Polystyrene Macromonomers Research Articles

Perfectly Alternating Amphiphilic Poly(p-phenylene) Graft Copolymers by Combination of Controlled Radical Polymerization and Suzuki Coupling Processes

The preparation of amphiphilic poly(p-phenylene) (PP) possessing completely and perfectly alternating hydrophilic poly(ethylene oxide) (PEO) and hydrophobic polystyrene (PS) side chains is described. First, PS macromonomer with suitable functionality for polyphenylation was prepared by atom transfer radical polymerization (ATRP). The antagonist macromonomer, PEO, was synthesized by etherification reaction. Both macromonomers were reacted in the final stage via Suzuki cross coupling in the presence of Pd(PPh3)4 as catalyst to form the desired amphiphilic graft copolymer (Mn: 32 400 g/mol and Mw/Mn: 2.28). The intermediates obtained in various stages and graft copolymers were characterized by 1H NMR and IR analysis. The optical absorption properties of the polymer were monitored with UV, and an additional absorption at around 280−320 nm evidenced the formation of PP chain. Thermal properties of PP were investigated by DSC. The thermogram displayed two transitions at 51.98 and 89.60 °C, indicating the presen...

Multibranched Polycarbonates Synthesized via Interfacial Polycondensation using Uniform Size Hemi-Telechelic Polystyrene Macromonomers having a Dihydroxyphenyl End-Group

Multibranched polycarbonates with uniform size polystyrene side-groups were obtained by means of hemitelechelic polystyrene macromonomers having a 2,5-dihydrobenzyl end-group. Polystyrene pre-polymers for macromonomers having a methoxy-protected dihydroxyphenyl group were synthesized through ATRP method with 2,5-dimethoxybenzyl bromide as an initiator. After deprotection by dealkylation of the methoxy group, we obtained polystyrene macromonomers. Preparation of the corresponding polycarbonate bearing polystyrene side-chains was conducted via interfacial polycondensation of bisphenol A and bisphenol A bis(chloroformate) in the presence of the macromonomers. DSC measurements of the obtained multibranched polymers showed two glass transition temperatures derived from polystyrene and polycarbonate, which indicated the phase-separated morphology of the bulk film.

Synthesis and characterization of cyclohexene oxide functional polystyrene macromonomers by ATRP and their use in photoinitiated cationic polymerization

In this study, a novel well-defined macromonomer of epoxy end-functionalized polystyrene was synthesized by atom transfer radical polymerization (ATRP). The compound 3-cyclohexenylmethyl-2-bromopropanoate was synthesized by the condensation of 3-cyclohexene-1-methanol with 2-bromopropanoyl bromide. Subsequently, the epoxidation of the obtained 3-cyclohexenylmethyl-2-bromopropanoate using 3-chloroperoxybenzoic acid results in a new epoxy functional ATRP initiator. The ATRP of styrene (St) in bulk at 110 °C, by means of this initiator in conjunction with the cuprous complex Cu(I)Br/bipyridine, yields a well-defined macromonomer of polystyrene with an epoxy end group. GPC, IR, and 1H NMR analyses revealed that a low-polydispersity polystyrene with the desired functionality at the end of the chain was obtained. The photoinduced cationic polymerization of this macromonomer yielded graft and block copolymers.

Synthesis of Syndiotactic Polystyrene Macromonomers End Capped with Bromine Atoms: a Tool for a New Investigation of Styrene Polymerization Mechanism Catalyzed by Monocyclopentadienyl Titanium Compounds

Syndiotactic polystyrene samples end capped with bromine atoms in benzylic position have been synthesized by terminating the syndiospecific styrene polymerization catalyzed by Cp*TiBn3/B(C6F5)3/Al-Oct3 (Cp* = η5-C5(CH3)5; Bn = CH2Ph, Oct = (CH2)7CH3) with N-bromosuccinimide (NBS) and 2-bromo-2-phenylethylisocyanate (BPEI). The chemical structure of the different polymer end groups was assessed by mono and bidimensional NMR techniques. The evaluation of the relative concentrations of the end groups permitted to give new insights into the bromination reaction and syndiospecific styrene polymerization mechanism. Aspecific bromination of the methine carbon of the growing polymer chain bound to the titanium catalyst was observed when NBS was used as terminating agent. The formation of Ti(III) hydrido complexes in the activation reaction was proved as well as the role of these species as active catalyst in syndiospecific styrene polymerization.

