Synthesis and Functionalization of Isotactic Poly(propylene) Containing Pendant Styrene Groups

Summary: Copolymerization of propylene and 1,4‐divinylbenzene was successfully performed by a MgCl₂‐supported TiCl₄ catalyst, yielding isotactic poly(propylene) (i‐PP) polymers containing a few pendant styrene groups. With a metalation reaction with butyllithium and a hydrochlorination reaction with dry hydrogen chloride, the pendant styrene groups were quantitatively transformed into benzyllithium and 1‐chloroethylbenzene groups, respectively, which allowed the synthesis of i‐PP‐based graft copolymers by living anionic and atom transfer radical (ATRP) polymerization mechanisms.

The incorporation of styrene pendant groups into isotactic poly(propylene) using a Zeigler–Natta catalyst gave functionalized polymers able to undergo living anionic and atom transfer radical (ATRP) polymerizations.     

Synthesis of polypropylene graft copolymers by the combination of a polypropylene copolymer containing pendant vinylbenzene groups and atom transfer radical polymerization

This article discusses a facile and inexpensive reaction process for preparing polypropylene‐based graft copolymers containing an isotactic polypropylene (i‐PP) main chain and several functional polymer side chains. The chemistry involves an i‐PP polymer precursor containing several pendant vinylbenzene groups, which is prepared through the Ziegler–Natta copolymerization of propylene and 1,4‐divinylbenzene mediated by an isospecific MgCl₂‐supported TiCl₄ catalyst. The selective monoenchainment of 1,4‐divinylbenzene comonomers results in pendant vinylbenzene groups quantitatively transformed into benzyl halides by hydrochlorination. In the presence of CuCl/pentamethyldiethylenetriamine, the in situ formed, multifunctional, polymeric atom transfer radical polymerization initiators carry out graft‐from polymerization through controlled radical polymerization. Some i‐PP‐based graft copolymers, including poly(propylene‐g‐methyl methacrylate) and poly(propylene‐g‐styrene), have been prepared with controlled compositions. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 429–437, 2005     

Synthesis of polyallene‐based graft copolymer via 6‐methyl‐1,2‐heptadien‐4‐ol and styrene

A series of well‐defined graft copolymers with a polyallene‐based backbone and polystyrene side chains were synthesized by the combination of living coordination polymerization of 6‐methyl‐1,2‐heptadien‐4‐ol and atom transfer radical polymerization (ATRP) of styrene. Poly(alcohol) with polyallene repeating units were prepared via 6‐methyl‐1,2‐heptadien‐4‐ol by living coordination polymerization initiated by [(η³‐allyl)NiOCOCF₃]₂ firstly, followed by transforming the pendant hydroxyl groups into halogen‐containing ATRP initiation groups. Grafting‐from route was employed in the following step for the synthesis of the well‐defined graft copolymer: polystyrene was grafted to the backbone via ATRP of styrene. The cleaved polystyrene side chains show a narrow molecular weight distribution (M_w/M_n = 1.06). This kind of graft copolymer is the first example of graft copolymer via allene derivative and styrenic monomer. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5509–5517, 2007     

Preparation of macroreticular redox resins with hydroquinone and catechol units as pendant groups and their properties

Macroreticular redox resins with hydroquinone and catechol units as pendant groups were prepared by the Friedel-Crafts reaction of macroreticular styrene/divinylbenzene copolymer with 2,5- and 3,4-dimethoxybenzyl chlorides, followed by removal of the methyl groups with hydrobromic acid. The redox capacity of the macroreticular resins was determined by oxidation of hydrazobenzene with resins in oxidized form. Resins with 1,4-benzoquinone units were capable of oxidizing hydrazobenzene, whereas those with 1,2-benzoquinone (catechol quinone) units exhibited no apparent oxidative ability; this seems to be due to a complex formation between azobenzene and the catechol units in the reduced resins. Adsorption of metallic ions onto catechol-containing resins showed a high selectivity for Hg²⁺ ion. The effects of pH, reaction time, and ion concentration on the adsorption were also studied.     

