Grafting on polybutadiene with polytetrahydrofuran macroperoxyinitiators. Postpolymerization studies

Grafting reactions of polybutadiene with macro peroxy initiators and postpolymerization were studied. The cationic polymerization of tetrahydrofuran (THF) initiated by the cationic species derived from bis-(4-bromomethylbenzoyl) peroxide (BBP) or bis-(3,5-dibromomethylbenzoyl) peroxide (BDBP) gave the PTHF macroperoxy initiator (MPI). PTHF-b-PMMA macroperoxy initiator (MPIb) was also obtained by the redox polymerization of methyl methacrylate initiated with the hydroxyl ends of PTHF and Ce(IV) salts without decomposing the peroxide groups in the middle. Macroperoxy initiators thermally grafted on cis-polybutadiene (PBD) with thermal curing to yield graft copolymers containing crosslinked and soluble parts, which were separated by the sol-gel analysis. FTIR spectra of the crosslinked samples indicated the characteristic signals of the PTHF, PBD and PMMA blocks. The crosslinked copolymers decomposed at around 470 °C. Postpolymerization of the crosslinked products indicated the increase in crosslinking density which has been followed by measuring the gradual increase of swelling values. Postpolymerization crosslinking was estimated as a first order reaction rate.     

Synthesis of polyisoprene–poly(methyl methacrylate) block copolymers via a two‐electron‐transfer mechanism

Supramolecular complexes of alkali metals were used as catalysts in the polymerization of isoprene via a two‐electron‐transfer mechanism. The obtained polyisoprene, having a living end group, was subsequently used to initiate methyl methacrylate polymerization in tetrahydrofuran. Polyisoprene–poly(methyl methacrylate) block copolymers were obtained, and their structure was established with ¹H NMR, gel permeation chromatography, differential scanning calorimetry, and experiments of selective extraction. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1086–1092, 2006     

Degradable polymer networks and star polymers based on mixtures of two cleavable dimethacrylate crosslinkers: Synthesis,characterization, and degradation

Mixtures of two cleavable dimethacrylate crosslinkers, the hydrolyzable di(methacryloyloxy‐1‐ethoxy)methane (DMOEM) and the thermolyzable 1,1‐ethylenediol dimethacrylate (EDDMA), were used for the preparation of neat crosslinker polymer networks, randomly crosslinked polymer networks of methyl methacrylate (MMA), and star polymers of MMA, using group transfer polymerization in tetrahydrofuran (THF). All star polymers and randomly crosslinked polymer networks containing mixtures of the hydrolyzable DMOEM and the thermolyzable EDDMA crosslinkers gave THF‐soluble final products when subjected to sequential thermolysis and hydrolysis, in this order. When applying sequential hydrolysis and thermolysis, only the star polymers with an EDDMA crosslinker content equal to or higher than 50% gave THF‐soluble final products. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5853–5870, 2009     

Synthesis of comb‐shaped poly(methyl methacrylate)‐b‐poly(polytetrahydrofuran acrylate) under 60Co γ‐ray irradiation

Comb‐shaped graft copolymers with poly(methyl methacrylate) as a handle were synthesized by the macromonomer technique in two steps. First, polytetrahydrofuran acrylate (A‐PTHF), prepared by the living cationic ring‐opening polymerization of tetrahydrofuran, underwent homopolymerization with 1‐(ethoxycarbonyl)prop‐1‐yl dithiobenzoate as an initiator under ⁶⁰Co γ irradiation at room temperature; Second, the handle of the comb‐shaped copolymers was prepared by the block copolymerization of methyl methacrylate with P(A‐PTHF) as a macroinitiator under ⁶⁰Co γ irradiation. The two‐step polymerizations were proved to be controlled with the following evidence: the straight line of ln[M]₀/[M] versus the polymerization time, the linear increase in the number‐average molecular weight with the conversion, and the relatively narrow molecular weight distribution. The structures of the P(A‐PTHF) and final comb‐shaped copolymers were characterized by ¹H NMR spectroscopy and gel permeation chromatography. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3367–3378, 2002     

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     

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     

Anionic polymerization and copolymerization of 1-cyanobutadiene

A stereospecific synthesis of trans-1-cyanobutadiene is described. This monomer was polymerized by n-butyl lithium in toluene and in tetrahydrofuran to yield sparingly soluble products. In both solvents, the concatenation was predominatly trans-1,4 with a little cis-1,4 and 3,4 content. Copolymers with methyl methacrylate and methyl pentadienoate were prepared in the same way: the reactivity ratios differed markedly in the two solvents being more nearly ideal in tetrahydrofuran.     

