The cyclic amphiphilic polymers with azobenzene in main chain, cyclic azobenzene tetraethylene glycol polystyrene (cyclic-Azo-TEG-PS) with different molecular weights, were successfully synthesized by combining atom transfer radical polymerization (ATRP) and Cu (I)-catalyzed azide/alkyne cycloaddition (CuAAC). Gel permeation chromatography (GPC), proton nuclear resonance (¹H NMR), Fourier transform-infrared (FT-IR), and matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry were used to prove the complete conversion from linear polymers to cyclic ones. The thermal properties and photoisomerization behaviors of obtained cyclic polymers have been investigated by comparison with the linear analogues. The cyclic polymer displayed a higher glass transition temperature compared with the linear one, measured by differential scanning calorimetry (DSC). It was found that the trans-to-cis and cis-to-trans isomerization of cyclic polymers was both slower than that of their respective linear counterparts upon irradiation by UV/visible light. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1834–1841

Two novel cyclic azobenzenophanes (SC, RC) with functional handles have been synthesized efficiently by a Glaser coupling reaction. Through a Suzuki coupling reaction, alternating ring/linear polymers with rigid (conjugated)/flexible (unconjugated) bridges were obtained from the resultant cyclic azobenzenophanes. The optical activities of linear, cyclic, and macromolecular binaphethyl–azobenzene derivatives were investigated by UV/Vis and circular dichroism (CD) spectra and the time-dependent (TD)-DFT method. Experimental results and theoretical analyses indicated that the cyclic configurations exhibited better chiroptical features than the others, and the reverse conformation and difference of dextro-/levo-rotation of azobenzenophanes were detected by comparing linear and cyclic structures, which provides an opportunity for the optical-rotation-controlled “smart” materials systems in future.

Fullerene-based liquid crystalline materials have both the excellent optical and electrical properties of fullerene and the self-organization and external-field-responsive properties of liquid crystals (LCs). Herein, we demonstrate a new family of thermotropic [60]fullerene supramolecular LCs with hierarchical structures. The [60]fullerene dyads undergo self-organization driven by π–π interactions to form triple-layer two-dimensional (2D) fullerene crystals sandwiched between layers of alkyl chains. The lamellar packing of 2D crystals gives rise to the formation of supramolecular LCs. This design strategy should be applicable to other molecules and lead to an enlarged family of 2D crystals and supramolecular liquid crystals.

In this work, a benzenedinitrile functionalized monomer, 2-methyl-acrylic acid 6-(3,4-dicyano-phenoxy)-hexyl ester, was successfully polymerized via the reversible addition-fragmentation chain transfer method. The polymerization behavior conveyed the characteristics of “living”/controlled radical polymerization: the first-order kinetics, linear increase of number-average molecular weight with monomer conversion, narrow molecular weight distribution, and successful chain-extension experiment. The soluble Zn(II) phthalocyanine (Pc)-containing (ZnPc) polymers were achieved by post-polymerization modification of the obtained polymers. The Zn(II) phthalocyanine-functionalized polymer was characterized by FTIR, UV–vis, fluorescence, atomic absorption spectroscopy, and thermogravimetric analysis. The potential application of above ZnPc-functionalized polymer as electron donor material in bulk heterojunction organic solar cell was studied. The device with ITO/PEDOT:PSS/ZnPc-Polymer/PC₆₁BM/LiF/Al structure provided a power conversion efficiency of 0.014%, fill factor of 0.24, open circuit voltage (V_oc) of 0.21 V, and short-circuit current (J_sc) of 0.28 mA/cm². © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 691–698

In this article, the polymerization behavior has been investigated utilizing phenyl(4-vinylbenzyl)selane (PVBS) as an inimer under ultraviolet irradiation. Corresponding copolymers and homopolymers were synthesized by copolymerization PVBS with styrene and homopolymerization itself. The branching factors (g′) of these branched polymers were characterized along with the polymerization conditions. Moreover, the results showed that the obtained polymers' refractive index (RI) can be enhanced by the introducing of selenium element. The results also indicated that the RI of obtained polymers could be adjusted extendedly by changing selenium content in them. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 504–510

Well-defined copolymer of acrylonitrile (AN) and maleic anhydride (MAn) has been successfully synthesized via reversible addition-fragmentation chain transfer polymerization. The polymerization kinetics and “living”/controlled features were thoroughly studied and confirmed. The thermal properties and spinnability of the prepared copolymers were investigated via differential scanning calorimetry, thermogravimetric analyzer, and electrospinning subsequently. When PAN-co-PMAn was used as precursors, nonwoven with “crosslinked” structures was obtained during electrospinning. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 5263–5269

A stimuli-responsive amphiphilic copolymer poly(NIPAM_m-b-VBNBI_n), including N-isopropylacrylamide (NIPAM) as a thermoresponsive unit and 1-(4-vinyl benzyl)-2-naphthyl-benzimidazole (VBNBI) as a sensitive fluorophore unit, was designed and synthesized by reversible addition-fragmentation chain transfer polymerization. The aqueous solutions of the copolymers exhibited reversible fluorescent response to pH and temperature. In addition, the copolymers showed aggregation-induced fluorescence enhancement in THF/water mixture. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4459–4466

The polymerization of a 2,7-dibromocarbazole-containing functional monomer, 6-(2,7-dibromo-9H-carbazol-9-yl)hexyl methacrylate (DBCzMA), was successfully carried out via the reversible addition-fragmentation chain transfer (RAFT) technology. The polymerization behavior possessed the feature of “living”/controlled radical polymerization, for example, the first-order kinetics, the linear increase of the molecular weight of the polymer with the monomer conversion and relatively narrow molecular weight distribution (M_w/M_n ≤ 1.27). The amphiphilic copolymers, poly(DBCzMA_m-b-NIPAM_n), with different chain length of poly(DBCzMA) and poly(N-isopropylacrylamide) (PNIPAM), were successfully prepared via RAFT chain-extension reaction, using poly(DBCzMA) as the macromolecular chain transfer agent (macro-CTA) and NIPAM as the second monomer. Modification of 2,7-dibromide groups in amphiphilic copolymer poly(DBCzMA-b-NIPAM) via Suzuki coupling reaction employed 2,7-bis(4′,4′,5′,5′-tetramethyl-1′,3′,2′-dioxaborolan-2′-yl)-N−9″-heptadecanylcarbazole as the other reaction material to afford a poly(2,7-carbazole)-containing crosslinked materials. The stable and uniform core–shell fluorescent nanoparticles were successfully prepared in water. The formed fluorescent nanoparticles showed good thermoresponsive properties, which is confirmed by dynamic light scattering observation. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4021–4030

