ATRP of methyl methacrylate initiated with a bifunctional initiator bearing bromomethyl functional groups: Synthesis of the block and graft copolymers

This article reports the synthesis of the block and graft copolymers using peroxygen‐containing poly(methyl methacrylate) (poly‐MMA) as a macroinitiator that was prepared from the atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) in the presence of bis(4,4′‐bromomethyl benzoyl peroxide) (BBP). The effects of reaction temperatures on the ATRP system were studied in detail. Kinetic studies were carried out to investigate controlled ATRP for BBP/CuBr/bpy initiating system with MMA at 40 °C and free radical polymerization of styrene (S) at 80 °C. The plots of ln ([M_o]/[M_t]) versus reaction time are linear, corresponding to first‐order kinetics. Poly‐MMA initiators were used in the bulk polymerization of S to obtain poly (MMA‐b‐S) block copolymers. Poly‐MMA initiators containing undecomposed peroygen groups were used for the graft copolymerization of polybutadiene (PBd) and natural rubber (RSS‐3) to obtain crosslinked poly (MMA‐g‐PBd) and poly(MMA‐g‐RSS‐3) graft copolymers. Swelling ratio values (q_v) of the graft copolymers in CHCl₃ were calculated. The characterizations of the polymers were achieved by Fourier‐transform infrared spectroscopy (FTIR), ¹H‐nuclear magnetic resonance (¹H NMR), gel‐permeation chromatography (GPC), differential scanning calorimetry (DSC), thermogravimetric analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), and the fractional precipitation (γ) techniques. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1364–1373, 2010     

Block and random copolymerization of ε‐caprolactone,L‐, and rac‐lactide using titanium complex derived from aminodiol ligand

A series of di‐ and triblock copolymers [poly(L ‐lactide‐b‐ε‐caprolactone), poly(D,L ‐lactide‐b‐ε‐caprolactone), poly(ε‐caprolactone‐b‐L ‐lactide), and poly(ε‐caprolactone‐b‐L ‐lactide‐b‐ε‐caprolactone)] have been synthesized successfully by sequential ring‐opening polymerization of ε‐caprolactone (ε‐CL) and lactide (LA) either by initiating PCL block growth with living PLA chain end or vice versa using titanium complexes supported by aminodiol ligands as initiators. Poly(trimethylene carbonate‐b‐ε‐caprolactone) was also prepared. A series of random copolymers with different comonomer composition were also synthesized in solution and bulk of ε‐CL and D,L ‐lactide. The chemical composition and microstructure of the copolymers suggest a random distribution with short average sequence length of both the LA and ε‐CL. Transesterification reactions played a key role in the redistribution of monomer sequence and the chain microstructures. Differential scanning calorimetry analysis of the copolymer also evidenced the random structure of the copolymer with a unique T_g. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Preparation and self‐assembly of stimuli‐responsive azobenzene‐containing diblock copolymers through microwave‐assisted RAFT polymerization

This article reports on studies regarding the photoisomerization kinetics and self‐assembly behaviors of two photoresponsive diblock copolymers, poly(4‐acetoxystyrene)‐block‐poly[6‐(4‐methoxy‐azobenzene‐4′‐oxy) hexyl acrylate] (poly(StO₅₄‐b‐Cazo₉) and poly(StO₅₄‐b‐Cazo₅)), which dissolved in a THF/H₂O solution through two‐step reverse addition‐fragmentation transfer polymerization. We examined the effect of heating methods (i.e., conventional and microwave heating) on the polymerization kinetics of a 4‐acetoxystyrene‐based macrochain transfer agent (StO macro‐CTA). The kinetics studies on the homopolymerization of StO by using microwave heating demonstrated controllable characteristics with relatively narrow polydispersities at ～1.14. The diblock copolymers exhibited moderate thermal stability, with thermal decomposition temperatures greater than 343.3 °C, suggesting that the enhancement of the thermal stability was due to the incorporation of azobenzene segments into block copolymers. Poly(StO₅₄‐b‐Cazo₉) showed lower photoisomerization rate constants (k_t = 0.039 s^?1) compared with Cazo monomer (k_t = 0.097 s^?1). Micellar aggregates with a mean diameter of approximately 238.3 nm were formed by gradually adding water to the THF solution (water content = 10 vol %), and are shown in SEM and TEM images of the diblock copolymer. The results of this study contribute to the literature regarding the development of photoresponsive polymer materials. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3107–3117     

