RAFT‐mediated emulsion polymerization of styrene using brush copolymer as surfactant macro‐RAFT agent: Effect of the brush copolymer sequence and chemical composition

The nonionic amphiphilic brush polymers such as poly[poly(ethylene oxide) methyl ether vinylphenyl‐co‐styrene] trithiocarbonate [P(mPEGV‐co‐St)‐TTC] and poly[poly(ethylene oxide) methyl ether vinylphenyl‐b‐styrene‐b‐poly(ethylene oxide) methyl ether vinylphenyl] trithiocarbonate [P(mPEGV‐b‐St‐b‐mPEGV)‐TTC] with different monomer sequence and chemical composition are synthesized and their application as macro‐RAFT agent in the emulsion RAFT polymerization of styrene is explored. It is found that the monomer sequence in the brush polymers exerts great influence on the emulsion RAFT polymerization kinetics, and the fast polymerization with short induction period in the presence of P(mPEGV‐co‐St)‐TTC is demonstrated. Besides, the chemical composition in the brush polymer macro‐RAFT agent effect on the emulsion RAFT polymerization is investigated, and the macro‐RAFT agent with high percent of the hydrophobic PS segment leads to fast and well controlled polymerization. The growth of triblock copolymer colloids in the emulsion polymerization is checked, and it reveals that the colloidal morphology is ascribed to the hydrophobic PS block extension, and the P(mPEGV‐co‐St) block almost have no influence just on the size of the colloids. This may be the first example to study the monomer sequence and the chemical composition in the macro‐RAFT agent on emulsion RAFT polymerization, and will be useful to reveal the block copolymer particle growth. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Synthesis and characterization of well‐defined poly(2‐hydroxyethyl methacrylate‐co‐styrene)‐graft‐poly(ε‐caprolactone) by sequential controlled polymerization

A new graft copolymer, poly(2‐hydroxyethyl methacrylate‐co‐styrene) ‐graft‐poly(?‐caprolactone), was prepared by combination of reversible addition‐fragmentation chain transfer polymerization (RAFT) with coordination‐insertion ring‐opening polymerization (ROP). The copolymerization of styrene (St) and 2‐hydroxyethyl methacrylate (HEMA) was carried out at 60 °C in the presence of 2‐phenylprop‐2‐yl dithiobenzoate (PPDTB) using AIBN as initiator. The molecular weight of poly (2‐hydroxyethyl methacrylate‐co‐styrene) [poly(HEMA‐co‐St)] increased with the monomer conversion, and the molecular weight distribution was in the range of 1.09 ～ 1.39. The ring‐opening polymerization (ROP) of ?‐caprolactone was then initiated by the hydroxyl groups of the poly(HEMA‐co‐St) precursors in the presence of stannous octoate (Sn(Oct)₂). GPC and ¹H‐NMR data demonstrated the polymerization courses are under control, and nearly all hydroxyl groups took part in the initiation. The efficiency of grafting was very high. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5523–5529, 2004     

Synthesis of water‐dispersible,fluorinated particles with grafting sulfonate chains by the core crosslinking of block copolymer micelles

Fluorinated polymer particles with grafting sulfonate chains, which showed high dispersion stability in aqueous media, were synthesized by the crosslinking of block copolymer micelles. A crosslinkable block copolymer, poly[(2,3,4,5,6‐pentafluorostyrene)‐co‐4‐(1‐methylsilacyclobutyl)styrene]‐b‐poly(neopentyl 4‐styrenesulfonate), composed of a statistical copolymer segment of 2,3,4,5,6‐pentafluorostyrene with 4‐(1‐methylsilacyclobutyl)styrene and a neopentyl 4‐styrenesulfonate segment, was prepared by the nitroxy‐mediated living radical polymerization of a 2,3,4,5,6‐pentafluorostyrene/4‐(1‐methylsilacyclobutyl)styrene mixture and neopentyl 4‐styrenesulfonate. The block copolymer formed micelles with a poly[(2,3,4,5,6‐pentafluorostyrene)‐co‐4‐(1‐methylsilacyclobutyl)styrene] core in acetonitrile, which were crosslinked via the ring‐opening reaction of silacyclobutyl groups in the core by a treatment with a platinum catalyst. The deprotection of sulfonate groups in the micelle corona by exposure to trimethylsilyl iodide and a treatment with aqueous HCl, followed by neutralization with aqueous NaOH, provided a polymer particle with polymer chains of sodium 4‐styrenesulfonate grafted on its surface. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1316–1323, 2007     