Vinyl-conjugated monomer (methyl acrylate, MA) and allyl 2-bromopropanoate (ABP)-possessing unconjugated CC and active CBr bonds were polymerized via the Cu(0)-mediated simultaneous chain- and step-growth radical polymerization at ambient temperature using Cu(0) as catalyst, N,N,N′,N″,N″-pentamethyldiethylenetriamine as ligand and dimethyl sulfoxide as solvent. The conversion was reached higher than 98% within 20 h. The obtained polymers showed block structure consisting of polyester and vinyl polymer moieties. The Cu(0)-catalyzed simultaneous chain- and step-growth radical polymerization mechanism was demonstrated by NMR, matrix-assisted laser desorption ionization time-of-flight, and GPC analyses. Furthermore, the obtained copolymers of MA and ABP were further modified with poly(N-isopropylamide) through radical thiol-ene “click” chemistry from the terminal double bond. The thermoresponsive behavior of this block copolymer was investigated. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3907–3916

The living free radical polymerizations of vinyl acetate (VAc) were successfully achieved in the presence of a novel organic selenium compound (diselenocarbonates), with 2,2′-azobisisobutyronitrile (AIBN) as the initiator. The living characteristics of the VAc polymerization were confirmed by the linear first-order kinetic plots and linear increase of molecular weights (M_n) of the polymers with monomer conversions, while keeping the relatively low molecular weight distributions. In addition, the end of the polymers contains selenium element which may be useful in biotechnological and biomedical applications. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3159–3165

A series of selenium-substituted carbonates, S,Se-dibenzyl dithioselenocarbonate (DTSC), S,Se-dibenzyl thiodiselenocarbonate (TDSC), and Se,Se-dibenzyl triselenocarbonate (TSC), were synthesized and used as mediators in radical polymerization. The results indicate that these selenium-substituted carbonates can control the polymerization of styrene (St) and methyl acrylate, as evidenced by the number-average molecular weight that increased linearly with the monomer conversion, molecular weights that agreed well with the predicted values, and successful chain extensions. The treatment of the resultant polystyrene by hydrogen peroxide generated polymers with approximately half-reduced molecular weights, and the absence of carbonate groups and vinyl double bond-terminated chain ends. The polymerization with these selenium-substituted carbonates was the same polymerization mechanism as their analogue, the widely used S,S-dibenzyl trithiocarbonate. This work provided a flexible protocol to incorporate selenium into the polymer chain backbone. Specifically, the treatment of these polymers by oxidation produced “clickable” vinyl-terminated chain ends, which provided possibilities for further functionalization, for example, via a thiol-ene click reaction. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2606–2613

An iodine-based initiator, 2-iodo-2-methylpropionitrile (CPI), was utilized for the single-electron transfer and degenerative chain transfer mediated living radical polymerization (SET-DTLRP) of methyl methacrylate (MMA) in the absence of ligand, at ambient temperature. The CPI-initiated ligand-free polymerizations manifested reasonable control over molecular weights with relatively narrow distributions (M_w/M_n ≤ 1.35). The living nature of the polymers was further confirmed by successful chain extension reaction and ¹H NMR with high chain-end fidelity (∼96%). Screening of the available solvents suggested that the controllability of this polymerization was highly dependent on the kind of solvents, wherein dimethyl sulfoxide was a better solvent for a controlled molecular weight. The proposed ligand-free SET-DTLRP initiated by CPI was intriguing since it would dramatically decrease the concentration of Cu(0) ions both in polymerization system and resultant polymer, and provided a more economical and eco-friendly reversible-deactivation radical polymerization technique. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013

A facile soap-free miniemulsion polymerization of methyl methacrylate (MMA) was successfully carried out via a reverse ATRP technique, using a water-soluble potassium persulfate (KPS) or 2,2′-azobis(2-methylpropionamidine) dihydrochloride (V-50) both as the initiator and the stabilizer, and using an oil-soluble N,N-n-butyldithiocarbamate copper (Cu(S₂CN(C₄H₉)₂)₂) as the catalyst without adding any additional ligand. Polymerization results demonstrated the “living”/controlled characteristics of ATRP and the resultant latexes showed good colloidal stability with average particle size around 300–700 nm in diameter. The monomer droplet nucleation mechanism was proposed. NMR spectroscopy and chain-extension experiments under UV light irradiation confirmed the attachment and livingness of UV light sensitive SC(S)N(C₄H₉)₂ group in the chain end.

Well-defined cyclic-polymers (cyclic-PAzoMMAs), bearing side-chain phenylazo naphthalene chromophore, were successfully synthesized by the combination of atom transfer radical polymerization (ATRP) and copper(I)-catalyzed azide/alkyne cycloaddition “click” reaction, as verified by GPC, ¹H NMR, FTIR, and MALDI-TOF mass spectrometry. The cyclic-PAzoMMA showed higher glass transition temperatures than the linear-PAzoMMA with the same molecular weight. Interestingly, the cyclic-PAzoMMA exhibited deeper modulation depth (M.D.) induced by SRG, larger value of the photoinduced birefringence, increased fluorescence emission, and longer fluorescence lifetime in comparison with its linear counterpart.

An environmentally friendly iron catalyst system was successfully developed in water for the AGET ATRP (activator generated by electron transfer for atom transfer radical polymerization) of water-soluble monomer poly(ethylene glycol) monomethyl ether methacrylate (PEGMA) for the first time. A kinetic study indicated that the polymerization was a living/controlled process in which molecular weight increased linearly with monomer conversion. A lower molecular weight distribution (/ < 1.5) was maintained. The nontoxic and biocompatible characteristics of the iron catalyst facilitate its mediated polymerization to be used in the preparation of functional polymer materials for biomedical use.