Norbornene‐functionalized PEO‐b‐PCL: A versatile platform for mikto‐arm star,umbrella‐like,and comb‐like graft copolymers

Well‐defined in‐chain norbornene‐functionalized poly(ethylene oxide)‐b‐poly(?‐caprolactone) copolymers (NB‐PEO‐b‐PCL) were synthesized from a dual clickable containing both hydroxyl‐ and alkyne‐reactive groups, namely heterofunctional norbornene 3‐exo‐(2‐exo‐(hydroxymethyl)norborn‐5‐enyl)methyl hexynoate. A range of NB‐PEO‐b‐PCL copolymers were obtained using a combination of orthogonal organocatalyzed ring‐opening polymerization (ROP) and click copper‐catalyzed azide–alkyne cycloaddition (CuAAC). Ring‐opening metathesis polymerization (ROMP) of NB‐PEO‐b‐PCL macromonomers using ruthenium‐based Grubbs’ catalysts provides comb‐like and umbrella‐like graft copolymers bearing both PEO and PCL grafts on each monomer unit. Mikto‐arm star A₂B₂ copolymers were obtained through a new strategy based on thiol–norbornene photoinitiated click chemistry between 1,3‐propanedithiol and NB‐PEO‐b‐PCL. The results demonstrate that in‐chain NB‐PEO‐b‐PCL copolymers can be used as a platform to prepare mikto‐arm star, umbrella‐, and comb‐like graft copolymers. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 4051–4061     

Synthesis of poly(β‐pinene)‐g‐poly(meth)acrylate by the combination of living cationic polymerization and atom transfer radical polymerization

New graft copolymers of β‐pinene with methyl methacrylate (MMA) or butyl acrylate (BA) were synthesized by the combination of living cationic polymerization and atom transfer radical polymerization (ATRP). β‐Pinene polymers with predetermined molecular weights and narrow molecular weight distributions (MWDs) were prepared by living cationic polymerization with the 1‐phenylethyl chloride/TiCl₄/Ti(OiPr)₄/nBu₄NCl initiating system, and the resultant polymers were brominated quantitatively by N‐bromosuccinamide in the presence of azobisisobutyronitrile, yielding poly(β‐pinene) macroinitiators with different bromine contents (Br/β‐pinene unit molar ratio = 1.0 and 0.5 for macroinitiators a and b , respectively). The macroinitiators, in conjunction with CuBr and 2,2′‐bipyridine, were used to initiate ATRP of BA or MMA. With macroinitiator a or b , the bulk polymerization of BA induced a linear first‐order kinetic plot and gave graft copolymers with controlled molecular weights and MWDs; this indicated the living nature of these polymerizations. The bulk polymerization of MMA initiated with macroinitiator a was completed instantaneously and induced insoluble gel products. However, the controlled polymerization of MMA was achieved with macroinitiator b in toluene and resulted in the desired graft copolymers with controlled molecular weights and MWDs. The structures of the obtained graft copolymers of β‐pinene with (methyl)methacrylate were confirmed by ¹H NMR spectra. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1237–1242, 2003     

Amphiphilic Block‐Graft Copolymers Poly(ethylene glycol)‐b‐(polycarbonates‐g‐palmitate) Prepared via the Combination of Ring‐Opening Polymerization and Click Chemistry