Synthesis and characterization of amphiphilic block copolymers with allyl side‐groups

The synthesis of a new cyclic carbonate monomer containing an allyl group was reported and its biodegradable amphiphilic block copolymer, poly(ethylene glycol)‐block‐poly(L ‐lactide‐co‐5‐methyl‐5‐allyloxycarbonyl‐propylene carbonate) [PEG‐b‐P(LA‐co‐MAC)] was synthesized by ring‐opening polymerization (ROP) of L ‐lactide (LA) and 5‐methyl‐5‐allyloxycarbonyl‐1,3‐dioxan‐2‐one (MAC) in the presence of poly (ethylene glycol) as a macroinitiator, with diethyl zinc as a catalyst. ¹³C NMR and ¹H NMR were used for microstructure identification of the copolymers. The copolymer could form micelles in aqueous solution. The core of the micelles is built of the hydrophobic P(LA‐co‐MAC) chains, whereas the shell is set up by the hydrophilic PEG blocks. The micelles exhibited a homogeneous spherical morphology and unimodal size distribution. By using the cyclic carbonate monomer containing allyl side‐groups, crosslinking of the PEG‐b‐P(LA‐co‐MAC) inner core was possible. The adhesion and spreading of ECV‐304 cells on the copolymer were better than that on PLA films. Therefore, this biodegradable amphiphilic block copolymer is expected to be used as a biomaterial for drug delivery and tissue engineering. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5518–5528, 2007     

Synthesis and characterization of amphiphilic copolymer of linear poly(ethylene oxide) linked with [poly(styrene‐co‐2‐hydroxyethyl methacrylate)‐graft‐poly(ε‐caprolactone)] using sequential controlled polymerization

A well‐defined amphiphilic copolymer of ‐poly(ethylene oxide) (PEO) linked with comb‐shaped [poly(styrene‐co‐2‐hydeoxyethyl methacrylate)‐graft‐poly(ε‐caprolactone)] (PEO‐b‐P(St‐co‐HEMA)‐g‐PCL) was successfully synthesized by combination of reversible addition‐fragmentation chain transfer polymerization (RAFT) with ring‐opening anionic polymerization and coordination–insertion ring‐opening polymerization (ROP). The α‐methoxy poly(ethylene oxide) (mPEO) with ω,3‐benzylsulfanylthiocarbonylsufanylpropionic acid (BSPA) end group (mPEO‐BSPA) was prepared by the reaction of mPEO with 3‐benzylsulfanylthiocarbonylsufanyl propionic acid chloride (BSPAC), and the reaction efficiency was close to 100%; then the mPEO‐BSPA was used as a macro‐RAFT agent for the copolymerization of styrene (St) and 2‐hydroxyethyl methacrylate (HEMA) using 2,2‐azobisisobutyronitrile as initiator. The molecular weight of copolymer PEO‐b‐P(St‐co‐HEMA) increased with the monomer conversion, but the molecular weight distribution was a little wide. The influence of molecular weight of macro‐RAFT agent on the polymerization procedure was discussed. The ROP of ε‐caprolactone was then completed by initiation of hydroxyl groups of the PEO‐b‐P(St‐co‐HEMA) precursors in the presence of stannous octoate (Sn(Oct)₂). Thus, the amphiphilic copolymer of linear PEO linked with comb‐like P(St‐co‐HEMA)‐g‐PCL was obtained. The final and intermediate products were characterized in detail by NMR, GPC, and UV. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 467–476, 2006     

