Graft Copolymers Of Polystyrene Research Articles

Properties of polyurethane–polystyrene graft copolymer membranes used for separating water–ethanol mixtures

Polyurethane prepolymers (PU) based on hydrophilic poly(ethylene glycol) (PEG), hydroxypropyl acrylic acid (HPA), 2,4-toluene diisocyanate (TDI), and butanediol (BDO) were prepared by one-step polymerization with butanediol as the chain extender. Polyurethane–polystyrene graft copolymers (PU-g-PS) were synthesized by free radical copolymerization of PU with styrene (ST), 2,2′-azobisisobutyronitrile (AIBN) was used as initiator and toluene as solvent. Experimental results showed that the crosslinked membranes of PU–PS graft copolymers could be used for separating ethanol–water mixtures. The highest value of the separation factor ( α) of the crosslinked separation membranes can reach 17.3. Scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) were used to characterize the properties of PU–PS crosslinked membranes.

Systematic luminescence studies of polystyrene bearing stilbenoid side chains

Four different series of polystyrene graft copolymers with stilbene moieties in the side chains were synthesised. Two of these series had the side chains attached to the polystyrene backbone through a flexible ether linkage, whereas in the two other series they were attached more rigidly. The UV-VIS absorption and emission spectra were recorded and compared to those of the respective blends of stilbene derivatives in polystyrene. None of the graft copolymers showed aggregate formation in the absorption spectra, but some aggregate emission was observed, particularly at higher loadings.

Preparation of the HIPS/MA graft copolymer and its compatibilization in PA6/HIPS blends

The graft copolymer of high impact polystyrene (HIPS) grafted with malice anhydride (MA) (HIPS-g-MA) was prepared with melt mixing in the presence of a free-radical initiator. The grafting reaction was confirmed by IR analyses and the amount of MA grafted on HIPS was evaluated by a titration method. 1–5 wt% of MA can be grafted on HIPS. HIPS-g-MA is miscible with HIPS. Its anhydride group can react with the PA6 during melt mixing the two components. The compatibility of HIPS-g-MA in the HIPS/PA6 blends was evident. Evidence of reactions in the blends was confirmed in the morphology and mechanical properties of the blends. A significant reduction in domain size was observed because of the compatibilization of HIPS-g-MA in the blends of HIPS and PA6. The tensile mechanical properties of the prepared blends were investigated and the fracture surfaces of the blends were examined by means of the scanning electron microscope (SEM). The improved adhesion in a 16%HIPS/75%PA6 blend with 9%HIPS-g-MA copolymer was detected. The morphology of fibrillar ligaments formed by PA6 connecting HIPS particles was observed.

Preparation of poly(butylene terephthalate)/oxazoline containing polystyrene graft copolymer through melt-blending and their application as a compatibilizer in polycarbonate/polystyrene blend

The polybutylene terephthalate (PBT)/oxazoline containing polystyrene (RPS) graft copolymer was prepared through melt reaction of PBT and RPS. The formation of the PBT/RPS graft copolymer was noticed by the increase in torque during melt blending in a Haake Buchler internal mixer and also confirmed by the observation of Fourier transform infrared spectroscopy (FT-IR) after the extraction of RPS from the PBT/RPS mixture. The compatibilized polycarbonate (PC)/polystyrene (PS) blends with the pre-made PBT/RPS graft copolymer were prepared by melt blending in the internal mixer. The morphologies of these blends were examined by the transmission electron microscope (TEM). The compatibilized PC/PS blends showed finer morphologies than the uncompatibilized blend. Tensile properties of these blends were also investigated.

Wetting Behavior of Graft Copolymer Substrate with Chemically Identical Homopolymer Films

The wetting behavior of deuterated poly(ethyl acrylate) (dPEA) and polystyrene (PS) homopolymers on the substrates of dPEA−PS graft copolymers with different graft chains (dPEA-g-xPS, x = 1, 3, 5, average number of graft chains) was investigated utilizing scanning force microscopy (SFM). The lateral force and adhesion force measurements of dPEA-g-xPS substrates show that the surface molecular mobility of the dPEA-g-xPS substrate with the dPEA outermost layer decreases with the number of graft chains because of their different aggregation structure. As the number of PS grafts increases, the wetting behavior of dPEA on graft copolymer substrates changes from wetting to partially wetting. The contact angle measurement at the dPEA homopolymer/dPEA-g-xPS substrate interface indicates that the substrate with more PS grafts has a higher interfacial tension with the dPEA homopolymer. The wetting behavior of PS homopolymer on the dPEA-g-xPS substrates depends on the viscosity of the substrate, which is expected to...