Preparation of a copolymer of methyl methacrylate and 2‐(dimethylamino)ethyl methacrylate with pendant 4‐benzyloxy‐2,2,6,6‐tetramethyl‐1‐piperidinyloxy and its initiation of the graft polymerization of styrene by a controlled radical mechanism

The macroinitiator of a copolymer (PMD_BTM) of methyl methacrylate (MMA) and 2‐(dimethylamino)ethyl methacrylate (DAMA) with 4‐benzyloxy‐2,2,6,6‐tetramethyl‐1‐piperidinyloxy (BTEMPO) pendant groups was prepared by the photochemical reaction of tertiary amine groups of the copolymer with benzophenone in the presence of BTEMPO. The radical copolymerization of MMA and DAMA was carried out first with azo‐bis‐isobutyronitrile (AIBN) as an initiator; then, the dimethylamine groups of the copolymer constituted a charge‐transfer complex with benzophenone under UV irradiation, and the methylene of ternary amine and diphenyl methanol radicals were produced. The former was capped by BTEMPO, and the nitroxide (BTEMPO) was attached to the polymeric backbone. The amount of pendant BTEMPO on PMD_BTM was measured by ¹H NMR. PMD_BTM initiated the graft polymerization of styrene via a controlled radical mechanism, and the molecular weight of the PMD‐g‐polystyrene increased with the polymerization time. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 604–612, 2001     

Precision synthesis of graft copolymers via living cationic polymerization of p‐acetoxystyrene followed by friedel–crafts‐type termination reaction

This study describes a novel precision synthesis strategy for graft copolymers using Friedel–Crafts‐type termination reaction between a cationically prepared poly(styrene derivative) and the naphthyl side groups from a poly(vinyl ether) main chain. The pendant alkoxynaphthyl groups on the poly(vinyl ether) efficiently terminated the living cationic polymerization of p‐acetoxystyrene (AcOSt) with SnCl₄ in the presence of ethyl acetate as an added base. This research provides the first example of a well‐defined graft copolymer prepared using this method. The resulting polymer contained 40 poly‐(AcOSt) branches, as calculated from the M_w determined via gel permeation chromatography–MALS analysis, which was in good agreement with the estimated number of branches obtained from ¹H NMR analysis. The acetoxy groups in the grafted poly(AcOSt) chains were easily converted into phenolic hydroxy groups under basic conditions. The as‐obtained graft copolymer with poly(p‐hydroxystyrene) side chains exhibited a pH‐sensitive phase separation in water. The synthetic method for preparing the graft copolymers was also effective in the living cationic polymerizations of other styrene derivatives. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4675–4683     

Preparation of reactive block copolymers and their transformation to hollowed nanostructures

A novel polymeric hollow nanostructure was generated using micellar template method through a three‐step procedure. First, the block copolymers were synthesized via ring‐opening metathesis polymerization by sequentially adding monomers 7‐oxanorborn‐5‐ene‐exo‐exo‐2,3‐dicarboxylic acid dimethyl ester and the mixture of norbornene and 2,3‐bis(2‐bromoisobutyryloxymethyl)‐5‐norbornene in chloroform, and also atom transfer radical polymerization of 4‐(3‐butenyl)styrene was carried out by using the as‐obtained block copolymer poly(7‐oxanorborn‐5‐ene‐exo,exo‐2,3‐dicarboxylic acid dimethylester)‐block‐poly(norbornene‐co‐2,3‐bis(2‐bromoisobutyryloxymethyl)‐5‐norbornene as macroinitiator to afford a graft copolymer bearing poly(4‐(3‐butenyl)styrene) branch poly(7‐oxanorborn‐5‐ene‐exo,exo‐2,3‐dicarboxylic acid dimethylester)‐block‐poly(norbornene‐co‐2,3‐bis(2‐bromoisobutyryloxymethyl)‐5‐norbornene)‐graft‐poly(4‐(3‐butenyl)styrene). Second, the shell‐crosslinked micelles were prepared by ruthenium‐mediated ring‐closing metathesis of poly(4‐(3‐butenyl)styrene) branches in intramicelle formed from the copolymers self‐assembly spontaneously in toluene. Finally, the hollowed spherical nanoparticles were presented by removing the micellar copolymer backbone through the cleavage of the ester bonds away from the crosslinked network of branches. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Graft copolymers of polyethylene by atom transfer radical polymerization

Poly(ethylene‐g‐styrene) and poly(ethylene‐g‐methyl methacrylate) graft copolymers were prepared by atom transfer radical polymerization (ATRP). Commercially available poly(ethylene‐co‐glycidyl methacrylate) was converted into ATRP macroinitiators by reaction with chloroacetic acid and 2‐bromoisobutyric acid, respectively, and the pendant‐functionalized polyolefins were used to initiate the ATRP of styrene and methyl methacrylate. In both cases, incorporation of the vinyl monomer into the graft copolymer increased with extent of the reaction. The controlled growth of the side chains was proved in the case of poly(ethylene‐g‐styrene) by the linear increase of molecular weight with conversion and low polydispersity (M_w /M_n < 1.4) of the cleaved polystyrene grafts. Both macroinitiators and graft copolymers were characterized by ¹H NMR and differential scanning calorimetry. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2440–2448, 2000     

