Preparation of intermediary layer crosslinked micelles from a photocrosslinkable amphiphilic ABC triblock copolymer

To prepare intermediary layer crosslinked micelles, a photocrosslinkable amphiphilic ABC triblock copolymer, poly(ethylene glycol)-b-poly(2-cinnamoyloxyethyl methacrylate)-b-poly(methyl methacrylate) (PEG-PCEMA-PMMA), was synthesized and its micellar characteristics were investigated. The triblock copolymer of PEG-b-poly(2-hydroxyethyl methacrylate)-b-PMMA (PEG-PHEMA-PMMA) (M_n = 9800 g/mol, M_w/M_n = 1.33) was first polymerized by activators generated by electron transfer (AGET) atom transfer radical polymerization (ATRP) using a PEG macroinitiator in a mixed solvent of anisole/2-isopropanol (3/1 v/v). The middle block of the copolymer was then functionalized with cinnamoyl chloride. The degrees of polymerization of the PEG, PHEMA, and PMMA blocks were 113, 18 and 21, respectively. The critical micelle concentration (CMC) of the PEG-PCEMA-PMMA was 0.011 mg/mL. The PEG-PCEMA-PMMA micelles were spherically shaped with an average diameter of 43 nm. The intermediary layer of the PEG-PCEMA-PMMA micelles was crosslinked by UV irradiation. Not all of the cinnamate groups underwent photocrosslinking probably due to a lack of other cinnamate groups in their immediate vicinity. However, the degree of photocrosslinking of the intermediary layer of the PEG-PCEMA-PMMA micelles was sufficient to give excellent colloidal stability, even in different external environments.     

Synthesis and micelle formation of triblock copolymers of poly(methyl methacrylate)-b-poly(ethylene oxide)-b-poly(methyl methacrylate) in aqueous solution

Amphiphilic triblock copolymers of poly(methyl methacrylate)-b-poly(ethylene oxide)-b-poly(methyl methacrylate) (PMMA-b-PEO-b-PMMA) with well-defined structure were synthesized via atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) initiated by the PEO macroinitiator. The macroinitiator and triblock copolymer with different PMMA and/or PEO block lengths were characterized with ¹H and ¹³C NMR and gel permeation chromatography (GPC). The micelle formed by these triblock copolymers in aqueous solutions was detected by fluorescence excitation and emission spectra of pyrene probe. The critical micelle concentration (CMC) ranged from 0.0019 to 0.016 mg/mL and increased with increasing PMMA block length, while the PEO block length had less effect on the CMC. The partition constant K_v for pyrene in the micelle and in aqueous solution was about 10⁵. The triblock copolymer appeared to form the micelles with hydrophobic PMMA core and hydrophilic PEO loop chain corona. The hydrodynamic radius R_h,app of the micelle measured with dynamic light scattering (DLS) ranged from 17.3 to 24.0 nm and increased with increasing PEO block length to form thicker corona. The spherical shape of the micelle of the triblock copolymers was observed with an atomic force microscope (AFM). Increasing hydrophobic PMMA block length effectively promoted the micelle formation in aqueous solutions, but the micelles were stable even only with short PMMA blocks.     

PEG‐b‐PtBA‐b‐PHEMA well‐defined amphiphilic triblock copolymer: Synthesis,self‐assembly,and application in drug delivery