The combination of zero-valent iron (Fe(0) powder) and copper(II) bromide was used to mediate the polymerization of methyl methacrylate (MMA) or styrene (St) at 25 ° C. The results demonstrated that the solvent played an important role on the polymerization rate and molecular-weight control. The polymerization in toluene displayed a poorly controlled process with remarkably low polymerization rate. With dimethyl sulfoxide (DMSO) as solvent, the polymerization proceeded in a relatively high rate, and the number-average molecular weights were controlled especially at higher conversion. High conversions (80%) of St could be achieved with narrow molecular weight distributions in DMSO at 25 °C. It was supposed that Fe(0) played a dual role, the activator for the generation of active radical and the reducing agent for CuBr₂.

In this work, copolymerization of two functional monomers, glycidyl methacrylate (GMA) and N,N-dimethylaminoethyl methacrylate (DMAEMA), was firstly carried out via reversible addition-fragmentation chain transfer (RAFT) polymerization successfully. The copolymerization kinetics was investigated under the molar ratio of n[GMA+DMAEMA]₀/n[AIBN]₀/n[CPDN]₀=300/1/3 at 60°C. The copolymerization showed typical "living" features such as first-order polymerization kinetics, linear increase of molecular weight with monomer conversion and narrow molecular weight distribution. The reactivity ratios of GMA and DMAEMA were calculated by the extended Kelen-Tüdös linearization methods. The epoxy group of the copolymer PGMA-co-PDMAEMA remained intact under the conditions of RAFT copolymerization and could easily be post-modified by ethylenediamine. Moreover, the modified copolymer could be used as a gene carrier.

The RAFT agents RAFT-1 and RAFT-2 were used for RAFT polymerization to synthesize well-defined bimodal molecular-weight-distribution (MWD) polymers. The system showed excellent controllability and “living” characteristics toward both the higher- and lower-molecular-weight fractions. It is important that bimodal higher-molecular-weight (HMW) polymers and block copolymers with both well-controlled molecular weight (MW) and MWD could be prepared easily due to the “living” features of RAFT polymerization. The strategy realized a mixture of higher/lower-molecular-weight polymers at the molecular level but also preserved the features of living radical polymerization (LRP) of the RAFT polymerization.

In this work, Cu(0)-mediated radical copolymerization of vinyl acetate (VAc) and acrylonitrile (AN) was explored. The polymerization was carried out at 25°C with 2,2′-bipyridine as ligand and dimethyl sulfoxide as solvent. The copolymerization proceeded smoothly producing moderately controlled molecular weights at low VAc feed ratios. The high VAc feed ratios generated low polymerization rate and poorly controlled molecular weights. FTIR, ¹H NMR, and differential scanning calorimetry confirmed the successful obtaining of the copolymers. Based on ¹H NMR spectra, the reactivity ratios of VAc and AN were calculated to be 0.003 and 1.605, respectively. This work conveyed the first example for the Cu(0)-mediated radical polymerization of AN and VAc, wherein VAc cannot be homopolymerized by Cu(0)-mediated radical polymerization technique. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Well-defined bimodal molecular weight distribution (MWD) polystyrene and polystyrene-b-poly(acrylonitrile) were successfully synthesized using a pair of mono/difunctional trithiocarbonate RAFT agents 1 and 2 via one-pot RAFT polymerization. The kinetics of RAFT polymerization for styrene in bulk with a molar ratio of [St]₀:[AIBN]₀:[1]₀:[2]₀ = 1200:1:2.5:2.5 was studied at 75°C. The results indicated that the system showed excellent controllability and “living” characteristics to both higher and lower molecular weight fractions, providing an efficient and facile way to producing bimodal MWD (co)polymers with both controlled molecular weight (MW) and MWD in molecular level, and the plausible mechanism was discussed in this work. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Two novel and well-defined polymers, poly[6-(5-(diphenylamino)-2-((4-methoxyphenyl)diazenyl)phenoxy)hexyl methacrylate] (PDMMA) and poly[6-(4-((3-ethynylphenyl)diazenyl) phenoxy)hexyl methacrylate] (PDPMMA), which bear triphenylamine (TPA) incorporated to azobenzene either directly (PDMMA) or with an interval (PDPMMA) as pendant groups were successfully prepared via reversible addition-fragmentation chain transfer polymerization technique. The electrochemical behaviors of PDPMMA and PDMMA were investigated by cyclic voltammograms (CV) measurement. The hole mobilities of the polymer films were determined by fitting the J-V (current-voltage) curve into the space-charge-limited current method. The influence of photoisomerization of the azobenzene moiety on the behaviors of fluorescence emission, CV and hole mobilities of these two polymers were studied. The fluorescent emission intensities of these two polymers in CH₂Cl₂ were increased by about 100 times after UV irradiation. The oxidation peak currents (I_OX) of the PDMMA and PDPMMA in CH₂Cl₂ were increased after UV irradiation. The photoisomerization of the azobenzene moiety in PDMMA had significant effect on the electrochemical behavior, compared with that in PDPMMA. The changes of the hole mobility before and after UV irradiation were very small for both polymers. The HOMO energies (E_HOMO, HOMO: the highest occupied molecular orbital) of side chain moieties of TPA incorporated with cis-isomer and trans-isomer of azobenzene in PDMMA and PDPMMA were obtained by theoretical calculation, which are basically consistent with the experimental results. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Copper(0)-catalyzed one-pot reaction combining living radical polymerization and “click chemistry” was investigated. By precisely tuning reaction time, three novel well-defined polymers with different degree of carboxyl substitution, poly(propargyl methacrylate) (PPgMA), poly(1-(4-carboxyphenyl)-[1,2,3]triazol-4-methyl methacrylate) (PCTMMA), and poly(1-(4-carboxyphenyl)-[1,2,3]triazol-4-methyl methacrylate-co-propargyl methacrylate) (PCTMMA-co-PPgMA) were selectively obtained via Cu(0) powder/N,N,N′,N″,N″-pentamethyldiethylenetriamine (PMDETA) cocatalyzed LRP and click chemistry. In addition, gel permeation chromatography and ¹H NMR analysis in conjunction with FTIR spectroscopy elucidate that one-pot process undergoes three steps due to a pronounced rate enhancement of click reaction: (1) generating new monomer, 1-(4-carboxyphenyl)-[1,2,3]triazol-4-methyl methacrylate (CTMMA); (2) copolymerization of two monomers (CTMMA and PgMA); (3) building homopolymer PCTMMA. Surprisingly, in contrast to typical Cu(I)-catalyzed atom transfer radical polymerization (ATRP), copper(0)-catalyzed one-pot reaction showed high carboxylic acid group tolerance. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Methyl methacrylate (MMA) were successfully polymerized by atom transfer radical polymerization with activator generated by electron transfer (AGET ATRP) using copper or iron wire as the reducing agent at 90°C. Well-controlled polymerizations were demonstrated using an oxidatively stable iron(III) chloride hexahydrate (FeCl₃·6H₂O) as the catalyst, ethyl 2-bromoisobutyrate (EBiB) as the initiator, and tetrabutylammonium bromide (TBABr) or triphenylphosphine as the ligand. The polymerization rate was fast and affected by the amount of catalyst and type of reducing agents. For example, the polymerization rate of bulk AGET ATRP with a molar ratio of [MMA]₀/[EBiB]₀/[FeCl₃·6H₂O]₀/[TBABr]₀ = 500/1/0.5/1 using iron wire (the conversion reaches up to 82.2% after 80 min) as the reducing agent was faster than that using copper wire (the conversion reaches up to 86.1% after 3 h). At the same time, the experimental M_n values of the obtained poly(methyl methacrylate) were consistent with the corresponding theoretical ones, and the M_w/M_n values were narrow (∼1.3), showing the typical features of “living”/controlled radical polymerization. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

