Macroinitiator For Atom Transfer Radical Polymerization Research Articles

Synthesis and characterization of amphiphilic and hydrophobic ABA-type tri-block copolymers using telechelic polyurethane as atom transfer radical polymerization macroinitiator

Atom transfer radical polymerization of 2-(dimethylamino) ethylmethacrylate and styrene was carried out using tertiary bromine-terminated telechelic polyurethane as a macroinitiator. The resulting ABA-type amphiphilic, poly (2-(dimethylamino) ethylmethacrylate)-b-polyurethane-b-poly (2-(dimethylamino) ethylmethacrylate) and hydrophobic, polystyrene-b-polyurethane-b-polystyrene tri-block copolymers were characterized by spectral, thermal, and chromatographic techniques. As the conversion increases, $$ {\overline M_{_{\text{n}}}} $$ also increases linearly. Theoretical M n values of the tri-block copolymers were comparable with the experimental $$ {\overline M_{_{\text{n}}}} $$ values. These results show that the polymerization of styrene and 2-(dimethylamino) ethylmethacrylate occurred through controlled radical polymerization mechanism. Mole percentage of polystyrene and poly (2-(dimethylamino) ethylmethacrylate) blocks in the tri-block copolymers was calculated using proton nuclear magnetic resonance spectroscopy, and the results were comparable with the gel permeation chromatography results. The glass transition temperatures of polystyrene and poly (2-(dimethylamino) ethylmethacrylate) blocks in the tri-block copolymers appeared at 72 °C and 110 °C, respectively. These results confirm the presence of two phases in the tri-block copolymers.

A novel amphiphilic AB2 star copolymer synthesized by the combination of ring-opening metathesis polymerization and atom transfer radical polymerization

A new amphiphilic AB2 star copolymer was synthesized by the combination of ring-opening metathesis polymerization (ROMP) and atom transfer radical polymerization (ATRP). Two different routes (methods A and B) were employed firstly to prepare the poly(oxanorbornene)-based monotelechelic polymers as the hydrophobic arm bearing dibromo-ended group via ROMP in the presence of two different terminating agents catalyzed by first generation Grubbs catalyst. The values of capping efficiency (CE) of the polymers were determined by NMR, which were 94% and 67% for methods A and B, respectively. Then, the dibromo-ended ROMP polymers were used as the macroinitiators for ATRP of 2-(dimethylamino)ethyl methacrylate (DMAEMA) to produce two hydrophilic arms. The prepared amphiphilic AB2 star copolymers poly(7-oxanorborn-5-ene-exo,exo-2,3-dicarboxylic acid dimethyl ester)-block-bis[poly(2-(dimethylamino)ethyl methacrylate)] (PONBDMn-b-(PDMAEMAm)2) with a fixed chain length of hydrophobic PONBDM and various hydrophilic PDMAEMA chain lengths can self-assemble spontaneously in water to form polymeric micelles, which were characterized by dynamic light scattering, atom force microscopy, and transmission electron microscopy measurements.

Synthesis of Brush Copolymers Based on a Poly(1,4-butadiene) Backbone via the “Grafting From” Approach by ROMP and ATRP

The synthesis of brush copolymers based on a strictly 1,4-polybutadiene (PB) backbone is reported via the “grafting from” strategy by combining two highly controlled polymerization methods: ring-opening metathesis polymerization (ROMP) and atom transfer radical polymerization (ATRP). ROMP of a cis-3,4-disubstituted cyclobutene derivative (inimer) containing two initiating sites for ATRP was first investigated with Grubb’s first-generation catalyst ((Cy3P)2RuCl2(CHPh)), leading to well-controlled polymerization for DPn up to 75. The well-defined 1,4-polybutadiene backbones obtained (Mn,SEC ranging from 3600 to 25 200 g·mol−1, PDI ≤ 1.16) were then used as macroinitiators in ATRP with styrene, methyl methacrylate, and tert-butyl acrylate. While styrene polymerization led to nonnegligible side reactions, well-defined PB-g-poly(methyl methacrylate) (Mn,SEC = 19 900−98 200 g mol−1, PDI ≤ 1.20) and PB-g-poly(tert-butyl acrylate) (Mn,SEC = 36 600−140 000 g mol−1, PDI ≤ 1.21) were obtained through this synthetic approach. In addition, the morphology of a PB-g-poly(tert-butyl acrylate) was studied through AFM measurements.