A series of well‐defined amphiphilic triblock copolymers, poly(ethylene glycol)‐b‐poly(tert‐butyl acrylate)‐b‐poly(2‐hydroxyethyl methacrylate) (PEG‐b‐PtBA‐b‐PHEMA), were synthesized via successive atom transfer radical polymerization (ATRP). ATRP of tBA was first initiated by PEG‐Br macroinitiator using CuBr/N,N,N′,N″,N′″‐pentamethyldiethylenetriamine as catalytic system to give PEG‐b‐PtBA diblock copolymer. This copolymer was then used as macroinitiator to initiate ATRP of HEMA, which afforded the target triblock copolymer, PEG‐b‐PtBA‐b‐PHEMA. The critical micelle concentrations of obtained amphiphilic triblock copolymers were determined by fluorescence spectroscopy using N‐phenyl‐1‐naphthylamine as probe. The morphology and size of formed aggregates were investigated by transmission electron microscopy and dynamic light scattering, respectively. Finally, an acid‐sensitive PEG‐b‐PtBA‐b‐P(HEMA‐CAD) prodrug via cis‐aconityl linkage between doxorubicin and hydroxyls of triblock copolymers with a high drug loading content up to 38%, was prepared to preliminarily explore the application of triblock copolymer in drug delivery. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Construction of temperature responsive hybrid crosslinked self‐assemblies based on PEG‐b‐P(MMA‐co‐MPMA)‐b‐PNIPAAm triblock copolymer: ATRP synthesis and thermoinduced association behavior

A novel amphiphilic thermosensitive poly(ethylene glycol)₄₅‐b‐poly(methyl methacrylate₄₆‐co‐3‐(trimethoxysilyl)propyl methacrylate)₂‐b‐poly(N‐isopropylacrylamide)₄₂₉ (PEG₄₅‐b‐P(MMA₄₆‐co‐MPMA₂)‐b‐PNIPAAm₄₂₉) triblock copolymer was synthesized via consecutive atom transfer radical polymerization techniques. The thermoinduced association behavior of the resulting triblock copolymers in aqueous medium was further investigated in detail by ¹H NMR, transmission electron microscopy, and dynamic light scattering. The results showed that at the temperature (25 °C) below the LCST, PEG₄₅‐b‐P(MMA₄₆‐co‐MPMA₂)‐b‐PNIPAAm₄₂₉ triblock copolymers self‐assembled into the core crosslinked micelles with the hydrophobic P(MMA‐co‐MPMA) block constructing a dense core, protected by the mixed soluble PEG and PNIPAAm chains acting as a hydrophilic shell simultaneously. With an increase in temperature, the resulting core‐shell micelles converted into a new type of micelles with the hydrophilic PEG chains stretching out from the hydrophobic core through the collapsed PNIPAAm shell. On the other hand, at the temperature (40 °C) above the LCST, such triblock copolymers formed the crosslinked vesicles with the hydrophobic PNIPAAm and P(MMA‐co‐MPMA) blocks constructing a membrane core and the soluble PEG chains building the hydrophilic lumen and the shell. On further decreasing the temperature, the resulting vesicles underwent transformation from the shrunken to the expanded status, leading to the formation of swollen vesicles with enlarged size. This study is believed to present the first formation of two types of hybrid crosslinked self‐assemblies by thermoinduced regulation. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Electroactive methacrylate‐based triblock copolymer elastomer for actuator application

A series of ABA triblock copolymers of methyl methacrylate (MMA) and dodecyl methacrylate (DMA) [poly(MMA‐b‐DMA‐b‐MMA)] (PMDM) were synthesized by Ru‐based sequential living radical polymerization. For this, DMA was first polymerized from a difunctional initiator, ethane‐1,2‐diyl bis(2‐chloro‐2‐phenylacetate) with combination of RuCl₂(PPh₃)₃ catalyst and nBu₃N additive in toluene at 80 °C. As the conversion of DMA reached over about 90%, MMA was directly added into the reaction solution to give PMDM with controlled molecular weight (M_w/M_n ≤ 1.2). These triblock copolymers showed well‐organized morphologies such as body centered cubic, hexagonal cylinder, and lamella structures both in bulk and in thin film by self‐assembly phenomenon with different poly(methyl methacrylate) (PMMA) weight fractions. Obtained PMDMs with 20–40 wt % of the PMMA segments showed excellent electroactive actuation behaviors at relatively low voltages, which was much superior compared to conventional styrene‐ethylene‐butylene‐styrene triblock copolymer systems due to its higher polarity derived from the methacrylate backbone and lower modulus. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Block copolymer mediated synthesis of amphiphilic gold nanoparticles in water and an aqueous tetrahydrofuran medium: An approach for the preparation of polymer–gold nanocomposites