In this work, cupric oxide (CuO) or cuprous oxide (Cu₂O) was used as the catalyst for the single electron transfer-reversible addition-fragmentation chain transfer (SET-RAFT) polymerization of methyl methacrylate in the presence of ascorbic acid at 25 °C. 2-Cyanoprop-2-yl-1-dithionaphthalate (CPDN) was used as the RAFT agent. The polymerization occurred smoothly after an induction period arising from the slow activation of CuO (or Cu₂O) and the “initialization” process in RAFT polymerization. The polymerizations conveyed features of “living”/controlled radical polymerizations: linear evolution of number-average molecular weight with monomer conversion, narrow molecular weight distribution, and high retention of chain end fidelity. From the polymerization profile, it was deduced that the polymerization proceeded via a conjunct mechanism of single electron transfer-living radical polymerization (SET-LRP) and RAFT polymerization, wherein CPDN acting as the initiator for SET-LRP and chain transfer agent for RAFT polymerization. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

An azido-containing functional monomer, 11-azido-undecanoyl methacrylate, was successfully polymerized via ambient temperature single electron transfer initiation and propagation through the reversible addition–fragmentation chain transfer (SET-RAFT) method. The polymerization behavior possessed the characteristics of “living”/controlled radical polymerization. The kinetic plot was first order, and the molecular weight of the polymer increased linearly with the monomer conversion while keeping the relatively narrow molecular weight distribution (M_w/M_n ≤ 1.22). The complete retention of azido group of the resulting polymer was confirmed by ¹H NMR and FTIR analysis. Retention of chain functionality was confirmed by chain extension with methyl methacrylate to yield a diblock copolymer. Furthermore, the side-chain functionalized polymer could be prepared by one-pot/one-step technique, which is combination of SET-RAFT and “click chemistry” methods. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

For the first time, ligand-free Cu(0)-mediated polymerization of methyl methacrylate (MMA) was realized by the selection of ethyl-2-bromo-2-phenylacetate as initiator at ambient temperature. The polymerization can reach up to 90% conversion within 5 h with dimethyl sulfoxide (DMSO) as solvent, while keeping manners of the controlled radical polymerization. Extensive investigation of this system revealed that for a well-controlled Cu(0)-mediated polymerization of MMA, the initiator should be selected with the structure as alkyl 2-bromo-2-phenylacetate, and the solvent should be DMSO or N,N-dimethylformamide. The selectivity for solvents indicated a typical single-electron transfer-living radical polymerization process. Scanning for other monomers indicated that under equal conditions, the polymerizations of other alkyl (meth)acrylates were uncontrollable. Based on these results, plausible reasons were discussed. The ligand-free Cu(0)-mediated polymerization showed its superiority with economical components and needless removal of Cu species from the resultant products. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

In this work, single electron transfer-living radical polymerization (SET-LRP) was catalyzed by in situ Cu(0) generated from copper sulphate pentahydrate (CuSO₄·5H₂O) and hydrazine hydrate (N₂H₄·H₂O) at 25 °C. The polymerization occurred smoothly with moderate controllability: the polymerization rates increased by the increases of N₂H₄·H₂O, and the initiator concentration had an optimal value on the polymerization rate; the number-average molecular weights (M_n,GPC) increased with monomer conversions and polydispersities were below 1.40. The M_n,GPC deviated much from theoretical ones with about 50% polymer chain-end fidelities. Some side reactions stemming from the strong reduction performance of N₂H₄·H₂O were responsible for the mildly controlled polymerizations. This polymerization can be conducted in SET-LRP unfavorable solvents or in bulk, such as toluene and tetrahydrofuran, owing to the H₂O contained in CuSO₄·5H₂O and N₂H₄·H₂O. On account of the utilization of CuSO₄·5H₂O, an inactive Cu(II) compounds in LRP area, this work confirmed from experimental level that it was Cu(0) which acted as activator and mediator in SET-LRP. This work provided a first example of in situ Cu(0) catalyzing SET-LRP with CuSO₄·5H₂O as a copper source. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