Synthesis of amphiphilic and thermoresponsive ABC miktoarm star terpolymer via a combination of consecutive click reactions and atom transfer radical polymerization

AbstractWell‐defined amphiphilic and thermoresponsive ABC miktoarm star terpolymer consisting of poly(ethylene glycol), poly(tert‐butyl methacrylate), and poly(N‐isopropylacrylamide) arms, PEG(‐b‐PtBMA)‐b‐PNIPAM, was synthesized via a combination of consecutive click reactions and atom transfer radical polymerization (ATRP). Click reaction of monoalkynyl‐terminated PEG with a trifunctional core molecule bis(2‐azidoethyl)amine, (N3)2NH, afforded difunctional PEG possessing an azido and a secondary amine moiety at the chain end, PEG‐NHN3. Next, the amidation of PEG‐NHN3 with 2‐chloropropionyl chloride led to PEG‐based ATRP macroinitiator, PEG(N3)Cl. The subsequent ATRP of N‐isopropylacrylamide (NIPAM) using PEG(N3)Cl as the macroinitiator led to PEG(N3)‐b‐PNIPAM bearing an azido moiety at the diblock junction point. Finally, well‐defined ABC miktoarm star terpolymer, PEG(‐b‐PtBMA)‐b‐PNIPAM, was prepared via the click reaction of PEG(N3)‐b‐PNIPAM with monoalkynyl‐terminated PtBMA. In aqueous solution, the obtained ABC miktoarm star terpolymer self‐assembles into micelles consisting of PtBMA cores and hybrid PEG/PNIPAM coronas, which are characterized by dynamic and static laser light scattering, and transmission electron microscopy. On heating above the phase transition temperature of PNIPAM in the hybrid corona, micelles initially formed at lower temperatures undergo further structural rearrangement and fuse into much larger aggregates solely stabilized by PEG coronas. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4001–4013, 2009

A Versatile Approach to Unimolecular Water-Soluble Carriers: ATRP of PEGMA with Hydrophobic Star-Shaped Polymeric Core Molecules as an Alternative for PEGylation

New amphiphilic star-shaped architectures with dense hydrophilic shells were synthesized by a combination of ring-opening polymerization (ROP) of ε-caprolactone (CL) and atom transfer radical polymerization (ATRP) of different poly(ethylene glycol) methacrylates (PEGMAs). The PCL hydrophobic cores with 4 and 6 arms were near-quantitatively functionalized to 4-, 6-, 8-, and 12-bromine end-capped starPCLs that were subsequently used as macroinitiators for ATRP, leading to the formation of well-defined 4-, 6-, 8-, and 12-arm starPCLpPEGMAs. The unimolecular behavior of all 4−12-arm star-shaped block copolymers was unambiguously demonstrated by dynamic light scattering (DLS) and analytical ultracentrifugation (AUC) measurements. Furthermore, no significant aggregation could be detected for the polymers loaded with different hydrophobic molecules as encapsulated guests, proving their carrier abilities in aqueous solutions. Cumulative advantages of the polyPEGMA functionalized systems, such as high hydrophilicity, tunable hydrophobic/hydrophilic balance, and molar masses, make the ATRP of PEGMA a straightforward alternative to the PEGylation approach for drug carrier systems. Furthermore, the dense PEGMA shell suppresses aggregation commonly observed for PEGylated carriers.

Synthesis of poly(ɛ-caprolactone)-block-poly(n-butyl acrylate) by combining ring-opening polymerization and atom transfer radical polymerization with Ti[OCH2CCl3]4 as difunctional initiator: I. Kinetic study of Ti[OCH2CCl3]4 initiated ring-opening polymerization of ɛ-caprolactone

A new titanium alkoxide, Ti[OCH2CCl3]4, designed to combine the ring-opening polymerization (ROP) of ɛ-caprolactone and atom transfer radical polymerization (ATRP) of n-butyl acrylate, was synthesized through the ester-exchange reaction of titanium n-propoxide and 2,2,2-trichloroethanol. The mechanism and kinetics of Ti[OCH2CCl3]4 initiated bulk polymerization of ɛ-caprolactone were studied. The results demonstrate that the polymerization proceeds through the coordination–insertion mechanism and all the four alkoxide groups in Ti[OCH2CCl3]4 share a similar activity in the initiation. The determined polymerization activation energy is 70kJ/mol. The polymerization process can be well predicted by the obtained kinetic parameters. Furthermore, PCL synthesized with Ti[OCH2CCl3]4 can be used as the macroinitiator in ATRP of n-butyl acrylate to synthesize poly(ɛ-caprolactone)-block-poly(n-butyl acrylate) (PCL-b-PBA) copolymer.