Novel Polyolefins Containing Crystallizable Isotactic Polystyrene Side Chains

AbstractVinyl‐terminated isotactic polystyrene macromonomers were copolymerized with ethylene and 1‐octene to new polyolefin graft copolymers with crystallizable polystyrene side chains. The iPS content was varied from 4 to 78 wt.‐% using different metallocene and halfsandwich catalysts. No solubility problems of the stereoregular macromonomer occured, because iPS does not crystallize during polymerization. In addition the polymers show nanophase separation of the polyolefin backbone and the iPS side chains. The crystallization of iPS, having a melting point of about 200 °C, can be achieved by annealing. This synthesis strategy allows the fabrication of a new class of thermoplastic elastomers with improved heat distortion temperatures.magnified image

Synthesis of graft copolymers with “V‐shaped” and “Y‐shaped” side chains via controlled radical and anionic polymerizations

AbstractA combination of nitroxide‐mediated radical polymerization and living anionic polymerization was used to synthesize a series of well‐defined graft (co)polymers with “V‐shaped” and “Y‐shaped” branches. The polymer main chain is a copolymer of styrene and p‐chloromethylstyrene (PS‐co‐PCMS) prepared via nitroxide‐mediated radical polymerization. The V‐shaped branches were prepared through coupling reaction of polystyrene macromonomer, carrying 1,1‐diphenylethylene terminus, with polystyryllithium or polyisoprenyllithium. The Y‐shaped branches were prepared throughfurther polymerization initiated by the V‐shaped anions. The obtained branches, carrying a living anion at the middle (V‐shaped) or at the end of the third segment (Y‐shaped), were coupled in situ with pendent benzyl chloride of PS‐co‐PCMS to form the target graft (co)polymers. The purified graft (co)polymers were analyzed by size exclusion chromatography equipped with a multiangle light scattering detector and a viscometer. The result shows that the viscosities and radii of gyration of the branched polymers are remarkably smaller than those of linear polystyrene. In addition, V‐shaped product adopts a more compact conformation in dilute solution than the Y‐shaped analogy. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4013–4025, 2007

Architecture of Prototype Copolymer Brushes by Grafting-from ATRP Approach from Functionalized Alternating Comb-Shaped Copolymers

Atom transfer radical polymerization (ATRP) was applied to a novel synthesis of prototype copolymer brushes. The procedure included the following steps: (1) free-radical copolymerization of vinylbenzyl-terminated polystyrene (PS-VB) macromonomer and N-(4-hydroxyphenyl)maleimide gave well-defined alternating comb-shaped copolymers, (2) subsequent esterification reaction [N-(4-hydroxyphenyl)maleimide sites] of such comb-shaped copolymer with 2-bromoisobutyryl bromide yielded a comb-shaped polyinitiator, and (3) the grafting-from ATRP method of methyl methacrylate (MMA) using comb-shaped polyinitiator provided PS/poly(methyl methacrylate) (PMMA) alternating copolymer brushes. Dilute solution properties and morphological results of both comb-shaped polyinitiator and prototype copolymer brushes were investigated by static and dynamic light scattering and transmission electron microscopy. As a result, prototype copolymer brush composed of short aspect ratio changed the shape from ellipsoid to starlike conforma...