In this work, atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) was successfully carried out at room temperature (25 °C) under ⁶⁰Co γ-irradiation environment. The polymerization proceeded smoothly with high conversion (>90%) within 7 h. The polymerizations kept the features of controlled radical polymerization: first-order kinetics, well-predetermined number-average molecular weights (M_n,GPC), and narrow molecular weight distributions (M_w/M_n < 1.25). ¹H NMR spectroscope and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry confirmed that poly(methyl methacrylate) (PMMA) chain was end-capped by the initiator moieties. The Cu(II) concentration could reduce to 20 ppm level while keeping good control over molecular weights. This is the first successful example for the ATRP of MMA under ⁶⁰Co γ-irradiation at room temperature. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

The copper(0)-catalyzed living radical polymerization of acrylonitrile (AN) was investigated using ethyl 2-bromoisobutyrate as an initiator and 2,2′-bipyridine as a ligand. The polymerization proceeded smoothly in dimethyl sulphoxide with higher than 90% conversion in 13 h at 25 °C. The polymerization kept the features of controlled radical polymerization. ¹H NMR spectra proved that the resultant polymer was end-capped by ethyl 2-bromoisobutyrate species. Such polymerization technique was also successfully introduced to conduct the copolymerization of styrene (St) and AN to obtain well-controlled copolymers of St and AN at 25 °C, in which the monomer conversion of St could reach to higher than 90%. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Three tetrafunctional bromoxanthate agents (Xanthate₃-Br, Xanthate₂-Br₂, and Xanthate-Br₃) were synthesized. Initiative atom transfer radical polymerizations (ATRP) of styrene (St) or reversible addition fragmentation chain transfer (RAFT) polymerizations of vinyl acetate (VAc) proceeded in a controlled manner in the presence of Xanthate₃-Br, Xanthate₂-Br₂, or Xanthate-Br₃, respectively. The miktoarm star-block copolymers containing polystyrene (PS) and poly(vinyl acetate) (PVAc) chains, PS_n-b-PVAc_4-n (n = 1, 2, and 3), with controlled structures were successfully prepared by successive RAFT and ATRP chain-extension experiments using VAc and St as the second monomers, respectively. The architecture of the miktoarm star-block copolymers PS_n-b-PVAc_4-n (n = 1, 2, and 3) were characterized by gel permeation chromatography and ¹H NMR spectra. Furthermore, the results of the cleavage of PS₃-b-PVAc and PVAc₂-b-PS₂ confirmed the structures of the obtained miktoarm star-block copolymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010

The living free radical polymerizations of three “less activated” monomers (LAMs), vinyl acetate, N-vinylcarbazole, and N-vinylpyrrolidone, were successfully achieved in the presence of a disulfide, isopropylxanthic disulfide (DIP), using 2,2′-azoisobutyronitrile (AIBN) as the initiator. The living behaviors of polymerizations of LAMs are evidenced by first-order kinetic plots and linear increase of molecular weights (M_ns) of the polymers with monomer conversions, while keeping the relatively low molecular weight distributions, respectively. The effects of reaction temperatures and molar ratios of components on the polymerization were also investigated in detail. The polymerization proceeded with macromolecular design via interchange of xanthate process, where xanthate formed in situ from reaction of AIBN and DIP. The architectures of the polymers obtained were characterized by GPC, ¹H NMR, UV–vis, and MALDI-TOF-MS spectra, respectively. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010

A novel amphiphilic A₃B miktoarm star copolymer poly(N-isopropylacrylamide)₃-poly(N-vinylcarbazole) ((PNIPAAM)₃(PVK)) was successfully synthesized by a combination of single-electron transfer living radical polymerization (SET-LRP) and reversible addition-fragmentation chain transfer (RAFT) polymerization. First, the well-defined three-armed poly(N-isopropylacrylamide) (PNIPAAM)₃ was prepared via SET-LRP of N-isopropylacrylamide in acetone at 25 °C using a tetrafunctional bromoxanthate iniferter (Xanthate-Br₃) as the initiator and Cu(0)/PMDETA as a catalyst system. Secondly, the target amphiphilic A₃B miktoarm star copolymer ((PNIPAAM)₃(PVK)) was prepared via RAFT polymerization of N-vinylcarbazole (NVC) employing (PNIPAAM)₃ as the macro-RAFT agent. The architecture of the amphiphilic A₃B miktoarm star copolymers were characterized by GPC, ¹H-NMR spectra. Furthermore, the fluorescence intensity of micelle increased with the temperature and had a good temperature reversibility, which was investigated by dynamic light scattering (DLS), fluorescent and UV-vis spectra. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4268–4278, 2010

Crosslinked chiral nanoparticles were successfully synthesized via reversible addition-fragmentation chain transfer (RAFT) miniemulsion polymerization of 6-O-p-vinylbenzyl-1,2:3,4-di-O-isopropylidene-D-galactopyranose (VBPG) using linear poly(VBPG) as the macro-RAFT agent. The polymerization of VBPG in the absence of crosslinker was first studied and the kinetic results showed that the molecular weights of the obtained poly(VBPG) increased linearly with the monomer conversion and was in good consistency with the corresponding theoretical ones while there remained a relative narrow polydispersity. The effect of the amount of crosslinker, divinylbenzene, on the nanoparticle size and chiral separation properties of the obtained nanoparticles were investigated in detail using four racemates ±-3-Amino-1,2-propanediol, D,L-arabinose, D,L-tartaric acid, and D,L-mandelic acid. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1324–1331, 2010