Synthesis of Miktoarm Dumbbell-Like Amphiphilic Triblock Copolymer by Combination of Consecutive RAFT Polymerizations and ATRP

A novel synthetic route, combining three reversible addition-fragmentation chain transfer (RAFT) and one atom transfer radical polymerization (ATRP) processes, for the preparation of a miktoarm dumbbell-like amphiphilic triblock copolymer, poly(poly(ethylene glycol) methyl ether methacrylate)-b-polystyrene-b-(poly(4-vinylbenzyl chloride)-g-polystyrene) (PPEGMA-b-PS-b-(PVBC-g-PS)), was developed using 2-cyanoprop-2-yl 1-dithionaphthalate (CPDN) as a RAFT agent, and the benzyl chloride group of the VBC units in the PVBC block as active ATRP macroinitiators, respectively. The structures of the obtained (co)polymers were characterized by 1H NMR spectroscopy. The obtained PPEGMA-b-PS-b-(PVBC-g-PS) amphiphilic triblock graft copolymer could self-assemble into spherical micelles with 100-300 nm diameters in a selective solvent.

Supramolecular and Biomimetic Polypseudorotaxane/Glycopolymer Biohybrids: Synthesis, Glucose-Surfaced Nanoparticles, and Recognition with Lectin

A new class of supramolecular and biomimetic glycopolymer/poly(epsilon-caprolactone)-based polypseudorotaxane/glycopolymer triblock copolymers (poly(D-gluconamidoethyl methacrylate)-PPR-poly(D-gluconamidoethyl methacrylate), PGAMA-PPR-PGAMA), exhibiting controlled molecular weights and low polydispersities, was synthesized by the combination of ring-opening polymerization of epsilon-caprolactone, supramolecular inclusion reaction, and direct atom transfer radical polymerization (ATRP) of unprotected D-gluconamidoethyl methacrylate (GAMA) glycomonomer. The PPR macroinitiator for ATRP was prepared by the inclusion complexation of biodegradable poly(epsilon-caprolactone) (PCL) with alpha-cyclodextrin (alpha-CD), in which the crystalline PCL segments were included into the hydrophobic alpha-CD cavities and their crystallization was completely suppressed. Moreover, the self-assembled aggregates from these triblock copolymers have a hydrophilic glycopolymer shell and an oligosaccharide threaded polypseudorotaxane core, which changed from spherical micelles to vesicles with the decreasing weight fraction of glycopolymer segments. Furthermore, it was demonstrated that these triblock copolymers had specific biomolecular recognition with concanavalin A (Con A) in comparison with bovine serum albumin (BSA). To the best of our knowledge, this is the first report that describes the synthesis of supramolecular and biomimetic polypseudorotaxane/glycopolymer biohybrids and the fabrication of glucose-shelled and oligosaccharide-threaded polypseudorotaxane-cored aggregates. This hopefully provides a platform for targeted drug delivery and for studying the biomolecular recognition between sugar and lectin.

Preparation of well-defined polystyrene/silica hybrid nanoparticles by ATRP

Immobilization of the atom transfer radical polymerization (ATRP) macroinitiators at the silica nanoparticle surfaces was achieved through surface modification with excess toluene-2,4-diisocynate (TDI), after which the residual isocyanate groups were converted into ATRP macroinitiators. Structurally well-defined polystyrene chains were grown from the nanoparticle surfaces to yield individual particles composed of a silica core and a well-defined, densely grafted outer polystyrene by ATRP, which was initiated by the as-synthesized silica-based macroinitiator. FTIR, NMR and gel permeation chromatography (GPC) were used to characterize the polystyrene/silica hybrid particles.