The synthesis of polymer‐matrix‐compatible amphiphilic gold (Au) nanoparticles with well‐defined triblock polymer poly[2‐(N,N‐dimethylamino)ethyl methacrylate]‐b‐poly(methyl methacrylate)‐b‐poly[2‐(N,N‐dimethylamino)ethyl methacrylate] and diblock polymers poly(methyl methacrylate)‐b‐poly[2‐(N,N‐dimethylamino)ethyl methacrylate], polystyrene‐b‐poly[2‐(N,N‐dimethylamino)ethyl methacrylate], and poly(t‐butyl methacrylate)‐b‐poly[2‐(N,N‐dimethylamino)ethyl methacrylate] in water and in aqueous tetrahydrofuran (tetrahydrofuran/H₂O = 20:1 v/v) at room temperature is reported. All these amphiphilic block copolymers were synthesized with atom transfer radical polymerization. The variations of the position of the plasmon resonance band and the core diameter of such block copolymer functionalized Au particles with the variation of the surface functionality, solvent, and molecular weight of the hydrophobic and hydrophilic parts of the block copolymers were systematically studied. Different types of polymer–Au nanocomposite films [poly(methyl methacrylate)–Au, poly(t‐butyl methacrylate)–Au, polystyrene–Au, poly(vinyl alcohol)–Au, and poly(vinyl pyrrolidone)–Au] were prepared through the blending of appropriate functionalized Au nanoparticles with the respective polymer matrices {e.g., blending poly[2‐(N,N‐dimethylamino)ethyl methacrylate]‐b‐poly(methyl methacrylate)‐b‐poly[2‐(N,N‐dimethylamino)ethyl methacrylate‐stabilized Au with the poly(methyl methacrylate)matrix only}. The compatibility of specific block copolymer modified Au nanoparticles with a specific homopolymer matrix was determined by a combination of ultraviolet–visible spectroscopy, transmission electron microscopy, and differential scanning calorimetry analyses. The facile formation of polymer–Au nanocomposites with a specific block copolymer stabilized Au particle was attributed to the good compatibility of block copolymer coated Au particles with a specific polymer matrix. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1841–1854, 2006     

Synthesis,pH‐ and temperature‐induced micellization and gelation of doubly hydrophilic triblock copolymer of poly(N,N‐dimethylamino‐2‐ethylmethacrylate)‐b‐poly(ethylene glycol)‐b‐poly(N,N‐dimethylamino‐2‐ethylmethacrylate) in aqueous solutions

A doubly hydrophilic triblock copolymer of poly(N,N‐dimethylamino‐2‐ethyl methacrylate)‐b‐Poly(ethylene glycol)‐b‐poly(N,N‐dimethylamino‐2‐ethylmethacrylate) (PDMAEMA‐b‐PEG‐b‐PDMAEMA) with well‐defined structure and narrow molecular weight distribution (M_w/M_n = 1.21) was synthesized in aqueous medium via atom transfer radical polymerization (ATRP) of N,N‐dimethylamino‐2‐ethylmethacrylate (DMAEMA) initiated by the PEG macroinitiator. The macroinitiator and triblock copolymer were characterized with ¹H NMR and gel permeation chromatography (GPC). Fluorescence spectroscopy, dynamic light scattering (DSL), transmittance measurement, and rheological characterization were applied to investigate pH‐ and temperature‐induced micellization in the dilute solution of 1 mg/mL when pH > 13 and gelation in the concentrated solution of 25 wt % at pH = 14 and temperatures beyond 80 °C. The unimer of R_h = 3.7 ± 0.8 nm coexisted with micelle of R_h = 45.6 ± 6.5 nm at pH 14. Phase separation occurred in dilute aqueous solution of the triblock copolymer of 1 mg/mL at about 50 °C. Large aggregates with R_h = 300–450 nm were formed after phase separation, which became even larger as R_h = 750–1000 nm with increasing temperature. The gelation temperature determined by rheology measurement was about 80 °C at pH 14 for the 25 wt % aqueous solution of the triblock copolymer. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5869–5878, 2008     