Amphiphilic block‐graft copolymers mPEG‐b‐P(DTC‐ADTC‐g‐Pal) were synthesized by ring‐opening polymerization of 2,2‐dimethyltrimethylene carbonate (DTC) and 2,2‐bis(azidomethyl)trimethylene carbonate (ADTC) with poly(ethylene glycol) monomethyl ether (mPEG) as an initiator, followed by the click reaction of propargyl palmitate and the pendant azido groups on the polymer chains. Stable micelle solutions of the amphiphilic block‐graft copolymers could be prepared by adding water to a THF solution of the polymer followed by the removal of the organic solvent by dialysis. Dynamic light scattering measurements showed that the micelles had a narrow size distribution. Transmission electron microscopy images displayed that the micelles were in spherical shape. The grafted structure could enhance the interaction of polymer chains with drug molecules and improve the drug‐loading capacity and entrapment efficiency. Further, the amphiphilic block‐graft copolymers mPEG‐b‐P(DTC‐ADTC‐g‐Pal) were low cytotoxic and had more sustained drug release behavior. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis and characterization of well‐defined [polystyrene‐b‐poly(2‐vinylpyridine)]n star‐block copolymers with poly(2‐vinylpyridine) corona blocks

This article describes the synthesis and characterization of [polystyrene‐b‐poly(2‐vinylpyridine)]_n star‐block copolymers with the poly(2‐vinylpyridine) blocks at the periphery. A two‐step living anionic polymerization method was used. Firstly, oligo(styryl)lithium grafted poly(divinylbenzene) cores were used as multifunctional initiators to initiate living anionic polymerization of styrene in benzene at room temperature. Secondly, vinylpyridine was polymerized at the periphery of these living (polystyrene)_n stars in tetrahydrofuran at ?78 °C. The resulting copolymers were characterized using size exclusion chromatography, multiangle laser light scattering, ¹H NMR, elemental analysis, and intrinsic viscosity measurements. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3949–3955, 2007     

Synthesis and characterization of block copolymers from 2‐vinylnaphthalene by anionic polymerization

The anionic polymerization of 2‐vinylnaphthalene (2VN) has been studied in tetrahydrofuran (THF) at ?78 °C and in toluene at 40 °C. 2VN polymerization in THF, toluene, or toluene/THF (99:1 v/v) initiated by sec‐butyllithium (sBuLi) indicates living characteristics, affording polymers with predefined molecular weights and narrow molecular weight distributions. Block copolymers of 2VN with methyl methacrylate (MMA) and tert‐butyl acrylate (tBA) have been synthesized successfully by sequential monomer addition in THF at ?78 °C initiated by an adduct of sBuLi–LiCl. The crossover propagation from poly(2‐vinylnaphthyllithium) (P2VN) macroanions to MMA and tBA appears to be living, the molecular weight and composition can be predicted, and the molecular weight distribution of the resulting block copolymer is narrow (weight‐average molecular/number‐average molecular weight < 1.3). Block copolymers with different chain lengths for the P2VN segment can easily be prepared by variations in the monomer ratios. The block copolymerization of 2VN with hexamethylcyclotrisiloxane also results in a block copolymer of P2VN and poly(dimethylsiloxane) (PDMS) contaminated with a significant amount of homo‐PDMS. Poly(2VN‐b‐nBA) (where nBA is n‐butyl acrylate) has also been prepared by the transesterification reaction of the poly(2VN‐b‐tBA) block copolymer. Size exclusion chromatography, Fourier transform infrared, and ¹H NMR measurements indicate that the resulting polymers have the required architecture. The corresponding amphiphilic block copolymer of poly(2VN‐b‐AA) (where AA is acrylic acid) has been synthesized by acidic hydrolysis of the ester group of tert‐butyl from the poly(2VN‐b‐tBA) copolymer. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4387–4397, 2002     

Synthesis of amphiphilic poly(methyl methacrylate‐ b‐ethylene oxide) copolymers from monohydroxy telechelic poly(methyl methacrylate) as macroinitiator

The synthesis of well‐defined poly(methyl methacrylate)‐block‐poly(ethylene oxide) (PMMA‐b‐PEO) dibock copolymer through anionic polymerization using monohydroxy telechelic PMMA as macroinitiator is described. Living anionic polymerization of methyl methacrylate was performed using initiators derived from the adduct of diphenylethylene and a suitable alkyllithium, either of which contains a hydroxyl group protected with tert‐butyldimethylsilyl moiety in tetrahydrofuran (THF) at ?78 °C in the presence of LiClO₄. The synthesized telechelic PMMAs had good control of molecular weight with narrow molecular weight distribution (MWD). The ¹H NMR and MALDI‐TOF MS analysis confirmed quantitative functionalization of chain‐ends. Block copolymerization of ethylene oxide was carried out using the terminal hydroxyl group of PMMA as initiator in the presence of potassium counter ion in THF at 35 °C. The PMMA‐b‐PEO diblock copolymers had moderate control of molecular weight with narrow MWD. The ¹H NMR results confirm the absence of trans‐esterification reaction of propagating PEO anions onto the ester pendants of PMMA. The micellation behavior of PMMA‐b‐PEO diblock copolymer was examined in water using ¹H NMR and dynamic light scattering. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2132–2144, 2008     