FORMATION OF FLOWER-LIKE AGGREGATES FROM SELF-ASSEMBLING OF MICELLES WITH PEO SHELLS AND CROSS-LINKED POLYACRYLAMIDE CORES

Amphiphilic block copolymers, poly(ethylene oxide)-b-poly(N-acryloxysuccinimide) (PEO-b-PNAS) with various molecular weights have been successfully synthesized by atom transfer radical polymerization (ATRP) of NAS using functionalized PEO (PEO-Br) as ATRP macroinitiator. The self-assembling of the block copolymers in water, which is a good solvent for PEO and a non-solvent for PNAS, yielded spherical core-shell micelles with PNAS as core and PEO as shell. The cross-linked reaction of oxysuccinimide in PNAS chains with ethylenediamine occurred in the core of micelles, and the core cross-linked micelles were formed. The flower-like and dendritic aggregates were formed by self-assembling of the core cross-linked micelles on the glass slides or silicon wafers. Longer PNAS block in the block copolymers and higher evaporation temperature formed bigger spherical particles. The optical microscope was used to follow the formation and growth of the flower-like aggregates from the colloidal solution and the main driving forces for the self-assembling are solution fluid and interactions between PEO chains.

Well-defined core-shell structures based on silsesquioxane microgels: Grafting of polystyrene via ATRP and product characterization

Silsesquioxane microgel nanoparticles characterized by low diameters (below 30nm) and reduced polydispersity can be produced in an acid-catalyzed sol–gel process in an aqueous microemulsion. Suitable surface modification of such structures leads to macroinitiators for atom-transfer radical polymerization (ATRP). This polymerization method was applied in order to graft polystyrene chains onto the surface of the microgels. Well-defined structures exhibiting a core-shell architecture were produced with the Mw of grafted polymers ranging from 8.5 to about 30kg/mol. The products were extensively characterized with light scattering, X-ray scattering, thermal analysis (TGA/DSC) and microscopy (TEM/SEM) to obtain information on parameters characterizing polystyrene brush. Polymer-grafted nanoparticles will be used for the modification of homopolymer and block copolymer matrices.

Modification of Multiwall Carbon Nanotubes with Initiators and Macroinitiators of Atom Transfer Radical Polymerization

Functionalization on carbon nanotube (CNT) was performed through the addition reaction between the initiators of atom transfer radical polymerization (ATRP) and CNT. The ATRP initiating groups transferred to the CNT surface with this reaction. The modified CNT then served as an ATRP macroinitiator for further modification. Both linear poly(styrene) and V-shaped poly(styrene-b-N-isopropylacrylamide) block copolymers were therefore covalently bound to the CNT surface. Characterization on the functionalized CNTs was performed with FTIR, Raman spectroscopy, and an X-ray photoelectron spectrophotometer (XPS). The functionalized CNTs exhibited good solubility in organic solvents. In addition, amphiphilic and temperature-responsive properties were observed with the CNTs functionalized with poly(styrene-b-N-isopropylacrylamide).

Fluorinated bio‐acceptable polymers via an ATRP macroinitiator approach

AbstractPolymers derived from bio‐acceptable poly(methyl methacrylate) (PMMA), poly(2‐methoxyethyl acrylate) (PMEA), and poly(oligo(ethylene glycol) methyl ether methacrylate) (PPEGMA) have been prepared via atom transfer radical polymerization (ATRP) utilizing an initiator prepared from a fluoroalkoxy‐terminated oligoethylene glycol. Polymerizations are controlled as seen by both linear first‐order kinetics and molecular weight evolution coupled with low polydispersities (<1.25) with respect to conversion. A range of ligands have been used depending upon the nature of the monomer: N‐(n‐propyl)‐2‐pyridyl‐methanimine with the methacrylates MMA and PEGMA and 1,1,4,7,10,10‐hexamethyltriethylene tetramine (HMTETA) with MEA. In all cases the use of the fluorinated initiator results in a lower apparent rate of propagation (kpapp) as compared with the more conventional and nonfluorinated initiator, ethyl 2‐bromoisobutyrate. The initiator generally also serves as an internal plasticizer lowering the glass transition temperature from the parent polymers. The surface characteristics of the fluoroinitiator containing polymers are altered compared with the nonfluorinated analogues. This is reflected in a significant increase in the advancing water contact angles of all fluoro‐containing polymers. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5770–5780, 2007

