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Title: Effect of Corona Block Length on the Structure and Chain Exchange Kinetics of Block Copolymer Micelles

Journal Article · · Macromolecules

The effect of corona block length on micelle structure and molecular chain exchange kinetics has been investigated for a series of dilute poly(styrene)-b-poly(ethylene-alt-propylene) (SEP) diblock copolymer micelles with constant PS core block length ($$\langle$$Ncore$$\rangle$$ ≈ 255) but different PEP corona block lengths (($$\langle$$Ncorona$$\rangle$$ = 256–2080), using a combination of dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), and time-resolved small-angle neutron scattering (TR-SANS). Smaller core radii and aggregation numbers, but significantly thicker corona layers (proportional to Ncorona0.7), were observed with increasing corona block length. Furthermore, 2 orders of magnitude more rapid chain exchange was observed in SEP micelles with the longest corona block compared to the shortest. This effect is attributed to the entropic gain arising from the relief of corona chain stretching upon chain expulsion. We further extend a previous theoretical model by explicitly including a corona term associated with the entropy change in the chain exchange process, which successfully explains the influence of the corona blocks on chain exchange. Our results are in excellent agreement with simulation results of Li and Dormidontova but are apparently contradictory with Halperin and Alexander’s theory for hairy micelles and with experimental observations in two other systems that the exchange kinetics slow down with increasing corona block length. These discrepancies reveal unanticipated complexity regarding the role of the corona block in chain exchange.

Research Organization:
Argonne National Laboratory (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
OSTI ID:
1455243
Journal Information:
Macromolecules, Vol. 51, Issue 10; ISSN 0024-9297
Publisher:
American Chemical SocietyCopyright Statement
Country of Publication:
United States
Language:
ENGLISH
Citation Metrics:
Cited by: 28 works
Citation information provided by
Web of Science

References (40)

Block copolymer micelles for drug delivery: design, characterization and biological significance journal March 2001
Enhanced Performance of Blended Polymer Excipients in Delivering a Hydrophobic Drug through the Synergistic Action of Micelles and HPMCAS journal March 2017
Synergistic Increase in Ionic Conductivity and Modulus of Triblock Copolymer Ion Gels journal July 2015
Printable, Degradable, and Biocompatible Ion Gels from a Renewable ABA Triblock Polyester and a Low Toxicity Ionic Liquid journal September 2017
Deformation Processes in Block Copolymer Toughened Epoxies journal May 2015
Toughening Glassy Poly(lactide) with Block Copolymer Micelles journal March 2016
Diblock Copolymer Micelles in a Dilute Solution journal June 2005
Polymeric micelles: their relaxation kinetics journal September 1989
Time-resolved SANS for the determination of unimer exchange kinetics in block copolymer micelles journal September 2001
Logarithmic Chain-Exchange Kinetics of Diblock Copolymer Micelles journal February 2006
Mechanism of Molecular Exchange in Diblock Copolymer Micelles: Hypersensitivity to Core Chain Length journal January 2010
Molecular Exchange in Ordered Diblock Copolymer Micelles journal May 2011
Addition of Corona Block Homopolymer Retards Chain Exchange in Solutions of Block Copolymer Micelles journal February 2016
Remarkable Effect of Molecular Architecture on Chain Exchange in Triblock Copolymer Micelles journal April 2015
Molecular Exchange in Diblock Copolymer Micelles: Bimodal Distribution in Core-Block Molecular Weights journal July 2012
Chain Exchange in Binary Copolymer Micelles at Equilibrium: Confirmation of the Independent Chain Hypothesis journal April 2013
Role of Interfacial Tension for the Structure of PEP−PEO Polymeric Micelles. A Combined SANS and Pendant Drop Tensiometry Investigation journal December 2004
Tuning of structure and kinetics of chain exchange in star-like PEP-PEO block copolymer micelles journal July 2004
Equilibrium Chain Exchange Kinetics of Diblock Copolymer Micelles:  Tuning and Logarithmic Relaxation journal June 2006
Unraveling the equilibrium chain exchange kinetics of polymeric micelles using small-angle neutron scattering – architectural and topological effects journal March 2007
Equilibrium Chain Exchange Kinetics of Diblock Copolymer Micelles: Effect of Morphology journal August 2011
Equilibrium exchange kinetics in n-alkyl–PEO polymeric micelles: single exponential relaxation and chain length dependence journal January 2012
Kinetics of Diblock Copolymer Micellization by Dissipative Particle Dynamics journal March 2010
Equilibrium chain exchange kinetics in block copolymer micelle solutions by dissipative particle dynamics simulations journal January 2011
Tadpole and Mixed Linear/Tadpole Micelles of Diblock Copolymers: Thermodynamics and Chain Exchange Kinetics journal February 2017
Chain exchange kinetics between linear ABA-type triblock copolymer micelles journal June 2017
Chain Exchange Kinetics of Asymmetric B 1 AB 2 Linear Triblock and AB 1 B 2 Branched Triblock Copolymers journal August 2017
Molecular Exchange Kinetics of Micelles: Corona Chain Length Dependence journal June 2016
Structure of Poly(styrene- b -ethylene- alt -propylene) Diblock Copolymer Micelles in Squalane journal October 2009
A Small-Angle Neutron and X-ray Contrast Variation Scattering Study of the Structure of Block Copolymer Micelles:  Corona Shape and Excluded Volume Interactions journal January 2003
Polymeric micelles: a star model journal November 1987
Temperature-dependent micellar structures in poly(styrene-b-isoprene) diblock copolymer solutions near the critical micelle temperature journal January 2004
Phase Behavior of Styrene−Isoprene Diblock Copolymers in Strongly Selective Solvents journal January 2002
Poly(methyl methacrylate)- block -poly( n -butyl methacrylate) Diblock Copolymer Micelles in an Ionic Liquid: Scaling of Core and Corona Size with Core Block Length journal April 2016
Chain Exchange Kinetics in Diblock Copolymer Micelles in Ionic Liquids: The Role of χ journal December 2016
Block Copolymers—Designer Soft Materials journal February 1999
Connection between Polymer Molecular Weight, Density, Chain Dimensions, and Melt Viscoelastic Properties journal August 1994
A SANS Study of the Self-Assembly in Solution of Syndiotactic Polypropylene Homopolymers, Syndiotactic Polypropylene- b lock- poly(ethylene- c o -propylene) Diblock Copolymers, and an Alternating Atactic Isotactic Multisegment Polypropylene journal September 2004
Scaling theory of supermolecular structures in block copolymer-solvent systems: 1. Model of micellar structures journal January 1989
Apparent Critical Micelle Concentrations in Block Copolymer/Ionic Liquid Solutions: Remarkably Weak Dependence on Solvophobic Block Molecular Weight journal May 2012

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