Multifunctional ATRP initiators: Synthesis of four-arm star homopolymers of methyl methacrylate and graft copolymers of polystyrene and poly(t-butyl methacrylate)

Tetrakis bromomethyl benzene was used as a tetrafunctional initiator in the synthesis of four-armed star polymers of methyl methacrylate via atom transfer radical polymerization (ATRP) with a CuBr/2,2 bipyridine catalytic system and benzene as a solvent. Relatively low polydispersities were achieved, and the experimental molecular weights were in agreement with the theoretical ones. A combination of 2,2,6,6-tetramethyl piperidine-N-oxyl-mediated free-radical polymerization and ATRP was used to synthesize various graft copolymers with polystyrene backbones and poly(t-butyl methacrylate) grafts. In this case, the backbone was produced with a 2,2,6,6-tetramethyl piperidine-N-oxyl-mediated stable free-radical polymerization process from the copolymerization of styrene and p-(chloromethyl) styrene. This polychloromethylated polymer was used as an ATRP multifunctional initiator for t-butyl methacrylate polymerization, giving the desired graft copolymers.

Crystallization of Newly Synthesized Syndiotactic Graft Copolymers

Abstract Crystallization behavior of newly synthesized syndiotactic graft copolymers of polystyrene having side chains of atactic polystyrene (APS) or of polyisoprene were studied. The APS side chains were found to have rather strong effect to prevent crystallization of the main chain of syndiotactic polystyrene.

Macromolecular architecture effects on block copolymer dynamics. II. A2B simple grafts

Photon correlation spectroscopy has been used to investigate the dynamics of composition fluctuations in disordered semidilute solutions of (polyisoprene)2(polystyrene) (I2S) graft copolymers in toluene. Four different relaxation mechanisms were identified with different concentration and wavevector dependencies: Three are the well-known processes in diblock copolymer solutions (cooperative diffusion, internal mode, and polydispersity diffusive mode), whereas the fourth is an extra process between the internal and the polydispersity modes that appears near the disorder-to-order transition. The latter displays similar characteristics to a process recently observed for inverse starblock copolymers also in the ordering region, and should be related to the macromolecular architecture. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 3385–3391, 1999

Syndiospecific copolymerization of styrene with styrene macromonomer bearing terminal styryl group by CpTiCl3–methylaluminoxane catalyst

Copolymerization of styrene with styrene-terminated polystyrene macromonomer (SSTM) by CpTiCl3–methylaluminoxane (MAO) catalyst was investigated. SSTM was prepared by a reaction of living polystyrene initiated with sec-butyllithium (s-BuLi) and p-chloromethyl styrene at −78°C. The synthesized SSTM has a high terminal functionality and a narrow molecular weight distribution. Graft copolymers of polystyrene consisted of syndiotactic main chain and atactic side chain were synthesized by CpTiCl3–MAO catalyst. The synthesized graft copolymer was confirmed to have highly syndiotactic sequence on the main chain.

Preparation of the HIPS/MA graft copolymer and its compatibilization in HIPS/PA1010 blends

The graft copolymer of high-impact polystyrene (HIPS) grafted with maleic anhydride (MA) (HIPS-g-MA) was prepared with melt mixing in the presence of a free-radical initiator. The grafting reaction was confirmed by infrared analyses, and the amount of MA grafted on HIPS was evaluated by a titration method. 1-5% of MA can be grafted on HIPS. HIPS-g-MA is miscible with HIPS. Its anhydride group can react with polyamide 1010 (PA1010) during melt mixing of the two components. The compatibility of HIPS-g-MA. in the HIPS/PA1010 blends was evident. Evidence of reactions in the blends was confirmed in the morphology and mechanical behavior of the blends. A significant reduction in domain size was observed because of the compatibilization of HIPS-g-MA in the blends of HIPS and PA1010. The tensile mechanical properties of the prepared blends were investigated, and the fracture surfaces of the blends were examined by means of the scanning electron microscope. The improved adhesion in a 15% HIPS/75% PA1010 blend with 10% HIPS-g-MA copolymer was detected. The morphology of fibrillar ligaments formed by PA1010 connecting HIPS particles was observed. (C) 1999 John Wiley & Sons, Inc.