Light and pH Dual‐Degradable Triblock Copolymer Micelles for Controlled Intracellular Drug Release

A novel amphiphilic ABA‐type triblock copolymer poly(ethylene glycol)‐b‐poly(ethanedithiol‐alt‐nitrobenzyl)‐b‐poly(ethylene glycol) (PEG‐b‐PEDNB‐b‐PEG) is successfully prepared by sequential thiol‐acrylate Michael addition polymerization in one pot. PEG‐b‐PEDNB‐b‐PEG is designed to have light‐cleavable o‐nitrobenzyl linkages and acid‐labile β‐thiopropionate linkages positioned repeatedly in the main chain of the hydrophobic block. The light and pH dual degradation of PEG‐b‐PEDNB‐b‐PEG is traced by gel permeation chromatography (GPC). Such triblock copolymer can self‐assemble into micelles, which can be used to encapsulate anticancer drug doxorubicin (DOX). Because of the different degradation chemistry of o‐nitrobenzyl linkages and β‐thiopropionate linkages, DOX can be released from the micelles by two different manners, i.e., light‐induced rapid burst release and pH‐induced slow sustained release. Confocal laser scanning microscopy (CLSM) results indicated that DOX‐loaded micelles exhibited faster drug release in A549 cells after UV irradiation. Furthermore, 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) results show that the DOX‐loaded micelles under UV light degradation exhibit better anticancer activity against A549 cells than that of the nonirradiated ones.

     

Fluorine‐containing linear block terpolymers: Synthesis and self‐assembly in solution

Linear triblock terpolymers of poly(n‐butyl methacrylate)‐b‐poly(methyl methacrylate)‐b‐poly(2‐fluoroethyl methacrylate) (PnBMA‐PMMA‐P2FEMA) were synthesized by sequential reversible addition fragmentation chain transfer (RAFT) polymerization. Kinetic studies of the homopolymerization of 2FEMA by RAFT polymerization demonstrated controllable characteristics with fairly narrow polydispersities (～1.30). The resultant PnBMA‐PMMA‐P2FEMA triblock terpolymers were characterized via ¹H NMR, ¹⁹F NMR, and gel permeation chromatography. These polymers formed micellar aggregates in a selective solvent mixture. The as‐formed micelles were analyzed using scanning electron microscopy and dynamic light scattering. It was found that these terpolymers could directly self‐organize into complex micelles in a tetrahydrofuran/methanol mixture with diameters that depended on polymer composition. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis,self‐assembly,and formation of photo‐crosslinking‐stabilized fluorescent micelles covalently containing zinc(II)‐bis(8‐hydroxyquinoline) for ABC triblock copolymer bearing cinnamoyl and 8‐hydroxyquinoline side groups

Triblock copolymers (MPEG‐b‐PCEMA‐b‐PHQHEMA) bearing cinnamoyl and 8‐hydroxyquinoline side groups with different block length are synthesized by a two‐step reversible addition fragmentation chain transfer polymerization of cinnamoyl ethyl methacrylate (CEMA) and 2‐((8‐hydroxyquinolin‐5‐yl)methoxy)ethyl methacrylate (HQHEMA), respectively. The self‐assembly of MPEG‐b‐PCEMA‐b‐PHQHEMA in mixture of THF and ethanol is investigated by varying the ratio of THF and ethanol. Spheric micelles with diameter of 63.7 nm and polydispersity of 0.128 are obtained for MPEG₁₁₃‐b‐PCEMA₁₅‐b‐PHQHEMA₁₇ in THF/ethanol with a volume ratio (v/v) of 5/5. The PCEMA inner shell of the resulted micelles is photo‐crosslinked under UV radiation to give stabilized micelles. The complex reaction of the stabilized micelles with Zn(II) is investigated under different conditions to give zinc(II)‐bis(8‐hydroxyquinoline)(Znq₂)‐containing micelles. When the complex reaction is carried out in THF/ethanol (v/v = 5/5) or THF/toluene (v/v = 6/4) with zinc acetate, fluorescent Znq₂‐containing micelles are obtained without obvious change in diameters and morphologies. The fluorescent micelles exhibit green emission with λ_max at 520 nm. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1056–1064     