Synthesis of amphiphilic block–graft copolymers [poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene)‐g‐poly(acrylic acid)] and their aggregation in water

Novel block–graft copolymers [poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene)‐g‐poly(tert‐butyl acrylate)] were synthesized by the atom transfer radical polymerization (ATRP) of tert‐butyl acrylate (tBA) with chloromethylated poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene) (SEBS) as a macromolecular initiator. The copolymers were composed of triblock SEBS as the backbone and tBA as grafts attached to the polystyrene end blocks. The macromolecular initiator (chloromethylated SEBS) was prepared by successive hydrogenation and chloromethylation of SEBS. The degree of chloromethylation, ranging from 1.6 to 36.5 mol % according to the styrene units in SEBS, was attained with adjustments in the amount of SnCl₄ and the reaction time with a slight effect on the monodispersity of the starting material (SEBS). The ATRP mechanism of the copolymerization was supported by the kinetic data and the linear increase in the molecular weights of the products with conversion. The graft density was controlled with changes in the functionality of the chloromethylated SEBS. The average length of the graft chain, ranging from a few repeat units to about two hundred, was adjusted with changes in the reaction time and alterations in the initiator/catalyst/ligand molar ratio. Incomplete initiation was detected at a low conversion; moreover, for initiators with low functionality, sluggish initiation was overcome with suitable reaction conditions. The block–graft copolymers were hydrolyzed into amphiphilic ones containing poly(acrylic acid) grafts. The aggregation behavior of the amphiphilic copolymers was studied with dynamic light scattering and transmission electron microscopy, and the aggregates showed a variety of morphologies. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1253–1266, 2002     

Titanium‐mediated [CpTiCl2(OEt)] ring‐opening polymerization of lactides: A novel route to well‐defined polylactide‐based complex macromolecular architectures

Among three cyclopentadienyl titanium complexes studied, CpTiCl₂(OEt), containing a 5% excess CpTiCl₃, has proven to be a very efficient catalyst for the ring‐opening polymerization (ROP) of L ‐lactide (LLA) in toluene at 130 °C. Kinetic studies revealed that the polymerization yield (up to 100%) and the molecular weight increase linearly with time, leading to well‐defined PLLA with narrow molecular weight distributions (M_w/M_n ≤ 1.1). Based on the above results, PS‐b‐PLLA, PI‐b‐PLLA, PEO‐b‐PLLA block copolymers, and a PS‐b‐PI‐b‐PLLA triblock terpolymer were synthesized. The synthetic strategy involved: (a) the preparation of OH‐end‐functionalized homopolymers or diblock copolymers by anionic polymerization, (b) the reaction of the OH‐functionalized polymers with CpTiCl₃ to give the corresponding Ti‐macrocatalyst, and (c) the ROP of LLA to afford the final block copolymers. PMMA‐g‐PLLA [PMMA: poly(methyl methacrylate)] was also synthesized by: (a) the reaction of CpTiCl₃ with 2‐hydroxy ethyl methacrylate, HEMA, to give the Ti‐HEMA‐catalyst, (b) the ROP of LLA to afford a PLLA methacrylic‐macromonomer, and (c) the copolymerization (conventional and ATRP) of the macromonomer with MMA to afford the final graft copolymer. Intermediate and final products were characterized by NMR spectroscopy and size exclusion chromatography, equipped with refractive index and two‐angle laser light scattering detectors. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1092–1103, 2010     

Double hydrophilic block copolymers of sodium(2‐sulfamate‐3‐carboxylate)isoprene and ethylene oxide