Porphyrin derivatives act as vinylene monomers in TEMPO‐mediated radical copolymerization with styrene

In this article, we offer clear evidence for the radical copolymerizability of porphyrin rings in 2,2,6,6‐tetramethyl‐1‐piperidinyloxy (TEMPO)‐mediated radical copolymerizations with styrene. The radical copolymerizations of styrene with 5,10,15,20‐tetrakis(pentafluorophenyl)porphyrin (H₂TFPP) was conducted using 1‐phenyl‐1‐(2,2,6,6‐tetramethyl‐1‐piperidinyloxy)ethane as an initiator. The refractive index (RI) traces for the size‐exclusion chromatography of the resulting copolymers were unimodal with narrow molecular weight distributions. The RI traces shifted toward higher molecular weight regions as the polymerization progressed, and the number‐average molecular weights were close to those calculated on the basis of the feed compositions and monomer conversions. These features were in good agreement with a TEMPO‐mediated mechanism. The traces recorded by the ultraviolet‐visible (UV‐vis) detector (430 nm) were identical to those obtained by the RI detector, indicating a statistical copolymerization of styrene with H₂TFPP. This also indicated that H₂TFPP acted as a monomer and not as a terminator or a chain‐transfer agent under the conditions used. A benzyl radical addition to H₂TFPP was conducted as a model reaction for the copolymerization using tributyltin hydride as a chain‐transfer agent, affording a reduced porphyrin, 2‐benzyl‐5,10,15,20‐tetrakis(pentafluorophenyl)chlorin 1 , via radical addition to the β‐pyrrole position. The UV‐vis spectrum of 1 was fairly similar to that of poly(styrene‐co‐H₂TFPP), indicating that H₂TFPP polymerized at its β‐pyrrole position in the TEMPO‐mediated radical polymerization. TEMPO‐mediated radical copolymerizations of styrene with several porphyrin derivatives were also demonstrated. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

The glucose‐responsive behavior of a block copolymer featuring boronic acid and glycine

Glucose responsive block copolymer featuring boronic acid as a glucose responsive moiety and glycine are reported. The first block is polymerized through reversible addition–fragmentation chain transfer (RAFT) polymerization and the resulting poly(N‐acryloylmorpholine)₁₁₃ (PAcM) is employed as a macro‐chain transfer agent for chain extension with pentafluorophenyl acrylate (PFPA) yielding a well‐defined PAcM₁₁₃‐block‐poly(pentafluorophenyl acrylate)₈₄ (PPFPA). The PPFPA block is then reacted with functional (3‐aminomethyl) phenyl boronic acid and glycine via post‐polymerization modification and the structure of the block copolymer is confirmed by proton nuclear magnetic resonance (NMR), ¹⁹F NMR, Fourier transform infrared, and gel permeation chromatography. By copolymerizing glycine into the polymer backbone, the relative pK_a of the block copolymer is significantly lowered. The block copolymer can self‐assemble into core–shell micelles in aqueous solution and disassemble in response to glucose at the physiological pH. Furthermore, the encapsulation and release of Nile red (NR) as a hydrophobic model drug is studied under the physiological pH. The influence of the glucose concentration on the NR release from the polymeric micelles is demonstrated. These results suggested that the glucose‐responsive poly[(AcM)₁₁₃‐b‐(3‐(aminomethyl)phenylboronic acid hydrochloride(‐co‐Gly)₈₄] block copolymer has potential applications as a glucose‐responsive polymer for insulin delivery. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 422–431     

Synthesis of amphiphilic and thermosensitive graft copolymers with fluorescence P(St‐co‐(p‐CMS))‐g‐PNIPAAM by combination of NMP and RAFT methods