Sequential synthesis of multiblock copolymers by atom transfer radical and cationic polymerization

ABCBA‐type pentablock copolymers of methyl methacrylate (MMA), styrene (S), and isobutylene (IB) were prepared by a three‐step synthesis, which included atom transfer radical polymerization (ATRP) and cationic polymerization: (1) poly(methyl methacrylate) (PMMA) with terminal chlorine atoms was prepared by ATRP initiated with an aromatic difunctional initiator bearing two trichloromethyl groups under CuCl/2,2′‐bipyridine catalysis; (2) PMMA with the same catalyst was used for ATRP of styrene, which produced a poly(S‐b‐MMA‐b‐S) triblock copolymer; and (3) IB was polymerized cationically in the presence of the aforementioned triblock copolymer and BCl₃, and this produced a poly(IB‐b‐S‐b‐MMA‐b‐S‐b‐IB) pentablock copolymer. The reaction temperature, varied from ?78 to ?25 °C, significantly affected the IB content in the product; the highest was obtained at ?25 °C. The formation of a pentablock copolymer with a narrow molecular weight distribution provided direct evidence of the presence of active chlorine at the ends of the poly(S‐b‐MMA‐b‐S) triblock copolymer, capable of the initiation of the cationic polymerization of IB in the presence of BCl₃. A differential scanning calorimetry trace of the pentablock copolymer (20.1 mol % IB) showed the glass‐transition temperatures of three segregated domains, that is, polyisobutylene (?87.4 °C), polystyrene (95.6 °C), and PMMA (103.7 °C) blocks. One glass‐transition temperature (104.5 °C) was observed for the aforementioned triblock copolymer. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6098–6108, 2004     

Synthesis of poly(N,N‐dimethylacrylamide)‐block‐poly(ethylene oxide)‐block‐poly(N,N‐dimethylacrylamide) and its application for separation of proteins by capillary zone electrophoresis

A series of well‐defined triblock copolymers, poly(N, N‐dimethylacrylamide)‐block‐poly(ethylene oxide)‐block‐poly(N, N‐dimethylacrylamide) (PDMA‐b‐PEO‐b‐PDMA) synthesized by atom transfer radical polymerization, were used as physical coatings for protein separation. A comparative study of EOF showed that the triblock copolymer presented good capillary coating ability and EOF efficient suppression. The effects of the M_r of PDMA block in PDMA‐b‐PEO‐b‐PDMA triblock copolymer and buffer pH on the separation of basic protein for CE were investigated. Moreover, the influence of the copolymer structure on separation of basic protein was studied by comparing the performance of PDMA‐b‐PEO‐b‐PDMA triblock copolymer with PEO‐b‐PDMA diblock copolymer. Furthermore, the triblock copolymer coating showed higher separation efficiency and better migration time repeatability than fused‐silica capillary when used in protein mixture separation and milk powder samples separation, respectively. The results demonstrated that the triblock copolymer coatings would have a wide application in the field of protein separation.     

