
Poly (ether-block-amide) /poly (ethylene glycol)/ carbon nanotubes mixed matrix membranes have been successfully fabricated using solvent evaporation method to determine the effect of ethylene oxide groups on the performance of produced membranes. The effects of CNTs (2-8 wt%) and PEG (up to 50 wt%)were investigated in both single and mixed gas test setup in different temperature and pressure. ...
متن کاملElastic properties of poly ethylene-glycol studied by molecular dynamics stretching simulations
Ž . Ž . Unfolding and elastic properties of single poly ethylene-glycol PEG polymers were studied by molecular dynamics Ž . MD simulations. The simulations were performed in close resemblance to recent single molecule force spectroscopy experiments, and thus allowed an interpretation of these experiments at the atomic level. In agreement with these experiments, the water solvent was found to dr...
متن کاملDocetaxel-Loaded Mixed Micelles and Polymersomes Composed of Poly (caprolactone)-Poly (ethylene glycol) (PEG-PCL) and Poly (lactic acid)-Poly (ethylene glycol) (PEG-PLA): Preparation and In-Vitro Characterization
Microwave irradiation was used to synthesize PEG-PCL and PEG-PLA copolymers that are composed of biodegradable polymers including PEG, PLA, and PCL. These copolymers were used for loading docetaxel in nanoparticles. Single emulsion-solvent evaporation technique was applied for preparing the PEG-PLA and PEG-PCL mixed nanoparticles (micelles and polymersomes) with different proportions, including...
متن کامل