Poly(sodium(2‐sulfamate‐3‐carboxylate)isoprene)‐b‐poly(ethylene oxide) and poly(ethylene oxide)‐b‐poly(sodium(2‐sulfamate‐1‐carboxylate)isoprene)‐b‐poly(ethylene oxide) double hydrophilic block copolymers were prepared by selective post polymerization reaction of the polyisoprene block, of poly(isoprene‐b‐ethylene oxide) diblocks or poly(ethylene oxide‐b‐isoprene‐b‐ethylene oxide) triblock precursors, with N‐chlorosulfonyl isocyanate. The precursors were synthesized by anionic polymerization high vacuum techniques and had narrow molecular weight distributions and predictable molecular weights and compositions. The resulting double hydrophilic block copolymers were characterized by FTIR and potentiometric titrations in terms of the incorporated functional groups. Their properties in aqueous solutions were studied by viscometry and dynamic light scattering. The latter techniques revealed a complex dilute solution behavior of the novel block copolymers, resulting from the polyelectrolyte character of the functionalized PI block and showing a dependence on solution ionic strength and pH. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 606–613, 2006     

Synthesis of graft copolymer by ATRP of MMA from poly(phenylacetylene)

The present report describes the synthesis of a densely grafted copolymer consisting of a rigid main chain and flexible side chains by the atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) from an ATRP initiator‐bearing poly(phenylacetylene) [poly(BrPA)]. Poly(BrPA) was obtained by the polymerization of 4‐ethynylbenzyl‐2‐bromoisobutyrate using [Rh(NBD)Cl]₂ in the presence of Et₃N. The ¹H NMR spectrum showed that poly(BrPA) was in the cis‐transoid form. Upon heating at 30 °C for 24 h the cis‐transoid form was maintained. ATRP of MMA from the poly(BrPA) was carried out at 30 °C using CuX (X = Br, Cl) as the catalyst and N,N,N′,N′,N′‐pentamethyldiethylenetriamine as the ligand, and the resulting graft copolymers were investigated with ¹H NMR and SEC. To analyze the graft structure in more detail, the graft copolymers were hydrolyzed with KOH and the resultant poly(MMA) part was investigated with ¹H NMR and SEC. The polydispersity indexes of 1.25–1.45 indicated that the graft copolymers have well‐controlled side chains. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6697–6707, 2006     

Preparation of comb‐like copolymers with amphiphilic poly(ethylene oxide)‐b‐polystyrene graft chains by combination of “graft from” and “graft onto” strategies

A novel method for preparation the comb‐like copolymers with amphihilic poly(ethylene oxide)‐block‐poly(styrene) (PEO‐b‐PS) graft chains by “graft from” and “graft onto” strategies were reported. The ring‐opening copolymerization of ethylene oxide (EO) and ethoxyethyl glycidyl ether (EEGE) was carried out first using α‐methoxyl‐ω‐hydroxyl‐poly(ethylene oxide) (mPEO) and diphenylmethyl potassium (DPMK) as coinitiation system, then the EEGE units on resulting linear copolymer mPEO‐b‐Poly(EO‐co‐EEGE) were hydrolyzed and the recovered hydroxyl groups were reacted with 2‐bromoisobutyryl bromide. The obtained macroinitiator mPEO‐b‐Poly(EO‐co‐BiBGE) can initiate the polymerization of styrene by ATRP via the “Graft from” strategy, and the comb‐like copolymers mPEO‐b‐[Poly(EO‐co‐Gly)‐g‐PS] were obtained. Afterwards, the TEMPO‐PEO was prepared by ring‐opening polymerization (ROP) of EO initiated by 4‐hydroxyl‐2,2,6,6‐tetramethyl piperdinyl‐oxy (HTEMPO) and DPMK, and then coupled with mPEO‐b‐[Poly(EO‐co‐Gly)‐g‐PS] by atom transfer nitroxide radical coupling reaction in the presence of cuprous bromide (CuBr)/N,N,N′,N″,N″‐pentamethyldiethylenetriamine (PMDETA) via “Graft onto” method. The comb‐like block copolymers mPEO‐b‐[Poly(EO‐co‐Gly)‐g‐(PS‐b‐PEO)] were obtained with high efficiency (≥90%). The final product and intermediates were characterized in detail. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1930–1938, 2009     