Synthesis and characterization of poly(methyl methacrylate)/casein nanoparticles with a well‐defined core‐shell structure

Well‐defined, core‐shell poly(methyl methacrylate) (PMMA)/casein nanoparticles, ranging from 80 to 130 nm in diameter, were prepared via a direct graft copolymerization of methyl methacrylate (MMA) from casein. The polymerization was induced by a small amount of alkyl hydroperoxide (ROOH) in water at 80 °C. Free radicals on the amino groups of casein and alkoxy radicals were generated concurrently, which initiated the graft copolymerization and homopolymerization of MMA, respectively. The presence of casein micelles promoted the emulsion polymerization of the monomer and provided particle stability. The conversion and grafting efficiency of the monomer strongly depended on the type of radical initiator, ROOH concentration, casein to MMA ratio, and reaction temperature. The graft copolymers and homopolymer of PMMA were isolated and characterized with Fourier transform infrared spectroscopy and differential scanning calorimetry. The molecular weight determination of both the grafted and homopolymer of PMMA suggested that the graft copolymerization and homopolymerization of MMA proceeded at a similar rate. The transmission electron microscopic image of the nanoparticles clearly showed a well‐defined core‐shell morphology, where PMMA cores were coated with casein shells. The casein shells were further confirmed with a zeta‐potential measurement. Finally, this synthetic method allowed us to prepare PMMA/casein nanoparticles with a solid content of up to 31%. Thus, our new process is commercially viable. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3346–3353, 2003     

Donor-acceptor complexes in copolymerization. L. Preparation and microstructure of chlorine-containing alternating conjugated diene–acceptor monomer copolymers

Neighboring monomer units cause significant shifts in the infrared absorption peaks attributed to cis- and trans-1,4 units in conjugated diene-acceptor monomer copolymers. Conjugated diene-maleic anhydride alternating copolymers apparently have a predominantly cis-1,4-structure, while alternating diene-SO₂ copolymers have a predominantly trans-1,4 structure. Alternating copolymers of butadiene, isoprene, and pentadiene-1,3 with α-chloroacrylonitrile and methyl α-chloroacrylate, prepared in the presence of Et_1.5AlCl_1.5(EASC), have trans-1,4 unsaturation. Alternating copolymers of chloroprene with acrylonitrile, methyl acrylate, methyl methacrylate, α-chloroacrylonitrile, and methyl α-chloroacrylate prepared in the presence of EASC-VOCl₃ have trans-1,4 configuration. The reaction between chloroprene and acrylonitrile in the presence of AlCl₃ yields the cyclic Diel-Alder adduct in the dark and the alternating copolymer under ultraviolet irradiation. The equimolar, presumably alternating, copolymers of chloroprene with methyl acrylate and methyl methacrylate undergo cyclization at 205°C to a far lesser extent than theoretically calculated, to yield five and seven-membered lactones. The polymerization of chloroprene in the presence of EASC and acetonitrile yields a radical homopolymer with trans-1,4 unsaturation.     

Poly(styrene peroxide) and Poly(methyl methacrylate peroxide) for Grafting on Unsaturated Bacterial Polyesters

A new soluble terephthaloyl oligoperoxide (OTP) was synthesized by the reaction of terephthaloyl peroxide and 2,5‐dimethyl 2,5‐dihydroperoxy hexane. Thermal polymerization of vinyl monomers (styrene, methyl methacrylate) with OTP yielded poly(styrene peroxide) (PS‐P) and poly(methyl methacrylate peroxide) (PMMA‐P) which are used in the grafting reactions onto medium chain length unsaturated bacterial polyester obtained from soybean oily acids with Pseudomonas oleovorans poly(3‐hydroxy alkanoate), (PHA). PS‐g‐PHA and PMMA‐g‐PHA graft copolymers isolated from related homopolymers were characterizated by ¹H NMR spectrometry, FT‐IR spectroscopy, thermal analysis and gel permeation chromatographic (GPC) techniques. Swelling measurement of the crosslinked graft copolymers were also measured to calculate q_v values.     