The pH-responsive amphiphilic A₂B₂ miktoarm star block copolymer, poly(acrylic acid)₂-poly(vinyl acetate)₂ [(PAA)₂(PVAc)₂], with controlled molecular weight and well-defined structure was successfully synthesized via combination of single-electron transfer-mediated living radical polymerization (SET-LRP) and reversible addition-fragmentation chain transfer (RAFT) polymerization methods. First, the precursor two-armed poly(t-butyl acrylate) (PtBA)₂ functionalized with two xanthate groups was prepared by SET-LRP of t-butyl acrylate in acetone at 25 °C using the novel tetrafunctional bromoxanthate (Xanthate₂-Br₂) as an Iniferter (initiator-transfer agent-terminator) agent. The polymerization behavior showed typical LRP natures by the first-order polymerization kinetics and the linear dependence of molecular weight of the polymer on the monomer conversion. Second, the A₂B₂ miktoarm star block copolymer (PtBA)₂(PVAc)₂ was prepared by RAFT polymerization of VAc using (PtBA-N₃)₂(Xanthate)₂ obtained as the macro-RAFT agent. Finally, the pH-sensitive A₂B₂ amphiphilic miktoarm star block copolymer poly(acrylic acid)₂-poly(vinyl acetate)₂ ((PAA)₂(PVAc)₂) was obtained by selectively cleavage of t-butyl esters of (PtBA)₂(PVAc)₂. All the miktoarm star block copolymers were characterized by GPC, ¹H-NMR, and FT-IR spectra. The self-assembly behaviors of the amphiphilic A₂B₂ miktoarm block copolymers (PAA)₂(PVAc)₂ were also investigated by transmission electron microscopy. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2009

The novel trifunctional initiator, 1-(4-methyleneoxy-2,2,6,6-tetramethylpip-eridinoxyl)-3,5-bi(bromomethyl)-2,4,6-trimethylbenzene (TEMPO-2Br), was successfully synthesized and used to prepare the miktoarm star amphiphilic poly(styrene)-(poly(N-isopropylacrylamide))₂ (PS(PNIPAAM)₂) via combination of atom transfer radical polymerization (ATRP) and nitroxide-mediated radical polymerization (NMRP) techniques. Furthermore, the star amphiphilic block copolymer, poly (styrene)-(poly(N-isopropylacrylamide-b-4-vinylpyridine))₂ (PS(PNIPAAM-b-P4VP)₂), was also prepared using PS(PNIPAAM)₂ as the macroinitiator and 4-vinylpyridine as the second monomer by ATRP method. The obtained polymers were well-defined with narrow molecular weight distributions (M_w/M_n ≤ 1.29). Meanwhile, the self-assembly behaviors of the miktoarm amphiphilic block copolymers, PS(PNIPAAM)₂ and PS(PNIPAAM-b-P4VP)₂, were also investigated. Interestingly, the aggregate morphology changed from sphere-shaped micelles (4.7 < pH < 3.0) to a mixture of spheres and rods (1.0 < pH < 3.0), and rod-shaped nanorods formed when pH value was below 1.0. The LCST of PS(PNIPAAM)₂ (pH = 7) was about 31 °C and the LCST of PS(PNIPAAM-b-P4VP)₂ was about 35 °C (pH = 3). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6304–6315, 2009

The Cu(0)-mediated single electron transfer-living radical polymerization (SET-LRP) of methyl methacrylate (MMA) using ethyl 2-bromoisobutyrate (EBiB) as an initiator with Cu(0)/N,N,N′,N′′,N′′-pentamethyldiethylenetriamine as a catalyst system in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) was studied. The polymerization showed some living features: the measured number-average molecular weight (M_n,GPC) increased with monomer conversion and produced polymers with relatively low polydispersities. The increase of HFIP concentration improved the controllability over the polymerization with increased initiation efficiency and lowered polydispersity values. ¹H NMR, MALDI-TOF-MS spectra, and chain extension reaction confirmed that the resultant polymer was end-capped by EBiB species, and the polymer can be reactivated for chain extension. In contrast, in the cases of dimethyl sulfoxide or N,N-dimethylformamide as reaction solvent, the polymerizations were uncontrolled. The different effects of the solvents on the polymerization indicated that the mechanism of SET-LRP differed from that of atom transfer radical polymerization. Moreover, HFIP also facilitated the polymerization with control over stereoregularity of the polymers. Higher concentration of HFIP and lower reaction temperature produced higher syndiotactic ratio. The syndiotactic ratio can be reached to about 0.77 at 1/1.5 (v/v) of MMA/HFIP at −18 °C. In conclusion, using HFIP as SET-LRP solvent, the dual control over the molecular weight and tacticity of PMMA was realized. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6316–6327, 2009

Ferrocene (Fe(Cp)₂) was added to a thermal initiation of reversible addition-fragmentation chain transfer (RAFT) polymerization of methyl methacrylate (MMA) with 2-cyanoprop-2-yl 1-dithionaphthalate (CPDN) as the RAFT agent at 115 °C. It was found that the polymerization was greatly promoted after the addition of Fe(Cp)₂ while retaining the characteristics of a typical RAFT polymerization. It was proposed that the formation of a redox initiation system, in which the poly(methyl methacrylate) peroxide (PMMAP) generated in situ as the oxidizer and Fe(Cp)₂ as the reducer, was possibly the reason for the interesting polymerization phenomenon. Such a redox initiation mechanism was further validated with ascorbic acid (VC) as the reducer instead of Fe(Cp)₂. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3607–3615, 2009

Two chiral amphiphilic diblock copolymers with different relative lengths of the hydrophobic and hydrophilic blocks, poly(6-O-p-vinylbenzyl-1,2:3,4-Di-O-isopropylidene-D-galactopyranose)-b-poly(N-isopropylacrylamide) or poly(VBCPG)-b-poly(NIPAAM) and poly(20-(hydroxymethyl)-pregna-1,4-dien-3-one methacrylate)-b-poly(N-isopropylacrylamide) or poly(MAC-HPD)-b-poly(NIPAAM) were synthesized via consecutive reversible addition-fragmentation chain-transfer polymerizations of VBCPG or MAC-HPD and NIPAAM. The chemical structures of these diblock copolymers were characterized by ¹H nuclear magnetic resonance spectroscopy. These amphiphilic diblock copolymers could self-assemble into micelles in aqueous solution, and the morphologies of micelles were investigated by transmission electron microscopy. By comparison with the lower critical solution temperatures (LCST) of poly(NIPAAM) homopolymer in deionized water (32 °C), a higher LCST of the chiral amphiphilic diblock copolymer (poly(VBCPG)-b-poly(NIPAAM)) was observed and the LCST increased with the relative length of the poly(VBCPG) block in the copolymer from 35 to 47 °C, respectively. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7690–7701, 2008