A three‐step process, combining nitroxide‐mediated polymerization (NMP) and reversible addition‐fragmentation chain transfer (RAFT) polymerization techniques, for synthesizing well‐defined amphiphilic and thermosensitive graft copolymers with fluorescence poly(styrene‐co‐(p‐chloromethylstyrene))‐g‐poly(N‐isopropylacrylamide) (P(St‐co‐(p‐CMS))‐g‐PNIPAAM), was conducted. Firstly, the NMP of styrene (St) and p‐chloromethylstyrene (p‐CMS) were carried out using benzoyl peroxide (BPO) as the initiator to obtain the random copolymers of P(St‐co‐(p‐CMS)). Secondly, the random copolymers were converted into macro‐RAFT agents with fluorescent carbazole as Z‐group through a simple method. Then the macro‐RAFT agents were used in the RAFT polymerization of N‐isopropylacrylamide (NIPAAM) to prepare fluorescent amphiphilic graft copolymers P(St‐co‐(p‐CMS))‐g‐PNIPAAM with controlled molecular weights and well‐defined structures. The copolymers obtained were characterized by gel permeation chromatography (GPC), ¹H nuclear magnetic resonance (NMR) spectroscopy, and FT‐IR spectroscopy. The size of self‐assembly micelles of the resulting graft copolymers in deionized water was studied by high performance particle sizer (HPPS), the results showed that the Z‐average size of the micelles increased with the increase of molecular weights of PNIPAAM in side chains. The aqueous solution of the micelles prepared from P(St‐co‐(p‐CMS))‐g‐PNIPAAM using a dialysis method showed a lower critical solution temperature (LCST) at ～ 27.5 °C, which was below the value of NIPAAM homopolymer (32 °C). © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5318–5328, 2007     

Synthesis of amphiphilic copolymer brushes: Poly(ethylene oxide)‐graft‐polystyrene

A well‐defined amphiphilic copolymer brush with poly(ethylene oxide) as the main chain and polystyrene as the side chain was successfully prepared by a combination of anionic polymerization and atom transfer radical polymerization (ATRP). The glycidol was first protected by ethyl vinyl ether to form 2,3‐epoxypropyl‐1‐ethoxyethyl ether and then copolymerized with ethylene oxide by the initiation of a mixture of diphenylmethylpotassium and triethylene glycol to give the well‐defined polymer poly(ethylene oxide‐co‐2,3‐epoxypropyl‐1‐ethoxyethyl ether); the latter was hydrolyzed under acidic conditions, and then the recovered copolymer of ethylene oxide and glycidol {poly(ethylene oxide‐co‐glycidol) [poly(EO‐co‐Gly)]} with multiple pending hydroxymethyl groups was esterified with 2‐bromoisobutyryl bromide to produce the macro‐ATRP initiator [poly(EO‐co‐Gly)_(ATRP). The latter was used to initiate the polymerization of styrene to form the amphiphilic copolymer brushes. The object products and intermediates were characterized with ¹H NMR, matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry, Fourier transform infrared, and size exclusion chromatography in detail. In all cases, the molecular weight distribution of the copolymer brushes was rather narrow (weight‐average molecular weight/number‐average molecular weight < 1.2), and the linear dependence of ln[M₀]/[M] (where [M₀] is the initial monomer concentration and [M] is the monomer concentration at a certain time) on time demonstrated that the styrene polymerization was well controlled. This method has universal significance for the preparation of copolymer brushes with hydrophilic poly(ethylene oxide) as the main chain. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4361–4371, 2006     

Synthesis and characterization of pH‐sensitive and thermosensitive double hydrophilic graft copolymers

