Association of Triblock Copolymers of Ethylene Oxide and Butylene Oxide in Aqueous Solution. A Study of B_nE_mB_n Copolymers

Abstract

Three oxyethylene/oxybutylene triblock copolymers of similar E-block length but different B-block lengths (B4E40B4, B5E39B5, and B7E40B7) were prepared by sequential anionic polymerization and characterized by gel permeation chromatography and NMR spectroscopy. Their association in aqueous solution was investigated by static and dynamic light scattering, and evidence was found for small molecular associates, micelles, and micelle clusters (bridged micelles). Values of the critical micelle concentrations and micellar association numbers were determined and compared with those for related diblock (EmBn) and triblock (EmBnEm) copolymers.

Effects of block architecture and composition on the association properties of poly(oxyalkylene) copolymers in aqueous solution

“…8. Mass-average association numbers (N w ), thermodynamic radii (r t ) and hydrodynamic radii (r h ) from light scattering for micelles in aqueous solutions of cyclic diblock copoly(oxyalkylene)s and their triblock precursors 104,164) . In more concentrated solution linked molecular and micellar networks (gels) can be formed.…”

Novel Thermoreversible Gelation of Biodegradable PLGA-block-PEO-block-PLGA Triblock Copolymers in Aqueous Solution

“…[5,6,14] The micellar size and distribution of the triblock copolymer PLGA 990/207 -PEO 1000 -PLGA 207/990 (polymer concentration: 3%) in water as a function of temperature were recorded by DLS ( Figure 5). Below the lower CGT, two peaks shift continuously with increasing temperature.…”

“…[1 -3] Many commercially available block copolymers, such as poly(ethylene oxide)-block-poly(propylene oxide)-blockpoly(ethylene oxide) (PEO-block-PPO-block-PEO), poly(butylene oxide)-block-poly(ethylene oxide) (PBOblock-PEO, Dow Chem), [4,5] Pluronics (BASF) or Poloxamers (ICI) [6] can undergo a temperature-induced reversible gel-sol transition upon heating or cooling of the aqueous solution. Thermoreversible block copolymers composed of PEO (A) and biodegradable polyesters (B), such as poly(l-lactic acid) (PLLA), poly(d,l-lactic acid) (PDLA), poly[(lactic acid)-co-(glycolic acid)] (PLGA) and poly[(d,l-LA)-co-(e-caprolactone)] (CL) were studied as controlled-release drug carriers for surgical implantation and wound treatment because of their nontoxicity and biocompatibility.…”

Poly(D,L‐lactic acid‐co‐glycolic acid)‐b‐poly(ethylene glycol)‐b‐poly (D,L‐lactic acid‐co‐glycolic acid) triblock copolymer and thermoreversible phase transition in water

“…The intensity autocorrelation functions were analyzed by either CONTIN method to obtain a distribution function or cumulant method to obtain an average particle size present in the samples. 5,26 When the cumulant method was used the average hydrodynamic radius (R H ) was calculated from the angular dependence of the decay constants, of the autocorrelation functions:…”

“…5,6,[27][28][29][30] The micellar topology in aqueous solution of the ABA-type triblock copolymer is characterized by the micellar size and distribution as a function of temperature measured by dynamic laser scattering (DLS). Figure 5 displays the size distribution of micelles of the 10 wt % aqueous solution of B-3 at different temperatures, which was obtained by the CONTIN analysis of the scattered intensity autocorrelation function measured at the scattering angle of 70°.…”