Synthesis and characterization of linear ABC triblock copolymer of ethylene oxide,methyl methacrylate,and styrene

A well‐defined linear ABC triblock copolymer of ethylene oxide (EO), methyl methacrylate (MMA), and styrene (St) was prepared by sequential living anionic and photo‐induced charge transfer polymerization (CTP) using p‐aminophenol as parent compound. In the first step, the diblock copolymer of PEO‐b‐PMMA with a protected aniline end group at PEO end was prepared by initiating of phenoxo‐anion the polymerization of EO and MMA successively, then the diblock copolymer of PEO‐b‐PMMA via deprotection of aniline at PEO end constituted a binary initiation system with benzophenone (BP) by charge transfer complex mechanism to initiate the polymerization of St under UV‐irradiation. The GPC and NMR measurements support that in copolymerization, either in the first or second step, neither homopolymer nor side reactions, such as chain transfer or chain termination, was found. The effect of the concentration of PEO_a‐b‐PMMA and St, and the polarity of solvent on the polymerization rate (R_p) of CTP is discussed. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 825–833, 1999     

Incorporation of titanium dioxide particles into polymer matrix using block copolymer micelles for fabrication of high refractive and transparent organic–inorganic hybrid materials

We report a novel strategy for incorporation of titanium dioxide (TiO₂) particles into poly(methyl methacrylate) (PMMA) to exploit high refractive and transparent organic–inorganic hybrid materials. Formation of TiO₂ particles of around 20 nm was conducted within hydrophilic core of block copolymer micelles of poly(methyl methacrylate‐block‐acrylic acid) (PMMA‐b‐PAA) in toluene via sol–gel process from titanium isopropoxide and hydrochloric acid. Subsequently, incorporation of TiO₂ particles into PMMA matrix was carried out by casting toluene solution of TiO₂ precursor‐loaded copolymer micelles, prepared from PMMA₃₅₀‐b‐PAA₉₃ and the precursor of mole ratio Ti⁴⁺/carboxyl 4.0, and PMMA. Hybrid films of TiO₂/PMMA exhibited high transparency to achieve transmission over 87% at 500 nm at 30 wt % of TiO₂ content. The refractive index of resulting hybrid films at 633 nm linearly increased with TiO₂ content to attain 1.579 at 30 wt % TiO₂, which was 0.1 higher than that of PMMA. Cross‐sectional transmission electron microscope images of TiO₂/PMMA hybrid films showed existence of TiO₂ clusters less than 100 nm, which were probably formed by aggregation or agglutination of TiO₂ particles during a drying process. It was also observed that decomposition temperature of the hybrid films elevated with increasing TiO₂ content. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Amphiphilic star‐block copolymers based on a hyperbranched core: Synthesis and supramolecular self‐assembly

Novel amphiphilic star‐block copolymers, star poly(caprolactone)‐block‐poly[(2‐dimethylamino)ethyl methacrylate] and poly(caprolactone)‐block‐poly(methacrylic acid), with hyperbranched poly(2‐hydroxyethyl methacrylate) (PHEMA–OH) as a core moiety were synthesized and characterized. The star‐block copolymers were prepared by a combination of ring‐opening polymerization and atom transfer radical polymerization (ATRP). First, hyperbranched PHEMA–OH with 18 hydroxyl end groups on average was used as an initiator for the ring‐opening polymerization of ε‐caprolactone to produce PHEMA–PCL star homopolymers [PHEMA = poly(2‐hydroxyethyl methacrylate); PCL = poly(caprolactone)]. Next, the hydroxyl end groups of PHEMA–PCL were converted to 2‐bromoesters, and this gave rise to macroinitiator PHEMA–PCL–Br for ATRP. Then, 2‐dimethylaminoethyl methacrylate or tert‐butyl methacrylate was polymerized from the macroinitiators, and this afforded the star‐block copolymers PHEMA–PCL–PDMA [PDMA = poly(2‐dimethylaminoethyl methacrylate)] and PHEMA–PCL–PtBMA [PtBMA = poly(tert‐butyl methacrylate)]. Characterization by gel permeation chromatography and nuclear magnetic resonance confirmed the expected molecular structure. The hydrolysis of tert‐butyl ester groups of the poly(tert‐butyl methacrylate) blocks gave the star‐block copolymer PHEMA–PCL–PMAA [PMAA = poly(methacrylic acid)]. These amphiphilic star‐block copolymers could self‐assemble into spherical micelles, as characterized by dynamic light scattering and transmission electron microscopy. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6534–6544, 2005     

