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Published August 8, 2001 | public
Journal Article

Hydrogels with Controlled, Surface Erosion Characteristics from Self-Assembly of Fluoroalkyl-Ended Poly(ethylene glycol)

Abstract

Poly(ethylene glycol) (PEG) (M_w = 6k, 10k, and 20k g/mol) terminated at both ends by hydrophobic fluoroalkyl segments (−(CH_2)_2C_nF_(2n+1), n = 6, 8, or 10) was synthesized and demonstrated to self-assemble into hydrogels with phase behavior and mechanical and erosion properties that can be systematically varied by molecular design. With increasing fluoroalkyl length relative to PEG length, the phase behavior of these polymers in aqueous solution changes from the single-phase behavior of familiar associative thickeners, to sol−gel coexistence, to precipitation. For those polymers that exhibit sol−gel coexistence, the equilibrium gel concentration (or swelling ratio of the gel phase) and the modulus of the gel phase are governed by the length of the PEG midblock, whereas the relaxation time is determined by the hydrophobe length. The erosion characteristics of these hydrogels correlate with their phase behavior. The gels of sol−gel coexisting species exhibit surface erosion in an open system with a slow dissolution rate controlled by the end-group length; in contrast, hydrogels from polymers that show single-phase behavior exhibit bulk erosion that is relatively fast. Therefore, the molecular structure of this class of polymers produces hydrogels whose mechanical and erosion properties can be tailored for desired applications. Based on the established biocompatibility of PEG, the degree to which the characteristics of the gel phases can be tailored, and the surface erosion characteristics that can be achieved, these materials might have applications in implantable drug-release depots.

Additional Information

© 2001 American Chemical Society. Received 1 May 2001. Published online 31 July 2001. Published in print 1 August 2001. This research was supported in part by a grant from NSF (CTS-9729443), a graduate fellowship from the Korean Ministry of Education (GT), and by the MRSEC Program of NSF (DMR-0080065).

Additional details

Created:
August 19, 2023
Modified:
October 26, 2023