Poly(propylene-g-styrene) Graft Copolymers with Well-Defined Microstructure by Metallocene Catalyzed Copolymerization of Propylene with Allyl-Terminated Polystyrene Macromonomers

The synthesis of well-defined poly(propylene-g-styrene) (PP-g-PS) graft copolymers was investigated by metallocene catalyzed copolymerization of propylene and allyl-terminated polystyrene macromonomer (PS-allyl) obtained via quasiliving atom transfer radical polymerization (ATRP) and subsequent carbocationic allylation. It was found that the structural parameters of PP-g-PS can be controlled in a broad range by the variation of reaction conditions. At low conversion the number of polystyrene side chains per 1000 propylene units is proportional to the feed concentration of the PS-allyl macromonomer, while the length of polypropylene backbone decreases with increasing feed concentration. The number-average molecular weight (Mn) of PS-allyl determines the side chain length, but it also affects the side chain density and backbone length. Both decrease with increasing Mn of the macromonomer. At constant pressure, by ensuring the constant concentration ratio of propylene to PS-allyl, the PP backbone length can be varied by alteration of temperature while the side chain density remains nearly uniform. This semicombinatorial library of structural parameters vs reaction conditions affords designed synthesis of PP-g-PS graft copolymers with predetermined structure, that is, with desired length of the PS side chains, grafting density, and length of the PP backbone.

Anionic Living Polymerization of Macromonomers: Preparation of (A)n-star-(B)1Star Block Copolymers and Some Properties of the Products Obtained

(4-Vinylbenzyl)polystyrene macromonomer (PStM, Mn = 5.45 × 103, Mw/Mn = 1.03) was living-anionically polymerized by sec-BuLi to produce the (PSt)n- star polymer under high vacuum at room temperature. Then, isoprene (Is) was sequentially copolymerized by (PSt)n- to yield the (PSt)6.1-s-(PIs)1 star block copolymer (Mn = 6.39 × 104, Mw/Mn = 1.04) having a narrow PIs composition distribution. Similarly, the (PIs)6.6-s-(PSt)1 star block copolymer (Mn = 10.8 × 104, Mw/Mn = 1.04) was prepared using (4-vinylbenzyl)polyisoprene macromonomer (PIsM, Mn = 5.19 × 103, Mw/Mn = 1.04). The synthetic route by which the PIs- carbanions copolymerize PStM was found to be unsuitable for preparing (PIs)1-star-(PSt)n. The resultant star polymers and star block copolymers were characterized by a special analysis using a gel permeation chromatograph equipped with a low-angle laser light-scattering detector. The living mechanism of the macromonomers polymerization was discussed from the viewpoint of initiation efficiency. The asym...

マクロモノマーのアニオンリビング重合により合成された星型高分子の腕鎖数分布

From a number fraction (nf) of the number of arms (f) for (PSt)f star polymers prepared via anionic living polymerization of polystyrene macromonomers (PStM), the distribution in number of arms, (f∼nf) has been determined. From a number fraction of polymer (Nf, i) having a degree of polymerization (i), each distribution in a degree of polymerization of (PSt)f, (i∼Nf, i) was first calculated using Nf, i=∑i=j+k (N(f-1), jN1, k) and (i∼N1, i) of the PStM, and then the distribution in a degree of polymerization of (PSt)<f>, (i∼N<f>, i)cal was calculated by N<f>, ical=∑fnfNf, i, where <f> is an average number of arms. By comparing the resultant (i∼N<f>, i)cal with (i∼N<f>, i)obs determined by GPC equipped with a low-angle laser light-scattering detector, each (f∼nf) of the five (PSt)f star polymers was determined. From the polymerization time dependence of the resultant (f∼nf) and polymerization conditions, a non-linear polymerization rate constant and its mechanism were discussed.

