Single Chain Core-Shell Nanostructure

Abstract

A combination of static and dynamic laser light scattering has revealed that at temperatures higher than ϳ33 ± C a linear poly(N-isopropylacrylamide) chain grafted with poly(ethylene oxide) (PNIPAMg-PEO) in water can undergo a "coil-to-globule" transition to form a stable single chain core-shell nanostructure with the collapsed PNIPAM chain backbone as the hydrophobic core and the grafted PEO branches as the hydrophilic shell. It was also found that there still exists ϳ75% of water in the collapsed hydrophobic core which might be useful for biomedical applications because the core-shell nanostructure can be easily switched on and off by a simple temperature variation of 1-2 ± C. [S0031-9007(97)05032-1]

Self-Association of Poly[2-(β-D-glucosyloxy)ethyl Acrylate] in Water

“…4). The particles with the diameter of 200-500 nm were large aggregates, those with the diameter of 10-40 nm were micelle-like aggregates, and those around 2 nm might be individual polymer chains (27). Based on the relative intensities of the three peaks, it can be known that the amount of individual chains in the aqueous solution of PGEA-3 was small.…”

Folding and Formation of Mesoglobules in Dilute Copolymer Solutions

“…By extending the study of the folding of linear PNIPAM homopolymer chains in water, Qiu et al [67] prepared a series of amphiphilic PNIPAM-g-PEO copolymer chains by grafting different amounts of short PEO chains on the PNIPAM chain backbone as described in the Experimental Section. In cold water, both the PNIPAM chain backbone and the grafted PEO branches are hydrophilic so that PNIPAM-g-PEO copolymer is soluble in water as individual coiled chains.…”

“…It is known that the short grafted PEO chains have an average Fig. 10 Schematic of formation of a single chain core-shell nanostructure through the coil-to-globule transition of the PNIPAM-g-PEO copolymer chain backbone [67] hydrodynamic radius of ∼ 3 nm. For the PNIPAM-g-PEO copolymer chains (M w = 7.29 × 10 6 g/mol) are grafted, on average, ∼ 70 short PEO chains per PNIPAM chain backbone, its R g changes from 155 nm to 21 nm and the ratio of R g / R h decreases from 1.5 to 0.74 during the chain folding.…”

Small Angle Neutron Scattering Study of Conformation of Oligo(ethylene glycol)-Grafted Polystyrene in Dilute Solutions: Effect of the Backbone Length

“…[13][14][15] By varying the number of EG repeat unit in the side chain, the cloud point temperature (CPT) of their aqueous solutions can be controlled within the physiological range. 15 Information on the conformation properties of OEG-grafted polymers at interfaces 14,16 and in aqueous solutions under different conditions 13,[17][18][19] is required before their applications can be exploited. SANS and LS are complementary techniques, and both are important in revealing the conformation of the polymers in solutions on the length scale on the order of 10-1000 Å (SANS) and 100-10 000 Å (LS), respectively.…”