A series of poly(N‐isopropylacrylamide)‐co‐poly(N^ε‐benzyloxycarbonyl‐L ‐lysine) graft copolymers (PNIPAm‐co‐PZLLys) with different side chains (degree of polymerization, DP = 5～40) and unit ratios (from 30 to 70 mol %) were prepared via free radical polymerization, followed by cleaving benzyloxycarbonyl groups (Z groups) to obtain the double hydrophilic graft copolymer, poly(N‐isopropylacrylamide)‐co‐poly(L ‐lysine) (PNIPAm‐co‐PLLys). The pH‐ and temperature‐response properties of the graft copolymers in aqueous solution were studied. The experimental results indicate L15‐N30 and L15N‐70, that is, the PNIPAm‐co‐PLLys having the poly(L ‐lysine) of DP = 15 as side chains as well as 30 and 70 mol %, respectively, of PNIPAm as backbone, have coil‐to‐helix transitions from pH 6 to pH 12 at room temperature and form uniform nanoscale micelle‐like dispersions in aqueous solution at pH 12. The graft copolymers also could form uniform and nanoscale micelle‐like structures at 50 °C in pH 6 buffer solution due to slightly polymer aggregation. With temperature and pH increased, both the deprotonated PLLys side chains and PNIPAm backbone become hydrophobic, leading to polymer precipitation. These results illustrate that a double tunable hydrophilic graft copolymer had been successfully synthesized via a simple radical polymerization, and could form micelles without serious polymer aggregation at a lower pH and a higher temperature. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Amphiphilic polymer conetworks prepared by controlled radical polymerization using a nitroxide cross‐linker

Tandem atom transfer radical polymerization (ATRP) and nitroxide‐mediated radical polymerization (NMRP) were used to synthesize a polystyrene‐co‐poly(acrylic acid) (poly(St‐co‐AA)) network, in which the two components were interconnected by covalent bond. First, a specific cross‐linker, 1,4‐bis(1′‐(4″‐acryloyloxy‐2″,2″,6″,6″‐tetramethylpiperidinyloxy)ethyl)benzene (di‐AET), a bifunctional alkoxyamine possessing two acrylate groups, was copolymerized with tert‐butyl acrylate through ATRP to prepare a precursor gel. The gel was then used to initiate the NMRP of styrene to prepare poly(St‐co‐(t‐BA)) conetwork, in which the cross‐linkages are composed of polystyrene segments. Finally, the poly(St‐co‐(t‐BA)) conetwork was hydrolyzed to produce amphiphilic poly(St‐co‐AA) conetwork. The resulting gels show swelling ability in both organic solvent and water, which is characteristic of amphiphilic conetworks. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4141–4149, 2010     

Novel thermo‐responsive self‐assembly micelles from a double brush‐shaped PNIPAM‐g‐(PA‐b‐PEG‐b‐PA)‐g‐PNIPAM block copolymer with PNIPAM polymers as side chains

A novel double brush‐shaped copolymer with amphiphilic polyacrylate‐b‐poly(ethylene glycol)‐b‐poly acrylate copolymer (PA‐b‐PEG‐b‐PA) as a backbone and thermosensitive poly(N‐isopropylacrylamide) (PNIPAM) long side chains at both ends of the PEG was synthesized via an atom transfer radical polymerization (ATRP) route, and the structure was confirmed by FTIR, ¹H NMR, and SEC. The thermosensitive self‐assembly behavior was examined via UV‐vis, TEM, DLS, and surface tension measurements, etc. The self‐assembled micelles, with low critical solution temperatures (LCST) of 34–38 ^°C, form irregular fusiform and/or spherical morphologies with single, double, and petaling cores in aqueous solution at room temperature, while above the LCST the micelles took on more regular and smooth spherical shapes with diameter ranges from 45 to 100 nm. The micelle exhibits high stabilities even in simulated physiological media, with low critical micellization concentration (CMC) up to 5.50, 4.89, and 5.05 mg L^?1 in aqueous solution, pH 1.4 and 7.4 PBS solutions, respectively. The TEM and DLS determination reveled that the copolymer micelle had broad size distribution below its LCST while it produces narrow and homogeneous size above the LCST. The cytotoxicity was investigated by MTT assays to elucidate the application potential of the as‐prepared block polymer brushes as drug controlled release vehicles. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

The preparation of amphiphilic core‐shell nanospheres by using water‐soluble macrophotoinitiator