Hydrogen‐Assisted Unique Incorporation of 1,4‐Divinylbenzene in Copolymerization with Propylene Using an Isospecific Zirconocene Catalyst

Summary: Propylene was copolymerized with 1,4‐divinylbenzene (1,4‐DVB) using rac‐Me₂Si(2‐Me‐4‐Ph‐Ind)₂ZrCl₂ and MAO in the presence of hydrogen. ¹H NMR spectra of the obtained copolymer confirmed the successful incorporation of 1,4‐DVB. ¹³C NMR analysis revealed a unique copolymer structure with the incorporated 1,4‐DVB units predominantly forming 1,4‐substituted phenyl repeating units in the polymer main chain. A plausible mechanism involving spontaneous insertion of terminal styryl into Zr‐H species was proposed to rationalize the unique incorporation of 1,4‐DVB.

Copolymerization of propylene with 1,4‐divinylbenzene in the presence of hydrogen.     

Vinyl-Divinyl Copolymerization: Copolymerization and Network Formation from Styrene and p- and m-Divinylbenzene

The composition of copolymers of p- and m-divinylbenzene with styrene was determined by infrared spectrometry during copolymerization and compared with values calculated on the assumption that the polymerizing system is homogeneous, and the reactivities both of the vinyl groups in the monomers and of the pendant vinyl groups are independent of the extent of copolymerization. At lower conversions the content of all divinylbenzene units, and especially that of the pendant vinyl groups in the copolymer, is lower than calculated, whereas at higher conversions a fraction of pendant vinyl groups does not react. The conversions at the gel point do not depend on the concentration of divinylbenzene; at higher percentages of the divinyl monomer or dilution of the system they are higher for p- than for m-divinylbenzene, although p-divinylbenzene copolymers contain more divinylbenzene units at the same conversion. The deviations are explained by inhomogeneous copolymerization caused by locally different concentration of the vinyl     

Copolymerization of norbornene and styrene catalyzed by a novel anilido–imino nickel complex/methylaluminoxane system

Copolymerizations of norbornene with styrene were carried out with a catalytic system of anilido–imino nickel complex (ArN?CHC₆H₄NAr)NiBr (Ar = 2,6‐dimethylphenyl) and methylaluminoxane in toluene. The influence of the comonomer feed content and polymerization temperature on the conversion and composition of the copolymers with (ArN?CHC₆H₄NAr)NiBr/methylaluminoxane was investigated. An increase in the initial styrene feed content led to an increase in the incorporated styrene content of the resulting copolymer. The determination of the reactivity ratios showed a much high reactivity for norbornene (reactivity ratio for styrene = 0.26, reactivity ratio for norbornene = 20.78), which was consistent with a coordination mechanism. NMR analysis of the end groups further confirmed that the chain was initiated through a styrene secondary insertion or a norbornene insertion into Ni? H and terminated through β‐H elimination from an inserted styrene unit. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5237–5246, 2006     

Scale-up synthesis of vinyl polymer-grafted nano-sized silica by radical polymerization of vinyl monomers initiated by surface initiating groups in the solvent-free dry-system

For the purpose of the prevention of the environmental pollution and the simplification of reaction process, the scale-up radical graft polymerization of vinyl monomers onto nano-sized silica surface initiated by azo groups and peroxycarbonate groups previously introduced onto the surface in the solvent-free dry-system was investigated. The introduction of azo groups onto the silica surface was achieved by the reaction of surface amino groups with 4,4′-azobis(4-cyanopentanoic acid chloride). On the other hand, the introduction of peroxycarbonate groups onto the silica surface was achieved by Michael addition of surface amino groups to t-butylperoxy-2-methacryloyloxyethylcarbonate. The graft polymerization of vinyl monomers onto the surface was successfully achieved by splaying monomers to nano-sized silica having azo and peroxycarbonate groups in solvent-free dry-system. It is interesting to note that the formation of ungrafted polymer was depressed in comparison with graft polymerization in solution: the grafting efficiency was 90-95%. In addition, in the solvent-free dry-system, the grafting of copolymer having pendant peroxycarbonate groups onto the nano-sized silica surface and the radical postgraft polymerization of styrene initiated by the pendant initiating groups of the grafted copolymer chain on the silica surface was investigated.     

