Synthesis and 'schizophrenic' micellization of double hydrophilic AB 4 miktoarm star and AB diblock copolymers: Structure and kinetics of micellization

Zhishen Ge; Yuanli Cai; Jun Yin; Zhiyuan Zhu; Jingyi Rao; Shiyong Liu

doi:10.1021/la062719b

Synthesis and 'schizophrenic' micellization of double hydrophilic AB ₄ miktoarm star and AB diblock copolymers: Structure and kinetics of micellization

Zhishen Ge, Yuanli Cai, Jun Yin, Zhiyuan Zhu, Jingyi Rao, Shiyong Liu

Research output: Contribution to journal › Article › peer-review

126 Citations (Scopus)

Abstract

Poly(N-isopropylacrylamide) (PNIPAM)-based tetrafunctional atom transfer radical polymerization (ATRP) macroinitiator (1b) was synthesized via addition reaction of mono-amino-terminated PNIPAM (1a) with glycidol, followed by esterification with excess 2-bromoisobutyryl bromide. Well-defined double hydrophilic miktoarm AB₄ star copolymer, PNIPAM-b-(PDEA)₄, was then synthesized by polymerizing 2-(diethylamino)ethyl methacrylate (DEA) via ATRP in 2-propanol at 45°C using 1b, where PDEA was poly(2- (diethylamino)ethyl methacrylate). For comparison, PNIPAM-b-PDEA linear diblock copolymer with comparable molecular weight and composition to that of PNIPAM-b-(PDEA)₄ was prepared via reversible addition - fragmentation chain transfer (RAFT) polymerization. The pH- and thermoresponsive 'schizophrenic' micellization behavior of the obtained PNIPAM ₆₅-b-(PDEA₆₃)₄ miktoarm star and PNIPAM ₇₀-b-PDEA₂₆₀ linear diblock copolymers were investigated by ¹H NMR and laser light scattering (LLS). In acidic solution and elevated temperatures, PNIPAM-core micelles were formed; whereas at slightly alkaline conditions and room temperature, structurally inverted PDEA-core micelles were formed. The size of the PDEA-core micelles of PNIPAM ₆₅-b-(PDEA₆₃)₄ is much smaller than that of PNIPAM₇₀-b-PDEA₂₆₀. Furthermore, the pH-induced micellization kinetics of the AB₄ miktoarm star and AB block copolymers were investigated by the stopped-flow light scattering technique upon a pH jump from 4 to 10. Typical kinetic traces for the micellization of both types of copolymers can be well fitted with double-exponential functions, yielding a fast (τ₁) and a slow (τ₂) relaxation processes. τ₁ for both copolymers decreased with increasing polymer concentration. τ₂ was independent of polymer concentration for PNIPAM₆₅-b-(PDEA₆₃)₄, whereas it decreased with increasing polymer concentration for PNIPAM ₇₀-b-PDEA₂₆₀. The chain architectural effects on the micellization properties and the underlying mechanisms were discussed in detail.

Original language	English
Pages (from-to)	1114-1122
Number of pages	9
Journal	Langmuir
Volume	23
Issue number	3
DOIs	https://doi.org/10.1021/la062719b
Publication status	Published - 2007 Jan 30

ASJC Scopus subject areas

General Materials Science
Condensed Matter Physics
Surfaces and Interfaces
Spectroscopy
Electrochemistry

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@article{613c933ed0c74db6b676956ad3584633,

title = "Synthesis and 'schizophrenic' micellization of double hydrophilic AB 4 miktoarm star and AB diblock copolymers: Structure and kinetics of micellization",

abstract = "Poly(N-isopropylacrylamide) (PNIPAM)-based tetrafunctional atom transfer radical polymerization (ATRP) macroinitiator (1b) was synthesized via addition reaction of mono-amino-terminated PNIPAM (1a) with glycidol, followed by esterification with excess 2-bromoisobutyryl bromide. Well-defined double hydrophilic miktoarm AB4 star copolymer, PNIPAM-b-(PDEA)4, was then synthesized by polymerizing 2-(diethylamino)ethyl methacrylate (DEA) via ATRP in 2-propanol at 45°C using 1b, where PDEA was poly(2- (diethylamino)ethyl methacrylate). For comparison, PNIPAM-b-PDEA linear diblock copolymer with comparable molecular weight and composition to that of PNIPAM-b-(PDEA)4 was prepared via reversible addition - fragmentation chain transfer (RAFT) polymerization. The pH- and thermoresponsive 'schizophrenic' micellization behavior of the obtained PNIPAM 65-b-(PDEA63)4 miktoarm star and PNIPAM 70-b-PDEA260 linear diblock copolymers were investigated by 1H NMR and laser light scattering (LLS). In acidic solution and elevated temperatures, PNIPAM-core micelles were formed; whereas at slightly alkaline conditions and room temperature, structurally inverted PDEA-core micelles were formed. The size of the PDEA-core micelles of PNIPAM 65-b-(PDEA63)4 is much smaller than that of PNIPAM70-b-PDEA260. Furthermore, the pH-induced micellization kinetics of the AB4 miktoarm star and AB block copolymers were investigated by the stopped-flow light scattering technique upon a pH jump from 4 to 10. Typical kinetic traces for the micellization of both types of copolymers can be well fitted with double-exponential functions, yielding a fast (τ1) and a slow (τ2) relaxation processes. τ1 for both copolymers decreased with increasing polymer concentration. τ2 was independent of polymer concentration for PNIPAM65-b-(PDEA63)4, whereas it decreased with increasing polymer concentration for PNIPAM 70-b-PDEA260. The chain architectural effects on the micellization properties and the underlying mechanisms were discussed in detail.",

author = "Zhishen Ge and Yuanli Cai and Jun Yin and Zhiyuan Zhu and Jingyi Rao and Shiyong Liu",

year = "2007",

month = jan,

day = "30",

doi = "10.1021/la062719b",

language = "English",

volume = "23",

pages = "1114--1122",

journal = "Langmuir",

issn = "0743-7463",

publisher = "American Chemical Society",

number = "3",

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TY - JOUR

T1 - Synthesis and 'schizophrenic' micellization of double hydrophilic AB 4 miktoarm star and AB diblock copolymers