Synthesis and Characterization of ABC-type Star and Linear Block Copolymers of Styrene, Isoprene, and 1,3-Cyclohexadiene

Mikto three-arm, ABC-type star copolymers of styrene, isoprene, and 1,3-cyclohexadiene were synthesized by anionic polymerization using 1,3-bis(1-phenylvinyl)benzene (MDDPE) as linking precursor. A polystyrene macromonomer was prepared by monoaddition of polystyryllithium toward MDDPE. The resulting macromonomer was coupled with polyisoprenyllithium through the remaining double bond in MDDPE moiety, forming a diblock copolymer of styrene and isoprene. The diblock copolymer possessed a living center of diphenylethyllithium, which subsequently initiated the polymerization of a small amount of isoprene (“seeding”) and 1,3-cyclohexadiene. It was found that, without the “seeding” process, diphenylethyllithium was not able to initiate the polymerization of 1,3-cyclohexadiene. The resulting macromonomer and star polymers were characterized by gel permeation chromatography, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and 1H NMR spectroscopy. In addition, linear ABC-type triblock copolymers of the corresponding monomers with different sequences were also synthesized. Microphase separation of the linear and star copolymers was investigated by differential scanning calorimetry and transmission electron microscopy.

Design of new poly(ethylene) based materials by coordination (co)polymerization of macromonomers with ethylene

AbstractThe present work discusses first the homopolymerization of ω‐allyl, ω‐undecenyl or ω‐vinylbenzyl polystyrene (PS) macromonomers in the presence of selected early or late transition metal catalysts. Homopolymerization degrees were found to depend on the type of catalyst, the terminal double bond, the polymerization temperature and the concentration of the various species. Higher molar masses were reached at low temperatures and low catalyst and cocatalyst concentrations. Best results were obtained with the constrained geometry catalyst (CGC)‐Ti.The same PS macromonomers were copolymerized with ethylene in the presence of the VERSIPOLTM catalyst to design a new type of poly(ethylene) based graft copolymer. The macromonomer weight percent content decreases with increasing ethylene pressure whereas the molar mass of the copolymer increases with ethylene pressure. The PS macromonomer content as well as the molar mass of the copolymer can be still increased by using α,ω‐difunctional PS macromonomers. The dilute solution and solid‐state behavior of these copolymers were examined and compared to those of poly(ethylenes) prepared under the same conditions. Copyright © 2006 John Wiley &amp; Sons, Ltd.

HyperMacs. Long Chain Branched Analogues of Hyperbranched Polymers Prepared by the Polycondensation of AB2 Macromonomers

AbstractWe describe here a new strategy for the synthesis of polymers with highly branched architectures. The strategy involves the synthesis by anionic polymerization of well‐defined AB2 polystyrene macromonomers with molecular weights from 3,600 to 94,000 gmol−1, which are then converted via a one‐pot polycondensation reaction into high molecular weight, long‐chain (hyper)branched architectures. Since the Hyperbranched structures are built up from condensation Macromonomers we have coined the term ‘HyperMac’ to describe these branched polymers. In this paper we report the synthesis of the HyperMacs, the optimal conditions for the polycondensation reaction and some preliminary characterization studies.

Ordered Microporous Surface Films Formed by Core-Shell-Type Nanospheres

Summary: Polymer nanospheres are synthesized by free-radical dispersion copolymerization of methyl methacrylate (MMA) and ethylene glycol dimethacrylate (EGDM) with a methacryloyl-terminated polystyrene (PS-MC) macromonomer in cyclohexane. Such polymer nanospheres are stabilized sterically with polystyrene (PS)-grafted chains in cyclohexane at temperatures greater than 34 °C (the Θ temperature for PS). Ordered microporous surface films are constructed by casting these core-shell-type nanospheres from hot cyclohexane solution at 20 °C. The results indicate the possibility of fixation or encapsulation of functional materials after microporous patterning of the core-shell-type nanospheres. SEM photograph of a vertical section of a hexagonal micropore film obtained here.