Fluorescence end-labeled polystyrene (PS) with heteroaromatic carbazole or indole group were prepared conveniently via reversible addition-fragmentation chain transfer (RAFT) polymerization using dithiocarbamates, ethyl 2-(9H-carbazole-9-carbonothioylthio)propanoate (ECCP) and benzyl 2-phenyl-1H-indole-1-carbodithioate (BPIC) as RAFT agents. The end functionality of obtained PS with different molecular weights was high. The steady-state and the time-resolved fluorescence techniques had been used to study the fluorescence behaviors of obtained end-labeled PS. The fluorescence of dithiocarbamates resulting PS in solid powder cannot be monitored; however, they exhibited structured absorptions and emissions in solvent DMF and the fluorescence lifetimes of PS had no obvious change with molecular weights increasing. These observations suggested that the polymer chains were possibly stretched adequately in DMF, that is, the fluorescence end group was exposed into solvent molecules and little quenching of excited state occurred upon incorporation into polymer chain. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6198–6205, 2008

A novel azo-containing dithiocarbamate, 1-phenylethyl N,N-(4-phenylazo) phenylphenyldithiocarbamate (PPADC), was successfully synthesized and used to mediate the polymerization of methyl acrylate (MA) and styrene (St). In the presence of PPADC, the reversible addition-fragmentation chain transfer (RAFT) polymerization was well controlled in the case of MA, however, the slightly ill-controlled in the case of St. Interestingly, the polymerization of St could be well-controlled when using PPADC as the initiator in the presence of CuBr/PMDETA via atom transfer radical polymerization (ATRP) technique. In the cases of RAFT polymerization of MA and ATRP of St, the kinetic plots were both of first-order, and the molecular weight of the polymer increased linearly with the monomer conversion while keeping the relatively narrow molecular weight distribution (M_w/M_n). The molecular weight of the polymer measured by gel permeation chromatographer (GPC) was also close to the theoretical value (M_n(th)). The obtained polymer was characterized by ¹H-NMR analysis, ultraviolet absorption, FTIR spectra analysis and chain-extension experiments. Furthermore, the photoresponsive behaviors of azobenzene-terminated poly(methyl acrylate) (PMA) and polystyrene (PS) were similar to PPADC. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5626–5637, 2008

The well-defined azobenzene-containing homopolymers, poly{6-(4-phenylazophenoxy)hexyl methacrylate (AHMA)} (PAHMA), were synthesized via reversible addition fragmentation chain transfer polymerization (RAFT) in anisole solution using 2-cyanoprop-2-yl 1-dithionaphthalate (CPDN) as the RAFT agent and 2,2′-azobisisobutyronitrile (AIBN) as the initiator. The first-order kinetic plot of the polymerization and the linear dependence of molecular weights of the homopolymers with the relatively low polydispersity index values (PDIs ≤ 1.25) on the monomer conversions were observed. Furthermore, the amphiphilic diblock copolymer, poly{6-(4-phenylazophenoxy)hexyl methacrylate (AHMA)}-b-poly{2-(dimethylamino)ethyl methacrylate (DMAEMA)} (PAHMA-b-PDMAEMA), was prepared with the obtained PAHMA as the macro-RAFT agent. The structures and properties of the polymers were characterized by ¹H NMR and GPC, respectively. Interestingly, the amphiphilic diblock copolymers in chloroform (CHCl₃) solution (PAHMA₂₃-b-PDMAEMA₉₇ (4 × 10⁻⁵ M, M_n(GPC) = 18,400 g/mol, PDI = 1.48) and PAHMA₂₈-b-PDMAEMA₁₁₇ (6 × 10⁻⁵ M, M_n(GPC) = 19,300 g/mol, PDI = 1.51) exhibited the intense fluorescence emission at ambient temperature. Moreover, the fluorescent intensity of PAHMA-b-PDMAEMA in CHCl₃ was sensitive to the ultraviolet irradiation at 365 nm, which increased within the first 10 min and later decreased when irradiation time was prolonged to 30 min or longer. The well distributed, self-assembled micelles composed of azobenzene-containing amphiphilic diblock copolymers, (PAHMA-b-QPDMAEMA)s (QPDMAEMA is quaternized PDMAEMA), in the mixed N,N-dimethyl formamide (DMF)/H₂O solutions were prepared. Their fluorescent intensities decreased with the increasing amount of water. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5652–5662, 2008

Crosslinked poly(4-vinylbenzyl chloride) (PVBC) nanospheres of about 160 nm were first synthesized by emulsion copolymerization of 4-vinylbenzyl chloride (VBC) in the presence of a crosslinking agent, p-divinylbenzene. Subsequent modification of the nanosphere surfaces via surface-initiated atom transfer radical polymerization of 4-vinylpyridine, using the VBC units of PVBC on the nanosphere surface as the macroinitiators, produced a well-defined and covalently tethered poly(4-vinylpyridine) (P4VP) shells of 24–27 nm in thickness. Activation of the P4VP shells in a PdCl₂ solution, followed by reactions with CO or H₂S gas, gave rise to the corresponding P4VP composite shells containing densely dispersed palladium metal or palladium sulfide nanoparticles. The chemical composition of the nanosphere surfaces at various stages of surface modification was characterized by X-ray photoelectron spectroscopy. Field emission scanning electron microscopy and transmission electron microscopy were used to characterize the morphology of the organic/inorganic hybrid nanospheres coated with palladium/P4VP shells. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2119–2131, 2008