Synthesis of poly(dimethylsiloxane)‐containing diblock and triblock copolymers by the combination of anionic ring‐opening polymerization of hexamethylcyclotrisiloxane and nitroxide‐mediated radical polymerization of methyl acrylate,isoprene, and styrene

Poly(dimethylsiloxane)‐containing diblock and triblock copolymers were prepared by the combination of anionic ring‐opening polymerization (AROP) of hexamethylcyclotrisiloxane (D₃) and nitroxide‐mediated radical polymerization (NMRP) of methyl acrylate (MA), isoprene (IP), and styrene (St). The first step was the preparation of a TIPNO‐based alkoxyamine carrying a 4‐bromophenyl group. The alkoxyamine was then treated with Li powder in ether, and AROP of D₃ was carried out using the resulting lithiophenyl alkoxyamine at room temperature, giving functional poly(D₃) with M_w/M_n of 1.09–1.16. NMRPs of MA, St, and IP from the poly(D₃) at 120 °C gave poly(D₃‐b‐MA), poly(D₃‐b‐St), and poly(D₃‐b‐IP) diblock copolymers, and subsequent NMRPs of St from poly(D₃‐b‐MA) and poly(D₃‐b‐IP) at 120 °C gave poly(D₃‐b‐MA‐b‐St) and poly(D₃‐b‐IP‐b‐St) triblock copolymers. The poly(dimethylsiloxane)‐containing diblock and triblock copolymers were analyzed by ¹H NMR and size exclusion chromatography. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6153–6165, 2005     

PNIPAM‐b‐(PEA‐g‐PDMAEA) double‐hydrophilic graft copolymer: Synthesis and its application for preparation of gold nanoparticles in aqueous media

A series of well‐defined double‐hydrophilic graft copolymers, consisting of poly(N‐isopropylacrylamide)‐b‐poly(ethyl acrylate) (PNIPAM‐b‐PEA) backbone and poly(2‐(dimethylamino)ethyl acrylate) (PDMAEA) side chains, were synthesized by the combination of single‐electron‐transfer living radical polymerization (SET‐LRP) and atom‐transfer radical polymerization (ATRP). PNIPAM‐b‐PEA backbone was first prepared by sequential SET‐LRP of N‐isopropylacrylamide and 2‐hydroxyethyl acrylate at 25 °C using CuCl/tris(2‐(dimethylamino)ethyl)amine as catalytic system followed by the transformation into the macroinitiator by treating the pendant hydroxyls with 2‐chloropropionyl chloride. The final graft copolymers with narrow molecular weight distributions were synthesized by ATRP of 2‐(dimethylamino)ethyl acrylate initiated by the macroinitiator at 40 °C using CuCl/tris(2‐(dimethylamino)ethyl)amine as catalytic system via the grafting‐from strategy. These copolymers were employed to prepare stable colloidal gold nanoparticles with controlled size in aqueous solution without any external reducing agent. The morphology and size of the nanoparticles were affected by the length of PDMAEA side chains, pH value, and the feed ratio of the graft copolymer to HAuCl₄. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1811–1824, 2009     

Synthesis and characterization of model polybutadiene‐1,4‐b‐polydimethylsiloxane‐b‐polybutadiene‐1,4 copolymers

Model copolymers of poly(butadiene) (PB) and poly(dimethylsiloxane) (PDMS), PB‐b‐PDMS‐b‐PB, were synthesized by sequential anionic polymerization (high vacuum techniques) of 1,3‐butadiene and hexamethylciclotrisiloxane (D₃) on sec‐BuLi followed by chlorosilane‐coupling chemistry. The synthesized copolymers were characterized by nuclear magnetic resonance (¹H NMR), size‐exclusion chromatography (SEC), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). SEC and ¹H NMR results showed low polydispersity indexes (M_w/M_n) and variable siloxane compositions, whereas DSC and TGA experiments indicated that the thermal stability of the triblock copolymers depends on the PDMS composition. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2726–2733, 2007     

Synthesis,reactivity, and optoelectronic properties of poly(3‐alkenylthiophene) diblock copolymers