New initiator system for the anionic polymerization of (meth)acrylates in toluene. IV. Random copolymerization of (meth)acrylates in toluene initiated by s-BuLi ligated by lithium silanolates

Copolymerization of binary mixtures of alkyl (meth)acrylates has been initiated in toluene by a mixed complex of lithium silanolate  (s-BuMe₂SiOLi) and s-BuLi (molar ratio > 21) formed in situ by reaction of s-BuLi with hexamethylcyclotrisiloxane (D₃). Fully acrylate and methacrylate copolymers, i.e., poly(methyl acrylate-co-n-butyl acrylate), poly(methyl methacrylate-co-ethyl methacrylate), poly(methyl methacrylate-co-n-butyl methacrylate), poly(methyl methacrylate-co-n-butyl methacrylate), poly(isobornyl methacrylate-co-n-butyl methacrylate), poly(isobornyl methacrylate-co-n-butyl methacrylate) of a rather narrow molecular weight distribution have been synthesized. However, copolymerization of alkyl acrylate and methyl methacrylate pairs has completely failed, leading to the selective formation of homopoly(acrylate). As result of the isotactic stereoregulation of the alkyl methacrylate polymerization by the s-BuLi/s-BuMe₂SiOLi initiator, highly isotactic random and block copolymers of (alkyl) methacrylates have been prepared and their thermal behavior analyzed. The structure of isotactic poly(ethyl methacrylate-co-methyl methacrylate) copolymers has been analyzed in more detail by Nuclear Magnetic Resonance (NMR). © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2525–2535, 1999     

Synthesis of Amphiphilic Graft Copolymers with Poly(2‐methyl‐2‐oxazoline) Side Chains and a Backbone Containing Chloromethylstyrene and Methyl Methacrylate

New amphiphilic graft copolymers were synthesized by means of a cationic ring‐opening polymerization of 2‐methyl‐2‐oxazoline initiated with a statistical copolymer of methyl methacrylate and chloromethylstyrene. The synthesis was carried out in benzonitrile at 110°C. The grafting reaction was quantitative and the yield of grafting was more than 90%percent;. The graft copolymers were characterized by means of NMR, FT‐IR, and UV‐VIS spectroscopy, as well as elemental analysis and viscosity measurements of their aqueous solutions. The graft copolymers revealed amphiphilic properties and evidence for the formation of micelles and molecular aggregates in aqueous solution. Graft copolymers with relatively short lateral chains are soluble in methanol but insoluble in water, while the copolymers with longer lateral chains are soluble in both methanol and water.     

Heteroarm Star‐Like Micelles Formed from Polystyrene‐block‐poly(2‐vinyl pyridine)‐block‐poly(methyl methacrylate) ABC Triblock Copolymers in Toluene

Polystyrene‐block‐poly(2‐vinyl pyridine)‐block‐poly(methyl methacrylate) ABC triblock copolymers were synthesized by sequential living anionic polymerization. Their solution properties were investigated in toluene, which is a bad solvent for the middle block. Spherical micelles are formed, which consist of a poly(2‐vinyl pyridine) dense core bearing polystyrene and poly(methyl methacrylate) soluble chains at the corona. These micelles exhibit the architecture of heteroarm star copolymers obtained by “living” polymerization methods. The aggregation numbers strongly depend on the length of the insoluble P2VP middle block, thus remarkably affecting the size of the micelles.     

Polymerization of methyl methacrylate and styrene in the presence of polyimides containing aliphatic moieties in the backbone

The radical homopolymerization of methyl methacrylate and styrene in the presence of polyimide that contains aliphatic moieties and is dissolved in the monomer is studied. The viscosity characteristics, heat resistances, and thermal stabilities of the resulting polymers and their solubilities in organic solvents are examined. It is found that the products of radical polymerization are polyimide-poly(methyl methacrylate) and polyimide-polystyrene copolymers, whose properties differ from those of the respective unmodified polymerization and polycondensation polymers.     

Formation and flocculation of graft copolymer micelles

Criteria for formation and flocculation of micelles from pure graft copolymers were investigated in single selective solvents by turbidimetry with the use of two series of graft copolymers from poly(vinyl acetate) (PVAC), i.e., PVAC–styrene graft copolymers with one branch and PVAC–methyl methacrylate graft copolymers with one and several branches. These graft copolymers could be completely coagulated through two processes in the selective solvents which had widely different ? temperatures. The first process is the formation of micelles. One sequence, i.e., either backbone or branch of the graft copolymers, becomes desolvated under conditions similar to those for the corresponding homopolymer. This results in formation of the core of the micelle, the other soluble sequence extending from the surface of the core into the solvent phase. As the soluble chains cover the micelle core, no macroscopic phase separation occurs, but a stable dispersion is formed. The second process is that the micelle becomes too unstable to exist as dispersed when the solvency of the medium for the soluble sequence decreases to a certain degree. As a result, flocculation of the micelle finally takes place.     