Synthesis, characterization, and micellization of an epoxy‐based amphiphilic diblock copolymer of ϵ‐caprolactone and glycidyl methacrylate by enzymatic ring‐opening polymerization and atom transfer radical polymerization

AbstractAmphiphilic diblock copolymer polycaprolactone‐block‐poly(glycidyl methacrylate) (PCL‐b‐PGMA) was synthesized via enzymatic ring‐opening polymerization (eROP) and atom transfer radical polymerization (ATRP). Methanol first initiated eROP of ϵ‐caprolactone (ϵ‐CL) in the presence of biocatalyst Novozyme‐435 under anhydrous conditions. The resulting monohydroxyl‐terminated polycaprolactone (PCL–OH) was subsequently converted to a bromine‐ended macroinitiator (PCL–Br) for ATRP by esterification with α‐bromopropionyl bromide. PCL‐b‐PGMA diblock copolymers were synthesized in a subsequent ATRP of glycidyl methacrylate (GMA). A kinetic analysis of ATRP indicated a living/controlled radical process. The macromolecular structures were characterized for PCL–OH, PCL–Br, and the block copolymers by means of nuclear magnetic resonance, gel permeation chromatography, and infrared spectroscopy. Differential scanning calorimetry and wide‐angle X‐ray diffraction analyses indicated that the copolymer composition (ϵ‐CL/GMA) had a great influence on the thermal properties. The well‐defined, amphiphilic diblock copolymer PCL‐b‐PGMA self‐assembled into nanoscale micelles in aqueous solutions, as investigated by dynamic light scattering and transmission electron microscopy. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5037–5049, 2007

Synthesis of AB 2 miktoarm star-shaped copolymers by combining stable free radical polymerization and atom transfer radical polymerization

A stable nitroxyl radical functionalized with two initiating groups for atom transfer radical polymerization (ATRP), 4-(2,2-bis-(methyl 2-bromo isobutyrate)-propionyloxy)-2,2,6,6-tetramethyl-1-piperidinyloxy (Br 2-TEMPO), was synthesized by reacting 4-hydroxyl-2,2,6,6-tetramethyl-1-piperidinyloxy with 2,2-bis-(methyl 2-bromo isobutyrate) propanoic acid. Stable free radical polymerization of styrene was then carried out using a conventional thermal initiator, dibenzoyl peroxide, along with Br 2-TEMPO. The obtained polystyrene had two active bromine atoms for ATRP at the ω-end of the chain and was further used as the macroinitiator for ATRP of methyl acrylate and ethyl acrylate to prepare AB 2-type miktoarm star-shaped copolymers. The molecular weights of the resulting miktoarm star-shaped copolymers at different monomer conversions shifted to higher molecular weights without any trace of the macroinitiator, and increased with monomer conversion.

Controlled grafting of acetylated starch by atom transfer radical polymerization of MMA

Graft copolymers of acetylated starch oligomer (AS) and poly(methyl methacrylate) (PMMA) were polymerized by atom transfer radical polymerization (ATRP). AS was converted to an ATRP macroinitiator by converting a part of the hydroxyl groups of AS to 2-bromoisobutyryl groups. Macroinitiators with varying degrees of substitution for the 2-bromoisobutyryl group were prepared. The polymerizations were conducted using CuBr/BiPy catalyst system, either in bulk or in 1:1 v/v THF solution. They proceeded with first-order kinetics and the molecular weights of the polymers increased linearly with conversion. Graft copolymers with different graft densities and graft lengths were prepared in a controlled manner. The hydrophobicity of these copolymers was studied by contact angle measurements.

Atom transfer radical polymerization of 2-methoxy ethyl acrylate and its block copolymerization with acrylonitrile

2-Methoxy ethyl acrylate (MEA), a functional monomer was homopolymerized using atom transfer radical polymerization (ATRP) technique with methyl 2-bromopropionate (MBP) as initiator and CuBr/ N, N, N′, N′, N″-pentamethyldiethylenetriamine (PMDETA) as catalyst system; polymerization was conducted in bulk at 60 °C and livingness was established by chain extension reaction. The kinetics as well as molecular weight distribution data indicated towards the controlled nature of polymerization. The initiator efficiency and the effect of initiator concentration on the rate of polymerization were investigated. The polymerization remained well-controlled even at low catalyst concentration of 10% relative to initiator. The influence of different solvents, viz. ethylene carbonate and toluene on the polymerization was investigated. End-group analysis for the determination of high degree of functionality of PMEA was determined with the help of 13C{ 1H} NMR spectra. Chain extension experiment was conducted with PMEA macroinitiator for ATRP of acrylonitrile (AN) in ethylene carbonate at 70 °C using CuCl/bpy as catalyst system. The composition of individual blocks in PMEA- b-PAN copolymers was determined using 1H NMR spectra.