Poly(3‐hexylthiophene)‐b‐poly(3‐pentenylthiophene) and poly(3‐hexylthiophene)‐b‐poly(3‐undecenylthiophene) diblock copolymers have been synthesized by McCullough method. X‐ray diffraction analysis of the diblock copolymers displayed all the reflection peaks specific to regioregular poly(3‐hexylthiophene), indicating that the presence of poly(3‐alkenylthiophene) block does not affect the packing of the polymer in the solid state. The synthesized diblock copolymers were subjected to hydroboration/oxidation and hydrosilation to demonstrate the reactivity of the alkenyl substituents. Furthermore, poly(3‐hexylthiophene)‐b‐poly(3‐pentenylthiophene) was used as a chain transfer agent for the ruthenium‐catalyzed ring‐opening metathesis polymerization of cyclooctene to generate a polycyclooctene graft copolymer, which was hydrogenated to give poly(3‐hexylthiophene)‐b‐poly(3‐pentenylthiophene‐g‐polyethylene). The opto‐electronic properties and the morphology of the synthesized polymers have been investigated. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Syntheses of graft and star copolymers possessing polyolefin branches by using polyolefin macromonomer

Graft and star copolymers having poly(methacrylate) backbone and ethylene–propylene random copolymer (EPR) branches were successfully synthesized by radical copolymerization of an EPR macromonomer with methyl methacrylate (MMA). EPR macromonomers were prepared by sequential functionalization of vinylidene chain‐end group in EPR via hydroalumination, oxidation, and esterification reactions. Their copolymerizations with MMA were carried out with monofunctional and tetrafunctional initiators by atom transfer radical polymerization (ATRP). Gel‐permeation chromatography and NMR analyses confirmed that poly(methyl methacrylate) (PMMA)‐g‐EPR graft copolymers and four‐arm (PMMA‐g‐EPR) star copolymers could be synthesized by controlling EPR contents in a range of 8.6–38.1 wt % and EPR branch numbers in a range of 1–14 branches. Transmission electron microscopy of these copolymers demonstrated well‐dispersed morphologies between PMMA and EPR, which could be controlled by the dispersion of both segments in the range between 10 nm and less than 1 nm. Moreover, the differentiated thermal properties of these copolymers were demonstrated by differential scanning calorimetry analysis. On the other hand, the copolymerization of EPR macromonomer with MMA by conventional free radical polymerization with 2,2′‐azobis(isobutyronitrile) also gave PMMA‐g‐EPR graft copolymers. However, their morphology and thermal property remarkably differed from those of the graft copolymers obtained by ATRP. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5103–5118, 2005     

A novel fluorine‐containing graft copolymer bearing perfluorocyclobutyl aryl ether‐based backbone and poly(methyl methacrylate) side chains

A series of novel graft copolymers consisting of perfluorocyclobutyl aryl ether‐based backbone and poly(methyl methacrylate) side chains were synthesized by the combination of thermal [2π + 2π] step‐growth cycloaddition polymerization of aryl bistrifluorovinyl ether monomer and atom transfer radical polymerization (ATRP) of methyl methacrylate. A new aryl bistrifluorovinyl ether monomer, 2‐methyl‐1,4‐bistrifluorovinyloxybenzene, was first synthesized in two steps from commercially available reagents, and this monomer was homopolymerized in diphenyl ether to provide the corresponding perfluorocyclobutyl aryl ether‐based homopolymer with methoxyl end groups. The fluoropolymer was then converted to ATRP macroinitiator by the monobromination of the pendant methyls with N‐bromosuccinimide and benzoyl peroxide. The grafting‐from strategy was finally used to obtain the novel poly(2‐methyl‐1,4‐bistrifluorovinyloxybenzene)‐g‐poly(methyl methacrylate) graft copolymers with relatively narrow molecular weight distributions (M_w/M_n ≤ 1.46) via ATRP of methyl methacrylate at 50 °C in anisole initiated by the Br‐containing macroinitiator using CuBr/dHbpy as catalytic system. These fluorine‐containing graft copolymers can dissolve in most organic solvents. This is the first example of the graft copolymer possessing perfluorocyclobutyl aryl ether‐based backbone. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010