The amphiphilic poly(AM‐co‐SA)‐ITXH macrophotoinitiator was synthesized by precipitation photopolymerization under UV irradiation with isopropylthioxanthone (ITX) as free radical photoinitiator. A novel method has been developed to prepare amphiphilic core‐shell polymer nanospheres via photopolymerization of methyl methacrylate (MMA) in aqueous media, with amphiphilic copolymer macrophotoinitiator poly(AM‐co‐SA)‐ITXH. During polymerization, the amphiphilic macroradicals underwent in situ self‐assembly to form polymeric micelles, which promoted the emulsion polymerization of the monomer. Thus, amphiphilic core‐shell nanospheres ranging from 70 to 140 nm in diameter were produced in the absence of surfactant. The conversion of the monomer, number average molecular weights (M_n), and particle size were found to be highly dependent on the macrophotoinitiator and monomer concentration. The macrophotoinitiator and amphiphilic particles were characterized by FTIR, UV‐vis, ¹H NMR, TEM, DSC, and contact angle measurements. The results showed the particles had well‐defined amphiphilic core‐shell structure. This new method is scientifically and technologically significant because it provides a commercially viable route to a wide variety of novel amphiphilic core‐shell nanospheres. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 936–942, 2010     

Synthesis and characterization of biodegradable pH and reduction dual‐sensitive polymeric micelles for doxorubicin delivery

Novel pH and reduction dual‐sensitive biodegradable polymeric micelles for efficient intracellular delivery of anticancer drugs were prepared based on a block copolymer of methyloxy‐poly(ethylene glycol)‐b‐poly[(benzyl‐l ‐aspartate)‐co‐(N‐(3‐aminopropyl) imidazole‐l ‐aspartamide)] [mPEG‐SS‐P(BLA‐co‐APILA), MPBA] synthesized by a combination of ring‐opening polymerization and side‐chain reaction. The pH/reduction‐responsive behavior of MPBA was observed by both dynamic light scattering and UV–vis experiments. The polymeric micelles and DOX‐loaded micelles could be prepared simply by adjusting the pH of the polymer solution without the use of any organic solvents. The drug release study indicated that the DOX‐loaded micelles showed retarded drug release in phosphate‐buffered saline at pH 7.4 and a rapid release after exposure to weakly acidic or reductive environment. The empty micelles were nontoxic and the DOX‐loaded micelles displayed obvious anticancer activity similar to free DOX against HeLa cells. Confocal microscopy observation demonstrated that the DOX‐loaded MPBA micelles can be quickly internalized into the cells, and effectively deliver the drugs into nuclei. Thus, the pH and reduction dual‐responsive MPBA polymeric micelles are an attractive platform to achieve the fast intracellular release of anticancer drugs. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1771–1780     

Synthesis and characterization of grafted/crosslinked proton conducting membranes based on amphiphilic PVDF copolymer

A novel graft copolymer consisting of a poly(vinylidene fluoride‐co‐chlorotrifluoroethylene) backbone and poly(glycidyl methacrylate) side chains, that is, P(VDF‐co‐CTFE)‐g‐PGMA, was synthesized through atom transfer radical polymerization (ATRP) using CTFE units as a macroinitiator. Successful synthesis and microphase‐separated structure of the polymer were confirmed by ¹H NMR, FTIR spectroscopy, and TEM. As‐synthesized P(VDF‐co‐CTFE)‐g‐PGMA copolymer was sulfonated by sodium bisulfite, followed by thermal crosslinking with sulfosuccinic acid (SA) via the esterification to produce grafted/crosslinked polymer electrolyte membranes. The IEC values continuously increased with increasing SA content but water uptake increased with SA content up to 10 wt %, above which it decreased again as a result of competitive effect between crosslinking and hydrophilicity of membranes. At 20 wt % of SA content, the proton conductivity reached 0.057 and 0.11 S/cm at 20 and 80 °C, respectively. The grafted/crosslinked P(VDF‐co‐CTFE)‐g‐PGMA/SA membranes exhibited good mechanical properties (>400 MPa of Young's modulus) and high thermal stability (up to 300 °C), as determined by a universal testing machine (UTM) and TGA, respectively. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1110–1117, 2010     