Preparation of Cross‐Linked Micelles from Glycidyl Methacrylate Based Block Copolymers and Their Usages as Nanoreactors in the Preparation of Gold Nanoparticles

This study reports the synthesis of poly(ethylene glycol)methyl ether‐block‐poly(glycidyl methacrylate) (MPEG‐b‐PGMA) diblock, and poly(ethylene glycol)methyl ether‐block‐poly(glycidyl methacrylate)‐block‐poly(methyl methacrylate) (MPEG‐b‐PGMA‐b‐PMMA) triblock copolymers via atom transfer radical polymerization and their self‐assembly behaviors in aqueous media by using acetone as cosolvent. These block copolymers formed near monodisperse core–shell micelles having cross‐linkable cores. Two types of cross‐linked micelles, namely spherical MPEG‐b‐PGMA core cross‐linked (CCL) micelles and MPEG‐b‐PGMA‐b‐PMMA interlayer cross‐linked (ILCL) micelles, were also successfully prepared from these block copolymers by using various bifunctional cross‐linkers such as hexamethylenediamine (HMDA), ethylenediamine (EDA), and 2‐aminoethanethiol (AET). Cross‐linking was successfully carried out via ring‐opening reactions of epoxy residues of hydrophobic‐cores with primary amine or thiol groups of bifunctional cross‐linkers. Finally, these cross‐linked micelles were successfully used as nanoreactors in the synthesis of gold nanoparticles (AuNPs) in aqueous media. Both CCL and ILCL micelles were found to be good stabilizers for AuNPs in aqueous media. Both CCL‐ and ILCL‐stabilized AuNP dispersions were stable for a long time without any size changes and flocculation at room temperature. These cross‐linked stabilized AuNPs exhibited good catalytic activities in the reduction of p‐nitrophenol. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 514–526.     

Synthesis of poly(di[methylamine]ethyl methacrylate)‐b‐poly(cyclohexyl methacrylate)‐b‐poly(di[methylamine]ethyl methacrylate) amphiphilic triblock copolymers by ATRP: Condensed‐phase and solution properties

The synthesis of amphiphilic triblock copolymers, poly(di[methylamine]ethyl methacrylate)‐b‐poly(cyclohexyl methacrylate)‐b‐poly(di[methylamine]ethyl methacrylate) PDMAE‐b‐PCH‐b‐PDMAE, has been performed by atom transfer radical polymerisation. Those have been obtained in a well‐controlled manner in terms of molecular weight and polydispersity index. The triblock copolymer characterisation has been made in condensed state and in solution. The existence of microphase separation has been confirmed by differential scanning calorimetry. However, the domains of both inner and outer blocks seem not to be ordered for one another from small‐angle X‐ray scattering (SAXS) measurements using synchrotron radiation. The micelle formation in dilute methanol solutions has been confirmed for all triblock copolymers by dynamic light scattering analyses. The size of these micelles has been demonstrated to be dependent on the molecular weight. Similar observations have been made in concentrate methanol solutions by using SAXS experiments, pointed also out that an increment of the intermicelle interactions is produced as the concentration increases. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 85–92, 2008     

Synthesis of a Novel ABC Triblock Copolymer with a Rigid‐Rod Block via Atom Transfer Radical Polymerization

Summary: A novel ABC triblock copolymer with a rigid‐rod block was synthesized by atom transfer radical polymerization (ATRP). First, a poly(ethylene oxide) (PEO)‐Br macroinitiator was synthesized by esterification of PEO with 2‐bromoisobutyryl bromide, which was subsequently used in the preparation of a poly(ethylene oxide)‐block‐poly(methyl methacrylate) (PEO‐b‐PMMA) diblock copolymer by ATRP. A poly(ethylene oxide)‐block‐poly(methyl methacrylate)‐block‐poly{2,5‐bis[(4‐methoxyphenyl)oxycarbonyl]styrene} (PEO‐b‐PMMA‐b‐PMPCS) triblock copolymer was then synthesized by ATRP using PEO‐b‐PMMA as a macroinitiator.