Synthesis of densely grafted comblike copolymers

Densely grafted copolymers were synthesized using the grafting from approach via the combination of reversible addition-fragment chain transfer polymerization (RAFT) and atom transfer radical polymerization (ATRP). First, a novel functional monomer, 2,3-di(2-bromoisobutyryloxy)ethyl acrylate (DBPPA), with two initiating groups for ATRP was synthesized. It was then polymerized via RAFT polymerization to give macroinitiators for ATRP with controlled molecular weights and narrow molecular weight distributions. Last, ATRP of styrene was carried out using poly(DBPPA)s as macroinitiators to prepare comblike poly(DBPPA)-graft-polystyrenes carrying double branches in each repeating unit of backbone via grafting from approach. Furthermore, poly(DBPPA)-graft-[polystyrene-block-poly(t-BA)]s and their hydrolyzed products poly(DBPPA)-graft-[polystyrene-block-poly(acrylic acid)]s were also successfully prepared.

Synthesis and characterization of pH/temperature-sensitive block copolymers via atom transfer radical polymerization

In order to prepare well-defined pH-sensitive block copolymers with a narrow molecular weight distribution (MWD), we synthesized a pH-sensitive block copolymer via atom transfer radical polymerization (ATRP) of sulfamethazine methacrylate monomer (SM) and amphiphilic diblock copolymers by the ring-opening polymerization of d, l-lactide/ ɛ-caprolactone (LA/CL), and their sol–gel phase transition was investigated. SM, which is a derivative of sulfonamide, was used as a pH responsive moiety, while PCLA–PEG–PCLA was used as a biodegradable, as well as a temperature sensitive one, amphiphilic triblock copolymer. The pentablock copolymer, OSM–PCLA–PEG–PCLA–OSM, was synthesized using Br–PCLA–PEG–PCLA-Br as an ATRP macroinitiator. The number average molecular weights of SM were controlled by adjusting the monomer/initiator feed ratio. The macroinitiator was synthesized by the coupling of 2-bromoisobutyryl bromide with PCLA–PEG–PCLA in the presence of triethyl amine catalyst in dichloromethane. The resultant block copolymer shows a narrow polydispersity. The block copolymer solution shows a sol–gel transition in response to a slight pH change in the range of 7.2–8.0. Gel permeation chromatography (GPC) and NMR were used for the characterization of the polymers that were synthesized.

UV Irradiation-Induced Shell Cross-Linked Micelles with pH-Responsive Cores Using ABC Triblock Copolymers

A triblock copolymer, poly(ethylene glycol)-b-poly(glycerol monomethacrylate)-b-poly(2-(diethylamino)ethyl methacrylate) (PEG−PGMA−PDEA), was synthesized via atom transfer radical polymerization (ATRP) by successive polymerization of glycerol monomethacrylate (GMA) and 2-(diethylamino)ethyl methacrylate (DEA) using a PEG-based ATRP macroinitiator. Reacting the obtained triblock copolymer with varying amounts of cinnamoyl chloride in anhydrous pyridine yielded PEG−(PCGMA-co-PGMA)−PDEA triblock copolymer with photo-cross-linkable moieties, where PCGMA is poly(3-cinnamoyl glycerol monomethacrylate) and the mean degree of cinnamoylation ranges from 5 to 50 mol % relative to the PGMA block. All PEG−(PCGMA-co-PGMA)−PDEA triblock copolymers molecularly dissolve in aqueous media at acidic pH; upon addition of NaOH, micellization occurred above pH 7−8 to form three-layer “onionlike” micelles comprising PDEA cores, PCGMA-co-PGMA inner shells, and PEG outer coronas. The pH-induced micellization kinetics of PEG113−(C...