T2 - Structure and kinetics of micellization

AU - Ge, Zhishen

AU - Cai, Yuanli

AU - Yin, Jun

AU - Zhu, Zhiyuan

AU - Rao, Jingyi

AU - Liu, Shiyong

PY - 2007/1/30

Y1 - 2007/1/30

N2 - Poly(N-isopropylacrylamide) (PNIPAM)-based tetrafunctional atom transfer radical polymerization (ATRP) macroinitiator (1b) was synthesized via addition reaction of mono-amino-terminated PNIPAM (1a) with glycidol, followed by esterification with excess 2-bromoisobutyryl bromide. Well-defined double hydrophilic miktoarm AB4 star copolymer, PNIPAM-b-(PDEA)4, was then synthesized by polymerizing 2-(diethylamino)ethyl methacrylate (DEA) via ATRP in 2-propanol at 45°C using 1b, where PDEA was poly(2- (diethylamino)ethyl methacrylate). For comparison, PNIPAM-b-PDEA linear diblock copolymer with comparable molecular weight and composition to that of PNIPAM-b-(PDEA)4 was prepared via reversible addition - fragmentation chain transfer (RAFT) polymerization. The pH- and thermoresponsive 'schizophrenic' micellization behavior of the obtained PNIPAM 65-b-(PDEA63)4 miktoarm star and PNIPAM 70-b-PDEA260 linear diblock copolymers were investigated by 1H NMR and laser light scattering (LLS). In acidic solution and elevated temperatures, PNIPAM-core micelles were formed; whereas at slightly alkaline conditions and room temperature, structurally inverted PDEA-core micelles were formed. The size of the PDEA-core micelles of PNIPAM 65-b-(PDEA63)4 is much smaller than that of PNIPAM70-b-PDEA260. Furthermore, the pH-induced micellization kinetics of the AB4 miktoarm star and AB block copolymers were investigated by the stopped-flow light scattering technique upon a pH jump from 4 to 10. Typical kinetic traces for the micellization of both types of copolymers can be well fitted with double-exponential functions, yielding a fast (τ1) and a slow (τ2) relaxation processes. τ1 for both copolymers decreased with increasing polymer concentration. τ2 was independent of polymer concentration for PNIPAM65-b-(PDEA63)4, whereas it decreased with increasing polymer concentration for PNIPAM 70-b-PDEA260. The chain architectural effects on the micellization properties and the underlying mechanisms were discussed in detail.

AB - Poly(N-isopropylacrylamide) (PNIPAM)-based tetrafunctional atom transfer radical polymerization (ATRP) macroinitiator (1b) was synthesized via addition reaction of mono-amino-terminated PNIPAM (1a) with glycidol, followed by esterification with excess 2-bromoisobutyryl bromide. Well-defined double hydrophilic miktoarm AB4 star copolymer, PNIPAM-b-(PDEA)4, was then synthesized by polymerizing 2-(diethylamino)ethyl methacrylate (DEA) via ATRP in 2-propanol at 45°C using 1b, where PDEA was poly(2- (diethylamino)ethyl methacrylate). For comparison, PNIPAM-b-PDEA linear diblock copolymer with comparable molecular weight and composition to that of PNIPAM-b-(PDEA)4 was prepared via reversible addition - fragmentation chain transfer (RAFT) polymerization. The pH- and thermoresponsive 'schizophrenic' micellization behavior of the obtained PNIPAM 65-b-(PDEA63)4 miktoarm star and PNIPAM 70-b-PDEA260 linear diblock copolymers were investigated by 1H NMR and laser light scattering (LLS). In acidic solution and elevated temperatures, PNIPAM-core micelles were formed; whereas at slightly alkaline conditions and room temperature, structurally inverted PDEA-core micelles were formed. The size of the PDEA-core micelles of PNIPAM 65-b-(PDEA63)4 is much smaller than that of PNIPAM70-b-PDEA260. Furthermore, the pH-induced micellization kinetics of the AB4 miktoarm star and AB block copolymers were investigated by the stopped-flow light scattering technique upon a pH jump from 4 to 10. Typical kinetic traces for the micellization of both types of copolymers can be well fitted with double-exponential functions, yielding a fast (τ1) and a slow (τ2) relaxation processes. τ1 for both copolymers decreased with increasing polymer concentration. τ2 was independent of polymer concentration for PNIPAM65-b-(PDEA63)4, whereas it decreased with increasing polymer concentration for PNIPAM 70-b-PDEA260. The chain architectural effects on the micellization properties and the underlying mechanisms were discussed in detail.

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Synthesis and 'schizophrenic' micellization of double hydrophilic AB ₄ miktoarm star and AB diblock copolymers: Structure and kinetics of micellization

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