ABC triblock copolymer with a rigid‐rod block.     

Amphiphilic ABA triblock copolymer as surfactant in syntheses of microlatexes bearing cationic groups

Polystyrene microlatexes have been prepared by conventional emulsion polymerization with a novel amphiphilic water‐soluble ABA triblock copolymer, poly[2‐(dimethylamino)ethyl methacrylate]₁₅‐b‐poly(propylene oxide)₃₆‐b‐poly[2‐(dimethyl‐amino)ethyl methacrylate]₁₅ (PDMAEMA₁₅‐PPO₃₆‐PDMAEMA₁₅), as a polycationic emulsifier under acidic or neutral conditions. The ABA triblock copolymer was developed by oxyanion‐initiated polymerization in our laboratory. In this study, it acted well both as a polycationic polymeric surfactant to form block copolymeric micelles for emulsion polymerization and as a stabilizer to be anchored into the polystyrene microlatex or adsorbed onto its surface. The results obtained with various copolymer concentrations and different pH media showed that microlatex diameters decreased remarkably with increased concentration of this ABA triblock copolymeric emulsifier, but were not as much affected by the pH of media within the experimental range of 3.4–7.0. The observed difference of the particle sizes from transmission electron microscopy and dynamic light scattering measurements is discussed in terms of the effect of the absorbed surfactants and their electrical double layers. This difference has led to the formation of a cationic polyelectrolyte fringe on the surface of microspheres. The final microlatexes were characterized with respect to total conversion, particle diameter, and particle size distribution as well as colloidal stability. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3734–3742, 2002     

Synthesis,structure, and property of well‐defined polymethylene‐based diblock copolymers by a combination of living polymerization of ylides and atom transfer radical polymerization

A combination of living polymerization of ylides and atom transfer radical polymerization (ATRP) was used successfully in the design and synthesis of well‐defined polymethylene‐b‐poly(methyl methacrylate) (PM‐b‐PMMA) and polymethylene‐b‐poly(n‐butyl acrylate) (PM‐b‐Pn‐BuA). Tripolymethylene borane were firstly synthesized by living polymerization of dimethylsulfoxonium methylides and then oxidated quantitatively through trimethylamine‐N‐oxide dihydrate to provide a series of low‐polydispersity hydroxyl‐terminated polymethylenes (PM‐OHs) with different molecular weight. Subsequently, such polymers were converted into polymethylene‐based macroinitiators (PM‐MIs, M_n(GPC) = 1900–10,400 g/mol; M_w/M_n = 1.12–1.23) in ～100% conversion. ATRPs of methyl methacrylate and n‐butyl acrylate were successfully conducted using PM‐MI to produce well‐defined diblock copolymers of PM‐b‐PMMA and PM‐b‐Pn‐BuA, respectively. The GPC traces indicated the successful extension of PMMA and Pn‐BuA segment (M_n(GPC) of PM‐b‐PMMA = 3980–10,100 g/mol; M_w/M_n = 1.16–1.22; M_n of PM‐b‐Pn‐BuA = 7400–9200 g/mol; M_w/M_n = 1.14–1.18). Atomic force microscopy (AFM) was used to characterize the structures of the precipitated PM‐b‐PMMA micelles, which were formed in toluene. The blend of LDPE/PMMA was prepared with PM‐b‐PMMA as compatibilizer. The scanning electron microscopy (SEM) results showed that the compatibilization of the LDPE/PMMA was improved greatly by the incorporation of PM‐b‐PMMA. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5671–5681, 2009