New Materials Designed by Coordination Polymerization of ω‐undecenyl Macromonomers

AbstractThe major part of the present paper discusses the ability of well‐defined ω‐undecenyl polystyrene, polyisoprene or poly(styrene‐block‐isoprene) macromonomers to undergo coordination homopolymerization in the presence of selected titanium catalysts. Special emphasis is given to the influence of the nature of the catalyst, the polymerization temperature and the macromonomer molar mass and concentration on homopolymerization yield and average degree of homopolymerization (DPn). Titanium‐based catalytic systems such as CpTiCl3/MAO and Cp*TiCl3/MAO only yielded dimers. The use of the homogeneous metallocene catalyst with constrained ligand geometry (CGC‐Ti/MAO) having an open active site, significantly improved the degree of polymerization. Increasing macromonomer molar mass, causes only a slight decrease of DPn whereas conversion increased moderately. The final section briefly discusses the copolymerization of ω‐undecenyl polystyrene macromonomers with ethylene in the presence of Versipol™ catalysts.

Efficient Synthesis of ω-(p-Vinylbenzyl)polystyrene by Direct Functionalization of Poly(styryl)lithium with p-Vinylbenzyl Chloride in Hydrocarbon Solvent with Lithium 2,3-Dimethyl-3-pentoxide

The direct functionalization of poly(styryl)lithium (Mn ≈ 2000 g/mol) with p-vinylbenzyl chloride (VBC) has been investigated in hydrocarbon solvent. With a 9-fold excess of VBC and normal addition, the predominant product (55% yield) was the corresponding head-to-head dimer; the macromonomer was formed in only 20% yield as determined by 1H NMR analysis. MALDI-TOF MS analysis of the products showed that the other major side reaction products resulted from addition of PSLi to the vinyl group of VBC. However, in the presence of excess lithium halides (LiCl, LiBr) the amount of dimer formation was reduced (30%), but the yield of macromonomer was increased only slightly (27%). The principal impurity was the corresponding nonfunctional polystyrene attributed to hydrogen abstraction from VBC by PSLi. A high yield (≥98%) of ω-(p-vinylbenzyl)polystyrene macromonomer was obtained when the functionalization was effected in the presence of 10 equiv of lithium 2,3-dimethyl-3-pentoxide. No dimer formation was observed...

Design of new styrene enriched polyethylenes via coordination copolymerization of ethylene with mono- or α,ω-difunctional polystyrene macromonomers

ω-Allyl, ω-undecenyl and α,ω-undecenyl polystyrene macromonomers, well defined in molar mass and functionality, were synthesized via anionic polymerization. Their coordination copolymerization with ethylene with a cationic α-diimine palladium catalyst [ ( ArN = C ( Me ) – C ( Me ) = NAr ) Pd ( CH 2 ) 3 ( COOMe ) ] + BAr 4 ′ − , (Ar=2,6- iPr 2–C 6H 3 and Ar′=3,5-(CF 3) 2–C 6H 3) affords access to a new type of graft copolymers constituted of a polyethylene backbone and polystyrene grafts. It was shown that the environment of the terminal double bond of the PS macromonomers has a huge influence on the polymerization behavior. Indeed, an undecenyl end-group is more reactive than an allyl end-group. The copolymerization of ethylene with α,ω-undecenyl polystyrene macromonomers lead to cross-linking for long polymerization time (18 h at 25 °C). The influence of several parameters (polymerization temperature, ethylene pressure, concentration) on molar masses and macromonomer incorporation yield was also investigated. Macromonomers having the lowest molar masses were the most reactive. The molar mass of the copolymer increased with ethylene pressure. As expected with such a chain walking catalyst, the copolymers presented moderately branched to highly branched structures depending on the ethylene pressure, like for the homopolymerization of ethylene. Finally, rheological investigations of the copolymers showed that a few percentage of polystyrene incorporation can change drastically the mechanical properties of the materials.