Copolymerization of Styrene and Methyl Methacrylate with Lithium as Initiator

Copolymers of styrene and methyl methacrylate prepared with lithium dispersion as initiator do not contain random sequences of both monomers. Fractionation of the copolymers with acetonitrile and the NMR spectra of the insoluble fractions show that these are block copolymers which consist of a polystyrene portion and a poly(methyl methacrylate) portion. When the copolymerization is stopped at low conversion the copolymer has a high styrene content, which sometimes exceeds the value expected for radical copolymerization. This fact would indicate that styrene is preferentially polymerized at the early stages of chain propagation. When the copolymerization is carried to high conversion some crosslinked polymer is formed which contains more styrene than the soluble part of the same experiment. When a piece of metallic lithium is used as initiator, it is found that the crosslinked polymer is formed on the surface of the metal. The addition of lithium phenoxide or β-naphthoxide to the system eliminates the formation of crosslinked polymer. A possible mechanism is proposed.     

Use of the Pauson–Khand reaction products as monomers in the palladium(II)‐catalyzed homopolymerization and copolymerization of norbornene derivatives

New norbornene derivatives synthesized from Pauson–Khand reaction products were homopolymerized and copolymerized with norbornene with an allyl–palladium complex as a catalyst. The ketone group was tolerated by the polymerization reaction. Monomers bearing protected alcohols were easily homopolymerized. Most of the homopolymers were soluble in tetrahydrofuran, CH₂Cl₂, toluene, and cyclohexane. As the steric bulkiness of the substituent increased, the chain length of the homopolymer decreased. Copolymers with a molecular weight of up to 153,800 were formed and were soluble in tetrahydrofuran, CH₂Cl₂, toluene, and diethyl ether. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 76–83, 2003     

Fluorine‐containing linear block terpolymers: Synthesis and self‐assembly in solution

Linear triblock terpolymers of poly(n‐butyl methacrylate)‐b‐poly(methyl methacrylate)‐b‐poly(2‐fluoroethyl methacrylate) (PnBMA‐PMMA‐P2FEMA) were synthesized by sequential reversible addition fragmentation chain transfer (RAFT) polymerization. Kinetic studies of the homopolymerization of 2FEMA by RAFT polymerization demonstrated controllable characteristics with fairly narrow polydispersities (～1.30). The resultant PnBMA‐PMMA‐P2FEMA triblock terpolymers were characterized via ¹H NMR, ¹⁹F NMR, and gel permeation chromatography. These polymers formed micellar aggregates in a selective solvent mixture. The as‐formed micelles were analyzed using scanning electron microscopy and dynamic light scattering. It was found that these terpolymers could directly self‐organize into complex micelles in a tetrahydrofuran/methanol mixture with diameters that depended on polymer composition. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Surface modification of polystyrene latex particles via atom transfer radical polymerization

The atom transfer radical polymerization (ATRP) technique using the copper halide/ N,N′,N′,N″,N″‐pentamethyldiethylenetriamine complex was applied to the graft polymerization of methyl methacrylate and methyl acrylate on the uniform polystyrene (PS) seed particles and formed novel core‐shell particles. The core was submicron crosslinked PS particles that were prepared via emulsifier‐free emulsion polymerization. The crosslinked PS particles obtained were transferred into the organic phase (tetrahydrofuran), and surface modification using the chloromethylation method was performed. Then, the modified seed PS particles were used to initiate ATRP to prepare a controlled poly(methyl methacrylate) (PMMA) and poly(methyl acrylate) (PMA) shell. The final core‐shell particles were characterized using Fourier transform infrared spectroscopy, nuclear magnetic resonance, scanning electron microscopy, thermogravimetric analysis, and elementary analysis. The grafting polymerization was conducted successfully on the surface of modified crosslinked PS particles, and the shell thickness and weight ratio (PMMA and PMA) of the particles were calculated. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 892–900, 2002; DOI 10.1002/pola.10160     

Functionalization and crosslinking reactions of ethyl-α-hydroxymethylacrylate

Ethyl-α-hydroxymethylacrylate (EHMA) was esterified with hexanoyl chloride in 80% yield. The homopolymer of the hexanoate ester was found to be a glassy thermoplastic and soluble polymer. Copolymerization of the hexanoate ester with EHMA in varying ratios gave polymers that were thermoplastic and more soluble as a result of internal lubrication of the long alkyl pendant groups. Copolymers with styrene were synthesized with relatively high conversion. Reaction of EHMA with adipoyl chloride gave a bis-ester which served as crosslinking agent when copolymerized with different monomers including EHMA itself. In a separate synthesis EHMA was reacted with toluenediisocyanate (TDI). In the absence of catalyst a monourethane was formed. This monomer still contains one isocyanate function and is capable of further reactions subsequent to double bond addition polymerization. This reaction was also carried out on poly-EHMA, with or without catalyst. The products were the mono and the crosslinked bisurethanes as expected. Thus, acyl chlorides and isocyanates were found to be excellent reagents for derivatization of EHMA. © 1993 John Wiley & Sons, Inc.