Polyurea microcapsules from isocyanatoethyl methacrylate copolymers

The synthesis of two types of isocyanate side chain containing copolymers, poly(methyl methacrylate‐co‐isocyanatoethyl methacrylate) (P(MMA‐co‐IEM)) and poly(benzyl methacrylate‐co‐isocyanatoethyl methacrylate) (P(BnMA‐co‐IEM)), which were synthesized by Cu(0)‐mediated radical polymerization, is reported. Polymerization proceeded to high conversion giving polymers of relatively narrow molar mass distributions. The incorporation of the bulky aromatic groups in the latter copolymer rendered it sufficiently stable toward hydrolysis and enabled the isolation of the product and its characterization by ¹H and ¹³C NMR, and FTIR spectroscopy and SEC. Both P(MMA‐co‐IEM) and P(BnMA‐co‐IEM) were functionalized with dibutylamine, octylamine, and (R)‐(+)‐α‐methylbenzyl‐amine, which further proved the successful incorporation of the isocyanate groups. Furthermore, P(BnMA‐co‐IEM) was used for the fabrication of liquid core microcapsules via oil‐in‐water interfacial polymerization with diethylenetriamine as crosslinker. The particles obtained were in the size range of 10–90 µm in diameter independent of the composition of copolymer. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2698–2705     

A successive route to amphiphilic graft copolymers with a hydrophilic poly(3‐hydroxypropyl methacrylate) backbone and hydrophobic polystyrene side chains

A successive method for preparing novel amphiphilic graft copolymers with a hydrophilic backbone and hydrophobic side chains was developed. An anionic copolymerization of two bifunctional monomers, namely, allyl methacrylate (AMA) and a small amount of glycidyl methacrylate (GMA), was carried out in tetrahydrofuran (THF) with 1,1‐diphenylhexyllithium (DPHL) as the initiator in the presence of LiCl ([LiCl]/[DPHL]₀ = 2), at −50 °C. The copolymer poly(AMA‐co‐GMA) thus obtained possessed a controlled molecular weight and a narrow molecular weight distribution (M_w /M_n = 1.08–1.17). Without termination and polymer separation, a coupling reaction between the epoxy groups of this copolymer and anionic living polystyrene [poly(St)] at −40 °C generated a graft copolymer with a poly(AMA‐co‐GMA) backbone and poly(St) side chains. This graft copolymer was free of its precursors, and its molecular weight as well as its composition could be well controlled. To the completed coupling reaction solution, a THF solution of 9‐borabicyclo[3.3.1]nonane was added, and this was followed by the addition of sodium hydroxide and hydrogen peroxide. This hydroboration changed the AMA units of the backbone to 3‐hydroxypropyl methacrylate, and an amphiphilic graft copolymer with a hydrophilic poly(3‐hydroxypropyl methacrylate) backbone and hydrophobic poly(St) side chains was obtained. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1195–1202, 2000     

Synthesis of poly(vinyl acetate)‐graft‐polystyrene by a combination of cobalt‐mediated radical polymerization and atom transfer radical polymerization