Anionic living polymerization of macromonomers: Preparation of a particle-like purging reagent and characterization of poly(macromonomer)s

A cross-linked polystyrene particle (Merrifield resin, R–C 6H 5) was reacted with benzoyl chloride in nitrobenzene to produce R–C 6H 4–COC 6H 5 having a benzophenone group, and the R–C 6H 5–COC 6H 5 was reacted with a sodium mirror in THF under 10 −5 mmHg to produce R–C 6H 5–CO −C 6H 5Na + containing a benzophenone sodium as a particle-like purging reagent (PPBNa). (4-vinylbenzyl)Polystyrene macromonomers (PSM4: M n=4.6 2×10 3, M w/ M n=1.0 3 and PSM7: M n=7.1 0×10 3, M w/ M n=1.0 2) were dried under 10 −6 mmHg for more than 72 h, purified by a special procedure using the PPBNa, and then were living anionically polymerized by sec-BuLi in benzene or n-BuLi in tetrahydrofuran to produce the corresponding poly(PSM) n star polymers. The resultant star polymers were characterized by gel permeation chromatography equipped with low-angle laser light-scattering (GPC-LALLS), membrane osmometry (OSM), and light-scattering (LS). Anionic living polymerization of the PSM macromonomers was confirmed by the fact that the molecular weight of the poly(PSM) n increased and by the fact that the initiation efficiency was constant despite an increase in the polymer yields. Some solution properties and specific dimensions characteristic to the poly(PSM) n star polymers are discussed by comparing the GPC-LALLS, OSM, and LS results for those polymers with the results for linear polystyrenes.

Synthesis and Characterization of Thermally Curable Benzoxazine‐Functionalized Polystyrene Macromonomers

AbstractSummary: Thermally curable benzoxazine ring‐containing polystyrene macromonomers were synthesized and characterized. 1,4‐Dibromo‐2,5‐bis(bromomethyl)benzene and 1,4‐dibromo‐2‐(bromomethyl)benzene were used as initiators in the atom transfer radical polymerization of styrene. The resulting polymers were used in combination with 3‐aminophenylboronic acid hemisulfate, for a Suzuki coupling. The obtained polymers, with amino groups in the middle or end of the chains, were reacted with formaldehyde and phenol to yield benzoxazine ring‐containing macromonomers. In addition to the glass transition temperature of the polystyrene segment observed at ca. 105 °C, differential scanning calorimetry thermograms exhibit an exotherm at ca. 276 °C corresponding to the oxazine thermal polymerization. Both macromonomers undergo thermal curing with the formation of thermosets having polystyrene segments.Structure of the benzoxazine‐functionalized polystyrene.magnified imageStructure of the benzoxazine‐functionalized polystyrene.

Synthesis and characterization of (star polystyrene)- block-(polyisoprene)- block-(star polystyrene) copolymers

A (star polystyrene)- block-(linear polyisoprene)- block-(star polystyrene) copolymer, (S) nI(S) n, was prepared. The star polystyrene was produced via anionic polymerization of polystyrene macromonomers each containing an unsaturated double bond (vinyl) at the chain end. This vinyl-terminated polystyrene macromonomer (SSTM) was obtained beforehand via the synthesis of a living polystyrene using alkyllithium and the termination with p-chloromethylstyrene (PCMS). The living site in the core of the star polystyrene enabled the construction of the succeeding polyisoprene block resulting in the living (star polystyrene)- block-(linear polyisoprene) copolymer, (S) nI. This living diblock copolymer was then coupled with 1,2-dibromoethane (DBE) to form the well-defined (S) nI(S) n. Compared to a linear polystyrene- block-polyisoprene- block-polystyrene, SIS, with the same molecular weight, (S) nI(S) n had a higher T g and exhibited a lamellae-forming phase separation in conjunction with many dislocation defects. The thermal stability appeared independent of the molecular structure, and the radius of gyration and viscosity of (S) nI(S) n were much smaller than SIS.