Grafting of poly(styrene‐co‐p‐chloromethyl styrene) with ethyl methacrylate via atom transfer radical polymerization catalyzed by CuCl/1,2‐dipiperidinoethane

Poly(styrene‐graft‐ethyl methacrylate) graft copolymer was prepared by atom transfer radical polymerization (ATRP) with poly(styrene‐co‐p‐chloromethyl styrene)s in various compositions as macroinitiator in the presence of CuCl/1,2‐dipiperidinoethane at 130 °C in N,N‐dimethylformamide. Both macroinitiators and graft copolymers were characterized by elemental analysis, IR, ¹H and ¹³C NMR, and differential scanning calorimetry. 1,2‐Dipiperidinoethane was an effective ligand of CuCl for ATRP in the graft copolymerization. The controlled growth of the side chain provided the graft copolymers with polydispersities of 1.60–2.05 in the case of poly(styrene‐co‐p‐chloromethyl styrene) (62:38) macroinitiator. Thermal stabilities of poly(styrene‐graft‐ethyl methacrylate) graft copolymers were investigated by thermogravimetric analysis as compared with those of the macroinitiators. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 668–673, 2003     

Nitroxide mediated living radical polymerization of styrene onto poly (vinyl chloride)

Nitroxide‐mediated ‘living’ free radical polymerisation (LREP) was employed for the first time to prepare graft copolymer by having arylated poly (vinyl chloride) (PVC‐Ph) as a backbone and polystyrene (PS) as branches. The graft copolymerization of styrene was initiated by arylated PVC carrying 2,2,6,6‐tetramethyl‐1‐piperidinyloxy (TEMPO) groups as a macroinitiator. Thus, the arylated PVC was prepared in the mild conditions and these reaction conditions could overcome the problem of gelation and crosslinking in polymers. Then, 1‐hydroxy TEMPO was synthesized by the reduction of TEMPO with sodium ascorbate. This functional nitroxyl compound was coupled with brominated arylated PVC (PVC‐Ph‐Br). The resulting macro‐initiator (PVC‐Ph‐TEMPO) for ‘living’ free radical polymerization was then heated in the presence of styrene to form graft copolymer. DSC, GPC, ¹HNMR, and FT‐IR spectroscopy were employed to investigate the structure of the polymers. Copyright © 2007 John Wiley & Sons, Ltd.     

Effect of the co‐catalyst on the polymerization of ethylene and styrene by nickel‐diimine complexes

The attempt to copolymerize ethylene and styrene using η³‐methallyl‐nickel‐diimine {[η³‐2‐MeC₃H₄]Ni[1,4‐bis(2,6‐diisopropylphenyl)C₂H₂N₂][PF₆]} ( 1 ) associated with MAO or TMA produces polystyrene, polyethylene and polyethylene with styrene end groups. Characteristics of the formed polymer depend on the reaction conditions. The presence of styrene in the medium reduces the polymerization productivity and the molecular weight of polyethylene. Incorporation of styrene into polyethylene is favored by a 1 /ethylene/MAO pre‐contact time and depends on the amount of styrene. Maximum incorporation was 4.4 wt.‐%. If styrene is introduced after the pre‐contact time, a bimodal product distribution is observed, suggesting the occurrence of two different catalytic species. If the co‐catalyst is changed from MAO to TMA, no copolymer is formed but the presence of styrene leads to higher amounts of branched polyethylene.     

Facile synthesis of core‐surface crosslinked nanoparticles by interblock RAFT polymerization

A new, efficient method for synthesizing stable nanoparticles with poly(ethylene oxide) (PEO) functionalities on the core surface, in which the micellization and crosslinking reactions occur in one pot, has been developed. First, amphiphilic PEO‐b‐PS copolymers were synthesized by reversible addition fragmentation chain transfer (RAFT) radical polymerization of styrene using (PEO)‐based trithiocarbonate as a macro‐RAFT agent. The low molecular weight PEO‐b‐PS copolymer was dissolved in isopropyl alcohol where the block copolymer self‐assembled as core‐shell micelles, and then the core‐shell interface crosslink was performed using divinylbenzene as a crosslinking agent and 2,2′‐azobisisobutyronitrile as an initiator. The design of the amphiphilic RAFT agent is critical for the successful preparation of core‐shell interface crosslinked micellar nanoparticles, because of RAFT functional groups interconnect PEO and polystyrene blocks. The PEO functionality of the nanoparticles surface was confirmed by ¹H NMR and FTIR. The size and morphology of the nanoparticles was confirmed by scanning electron microscopy, transmission electron microscopy, and dynamic laser light scattering analysis. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Anionic copolymerization of 2,3,4,5,6-pentafluorostyrene and divinylbenzene