A three-arm star azo side-chain liquid crystalline (LC) homopolymer, poly[6-(4-methoxy-4-oxy-azobenzene) hexyl methacrylate] (PMMAZO), was synthesized by atom transfer radical polymerization (ATRP) method. The polymerization of 6-(4-methoxy-4-oxy-azobenzene) hexyl methacrylate proceeded in a controlled/“living” way. A series of three-arm star LC block copolymers (PMMAZO-b-PMMA) were also synthesized. The polymers were characterized by ¹H NMR, gel permeation chromatograph, and UV–vis spectra, respectively. The both polymers of PMMAZO and copolymers of PMMAZO-b-PMMA exhibited a smetic phase and a nematic phase. As concern to the PMMAZO, the glass-transition temperature (T_g) and phase-transition temperature from the smetic to nematic phase and from the nematic to isotropic phase increased with the increase of molecular weight (M_n(GPC)) of PMMAZO. The phase transition temperature of the block copolymers, PMMAZO-b-PMMA, with the same PMMA block was similar to that of PMMAZO. However, the T_g of the PMMAZO-b-PMMA decreased at low azo content and then increased with the increasing M_n(GPC) when azo content was above 61.3%. With illumination of linearly polarized Kr⁺ laser beam at modest intensities (35 mW/cm²), significant surface relief gratings formed on PMMAZO films with different molecular weights were observed. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 777–789, 2008

A novel optically active monomer, 6-{4-[4-(1-phenyl-1H-tetrazol-5-yloxy)-phenylazo] -phenoxy}-hexyl methacrylate (PTPPHMA) bearing tetrazole and azobenzol moieties, was synthesized and polymerized by reversible addition-fragmentation chain transfer (RAFT) polymerization using 2-cyanoprop-2-yl dithiobenzoate (CPDB) as the RAFT agent and 2, 2′-azobis(isobutyronitrile) (AIBN) as the initiator. Well-defined optically active photochromic polyPTPPHMA(PPTPPHMA) was obtained. “Living”/controlled characteristics were observed in the polymerization: well-controlled molecular weights (M_ns), narrow molecular weight distributions (M_w/M_n) of the polymers and successful chain-extension of PPTPPHMA with styrene (St) as the second monomer. The photochemical interconversion between trans and cis isomers of PPTPPHMA in N,N′-dimethyl formamide (DMF) solution was explored under irradiation of ultraviolet light. The photoinduced birefringence on the thin films of PPTPPHMA was investigated. A maximum birefringence of 0.1 was obtained, and no significant change of profiles of the birefringence after several cycles of writing/erasing/rewriting sequences was observed. The surface-relief-gratings (SRGs) were induced on the polymer films by interference of Kr⁺ laser beams at 413.1 nm with 35 mW/cm² intensity, the diffraction efficiencies from SRGs were measured to be in the range of 2.0–2.5%. The atomic force microscopy (AFM) results showed the gratings produced on the surfaces of the polymer film. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 682–691, 2008

Summary: Two multifunctional iniferters, 1,4-bis-(α-N,N-diethyldithiocarbamyl-isobutyryloxy)-benzene (BDCIB) and 1,3,5-tris-(α-N,N-diethyldithiocarbamyl-isobutyryloxy)-benzene (TDCIB), were successfully synthesized and used as initiators to initiate the polymerization of styrene in the presence of a CuBr/PMDETA complex. The polymerization results demonstrated that the kinetic plots in all cases were first-order to the monomer, the molecular weight of the polymers increased linearly with the monomer conversion; meanwhile, the molecular weight distribution of the polymer was kept to a very low value (M_w/M_n ≤ 1.35). Furthermore, the measured molecular weights were very close to the calculated values, which indicated the high efficiency of the initiator for the polymerization of styrene. The effect of catalyst concentration and initiator concentration was not obvious and the influence of polymerization temperature was apparent, and the polymerization rate increased with the polymerization temperature. The results of chain-extension and ¹H NMR analysis proved that the polymer obtained was capped with diethylthiocarbamoylthiy (DC) group.

Summary: The reversible addition–fragmentation chain transfer (RAFT) random copolymerization of N-vinylcarbazole (NVC) and vinyl acetate (VAc) was carried out using s-benzyl-o-ethyl dithiocarbonate (BED) as the chain transfer agent and 2,2′-azoisobutyronitrile (AIBN) as the initiator in 1,4-dioxane solution at 70 °C. The polymerization showed the characteristics of ‘living’ free radical polymerization behaviors: first order kinetics, linear relationships between molecular weight and conversion, and narrow polydispersity of the polymers. The reactivity ratios of NVC and VAc were calculated via the Kelen–Tudos (KT) and non-linear error in variable (EVM) methods and showed as r₁ = 1.938 ± 0.191, r₂ = 0.116 ± 0.106. The thermal behavior of the copolymers with different content of NVC and VAc was investigated by DSC and TGA. The results showed that the introduction of a VAc segment into copolymer significantly reduced the T_g of the NVC homopolymers. FT-IR spectra, fluorescence spectra, and cyclic voltammetric behavior of these copolymers were also measured and compared with those of NVC homopolymers. The copolymers showed similar oxidative behavior to the NVC homopolymer. However, there was only one reductive potential peak shown for the copolymers at about 0.058 V.

Summary: A novel amphiphilic ABCBA-type pentablock copolymer with properties that are sensitive to temperature and pH, poly(2-dimethylaminoethyl methacrylate)-block-poly(2,2,2-trifluoroethyl methacrylate)-block-poly(ε-caprolactone)-block-poly(2,2,2- trifluoroethyl methacrylate)-block-poly(2-dimethylaminoethyl methacrylate) (PDMAEMA- b-PTFEMA-b-PCL-b-PTFEMA-b-PDMAEMA), was synthesized via consecutive atom transfer radical polymerizations (ATRPs). The copolymers obtained were characterized by gel permeation chromatography (GPC) and ¹H nuclear magnetic resonance (NMR) spectroscopy, respectively. The aggregation behaviors of the pentablock copolymers in aqueous solution with different pH (pH = 4.0, 7.0 and 8.5) were studied. Transmission electron microscopic images revealed that spherical micelles from self-assembly of the pentablock copolymer were prevalent in all cases. The mean diameters of these micelles increased from 34, 46, to 119 nm when the pH of the aqueous solution decreased from 8.5, 7.0, to 4.0, respectively.