Vinyl acetate and vinyl chloroacetate were copolymerized in the presence of a bis(trifluoro‐2,4‐pentanedionato)cobalt(II) complex and 2,2′‐azobis(4‐methoxy‐2,4‐dimethylvaleronitrile) at 30 °C, forming a cobalt‐capped poly(vinyl acetate‐co‐vinyl chloroacetate). The addition of 2,2,6,6‐tetramethyl‐1‐piperidinyloxy after a certain degree of copolymerization was reached afforded 2,2,6,6‐tetramethyl‐1‐piperidinyloxy‐terminated poly(vinyl acetate‐co‐vinyl chloroacetate) (PVOAc–MI; number‐average molecular weight = 31,000, weight‐average molecular weight/number‐average molecular weight = 1.24). A ¹H NMR study of the resulting PVOAc–MI revealed quantitative terminal 2,2,6,6‐tetramethyl‐1‐piperidinyloxy functionality and the presence of 5.5 mol % vinyl chloroacetate in the copolymer. The atom transfer radical polymerization (ATRP) of styrene (St) was studied with ethyl chloroacetate as a model initiator and five different Cu‐based catalysts. Catalysts with bis(2‐pyridylmethyl)octadecylamine (BPMODA) or tris(2‐pyridylmethyl)amine (TPMA) ligands provided the highest initiation efficiency and best control over the polymerization of St. The grafting‐from ATRP of St from PVOAc–MI catalyzed by copper complexes with BPMODA or TPMA ligands provided poly(vinyl acetate)‐graft‐polystyrene copolymers with relatively high polydispersity (>1.5) because of intermolecular coupling between growing polystyrene (PSt) grafts. After the hydrolysis of the graft copolymers, the cleaved PSt side chains had a monomodal molecular weight distribution with some tailing toward the lower number‐average molecular weight region because of termination. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 447–459, 2007     

Design and proof of reversible micelle‐to‐vesicle multistimuli‐responsive morphological regulations

Multistimuli‐responsive precise morphological control over self‐assembled polymers is of great importance for applications in nanoscience as drug delivery system. A novel pH, photoresponsive, and cyclodextrin‐responsive block copolymer were developed to investigate the reversible morphological transition from micelles to vesicles. The azobenzene‐containing block copolymer poly(ethylene oxide)‐b‐poly(2‐(diethylamino)ethyl methacrylate‐co‐6‐(4‐phenylazo phenoxy)hexyl methacrylate) [PEO‐b‐P(DEAEMA‐co‐PPHMA)] was synthesized by atom transfer radical polymerization. This system can self‐assemble into vesicles in aqueous solution at pH 8. On adjusting the solution pH to 3, there was a transition from vesicles to micelles. The same behavior, that is, transition from vesicles to micelles was also realizable on addition of β‐cyclodextrin (β‐CD) to the PEO‐b‐P(DEAEMA‐co‐PPHMA) solution at pH 8. Furthermore, after β‐CD was added, alternating irradiation of the solution with UV and visible light can also induce the reversible micelle‐to‐vesicle transition because of the photoinduced trans‐to‐cis isomerization of azobenzene units. The multistimuli‐responsive precise morphological changes were studied by laser light scattering, transmission electron microscopy, and UV–vis spectra. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Grafting of polyamide 6 by the anionic polymerization of ε‐caprolactam from an isocyanate bearing polystyrene backbone

The grafting of polyamide 6 (PA6) onto polystyrene (PS) can rely on the use of a copolymer of styrene (St) and 3‐isopropenyl‐α, α‐dimethylbenzene isocyanate (TMI), PS‐co‐TMI, to activate the polymerization of ε‐caprolactam (CL) in the presence of sodium ε‐caprolactam (NaCL) as an anionic catalyst. This article is aimed at answering the following key questions. First, do all the isocyanate moieties of the PS‐co‐TMI participate in the activation of the polymerization of CL? Second, what are the composition of the resulting polymer product and the structure of the resulting graft copolymer? The results show that the isocyanate moieties had all participated in the activation of the polymerization, implying that each isocyanate moiety has led to the formation of a PA6 graft. The as‐polymerized product was composed of a pure PS‐g‐PA6 graft copolymer, homo‐PA6, and unreacted CL. Moreover, when the composition of a PS‐co‐TMI/CL/NaCL system was fixed, the mass ratio between the PA6 grafts and PS backbone of the pure PS‐g‐PA6 graft copolymer was almost a constant and was almost independent of its molar mass. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4766–4776, 2008