Anionic copolymerizations of 2,3,4,5,6-pentafluorostyrene (PFS) with 1,3-divinylbenzene (m-DVB) and 1,4-divinylbenzene (p-DVB) were performed by using lithium diisopropylamide as an initiator in order to synthesize the fluorine-containing linear polymer with pendant vinyl groups. The products were soluble copolymers possessing both PFS and DVB monomeric units, and the DVB monomeric unit in copolymer had pendant vinyl group. This copolymerization reaction took a much longer time than that of styrene with DVB. The copolymerization parameter of this system was examined from copolymer composition curves. In this system, m-DVB was found to be more reactive than p-DVB. The reactivity of copolymerization was largely influenced by the reactivity of active species. © 1993 John Wiley & Sons, Inc.     

Copolymerization of ethylene with styrene catalyzed by a linked bis(phenolato) titanium catalyst

Copolymerization of ethylene with styrene, catalyzed by 1,4‐dithiabutanediyl‐linked bis(phenolato) titanium complex and methylaluminoxane, produced exclusively ethylene–styrene copolymers with high activity. Copolymerization parameters were calculated to be r_E = 1.2 for ethylene and r_S = 0.031 for styrene, with r_E r_S = 0.037 indicating preference for alternating copolymerization. The copolymer microstructure can be varied by changing the ratio between the monomers in the copolymerization feed, affording copolymers with styrene content up to 68%. The copolymer microstructure was fully elucidated by ¹³C NMR spectroscopy revealing, in the copolymers with styrene content higher than 50%, the presence of long styrene–styrene homosequences, occasionally interrupted by isolated ethylene units. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1908–1913, 2006     

Highly thermostable and low birefringent norbornene‐styrene copolymers with advanced optical properties: A potential plastic substrate for flexible displays

This article reports the synthesis and characterization of an extremely high thermostable cyclic olefin copolymer with advanced optical properties resulting from the vinyl addition copolymerization of norbornene with styrene catalyzed by a substituted fluorenylamidodimethyltitanium catalyst [Me₂Si(3,6‐tBu₂Flu)(tBuN)]TiMe₂ activated with a [Ph₃C] [B(C₆F₅)₄]/Al(iBu)₃ cocatalyst using o‐dichlorobenzene as solvent. The prepared copolymer possesses a glass transition temperature as high as polyimide (T_g > 300 °C) and a high transmittance which is comparable with that of the conventional optical resins ([T] > 90%). The incorporation of polystyrene, which exhibits a negative birefringence into the vinyl‐added polynorbornene that possesses an intrinsic positive birefringence, effectively reduced the birefringent magnitude of the norbornene‐styrene copolymer due to a mutual compensation between these opposite‐sign birefringences. The absence of any functional and aromatic heterocyclic groups and the presence of highly hydrophobic saturated bicyclic rings in the copolymer main chains effectively prevented the diffusion of water/oxygen and thus enhanced the dimensional and optical stabilities of the material. Preliminary results on the characterization of the thermal stability, mechanical, and optical properties of the vinyl‐added norbornene‐styrene copolymers indicate that they satisfy all the rigorous requirements for a polymer to be applied as a flexible substrate for the manufacturing of the flexible displays. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Amphiphilic PEG‐grafted poly(ester‐carbonate)s: Synthesis and diverse nanostructures in water

Novel biodegradable amphiphilic graft copolymers containing hydrophobic poly(ester‐carbonate) backbone and hydrophilic poly(ethylene glycol) (PEG) side chains were synthesized by a combination of ring‐opening polymerization and “click” chemistry. First, the ring‐opening copolymerization of 5,5‐dibromomethyl trimethylene carbonate (DBTC) and ε‐caprolactone (CL) was performed in the presence of stannous octanoate [Sn(Oct)₂] as catalyst, resulting in poly(DBTC‐co‐CL) with pendant bromo groups. Then the pendant bromo groups were completely converted into azide form, which permitted “click” reaction with alkyne‐terminated PEG by Huisgen 1,3‐dipolar cycloadditions to give amphiphilic biodegradable graft copolymers. The graft copolymers were characterized by proton nuclear magnetic resonance (¹H NMR), Fourier transform infrared spectra and gel permeation chromatography measurements, which confirmed the well‐defined graft architecture. These copolymers could self‐assemble into micelles in aqueous solution. The size and morphologies of the copolymer micelles were measured by transmission electron microscopy and dynamic light scattering, which are influenced by the length of PEG and grafting density. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.