Surface-Induced Ordering in Graft Copolymer Thin Films

The surface-induced ordering of deuterated poly(ethylacrylate)-polystyrene (dPEA-PS) graft copolymers with different average number x of graft chains per copolymer chain (dPEA-g-xPS, x = 1, 3, 5) was investigated using neutron reflection, secondary ion mass spectrometry, and atomic force microscopy. The ordering starts only at the vacuum surface and decays through the bulk of the film to the silicon surface. The dPEA-g-3PS thin films (f, fraction of styrene monomers = 0.28) appear to have dPEA-PS lamellar structures and a nearly pure dPEA layer next to the vacuum surface. The dPEA-g-5PS thin films (f = 0.48) are found to be cylindrical except for the top layer, adjacent to the vacuum surface, which is lamellar. On comparison with diblock copolymers, graft copolymers show a phase diagram shift and smaller micelle spacing. The authors find that long-range order in graft copolymers only occurs within {approximately}15 lamellar spacings of the vacuum surface. Linear viscoelasticity of bulk samples reveals that none of the shear-history and low-frequency terminal response complications observed for diblock copolymers are observed for graft copolymers, owing to their lack of long-range order.

Gold nanoparticle synthesis in graft copolymer micelles

An amphiphilic poly(acrylic acid)/polystyrene graft copolymer (PAA-g-PS) has been used to form “nanoreactors” for the synthesis of gold clusters. Such copolymers tend to form stable micelles in non-polar organic solvents where the poly(acrylic acid) chains constitute the core, and the polystyrene chains, the shell. In the present study, the micellar structure of PAA-g-PS in toluene has been demonstrated by dynamic light scattering and transmission electron microscopy (TEM).

Development of novel attachable initiators for atom transfer radical polymerization. Synthesis of block and graft copolymers from poly(dimethylsiloxane) macroinitiators

The synthesis of poly(styrene-dimethylsiloxane) block and graft copolymers is described. Commercially available difunctional poly(dimethylsiloxane) (PDMS) containing either vinylsilyl or hydrosilyl terminal species was reacted with the corresponding hydrosilyl or vinylsilyl attachable initiators containing the benzyl chloride species. The attachment of the initiators to PDMS was achieved by hydrosilation in the presence of a platinum(0) catalyst. The terminal benzyl chloride groups were then used as initiators for atom transfer radical polymerization (ATRP) to produce block copolymers. Using this technique, triblock copolymers consisting of a PDMS centre block and polystyrene terminal blocks were synthesized. A similar process was also used to produce graft copolymers of polystyrene from a PDMS backbone.

Grafting of poly(ethylene oxide) with Schiff's base end group onto chloromethylated polystyrene via Decker-Forster reaction

Amphiphilic graft copolymer of polystyrene (PS) as backbone and poly(ethylene oxide) (PEO) as branch chain was prepared by Decker-Forster reaction. PEO with Schiff's base end group (PEOs) was obtained by ring-opening polymerization of ethylene oxide (EO) initiated with protected potassium aminoethoxide, and then alkylated with chloromethylated polystyrene (c-PS). A graft copolymer with high grafting efficiency was derived by hydrolysis of the above-mentioned product.

Grafting of poly(ethylene oxide) with Schiff's base end group onto chloromethylated polystyrene via Decker-Forster reaction

Amphiphilic graft copolymer of polystyrene (PS) as backbone and poly(ethylene oxide) (PEO) as branch chain was prepared by Decker-Forster reaction. PEO with Schiff's base end group (PEOs) was obtained by ring-opening polymerization of ethylene oxide (EO) initiated with protected potassium aminoethoxide, and then alkylated with chloromethylated polystyrene (c-PS). A graft copolymer with high grafting efficiency was derived by hydrolysis of the above-mentioned product.

A convenient route to poly(methylphenylsilane)‐graft‐polystyrene copolymers

AbstractA graft copolymer of polystyrene on poly(methylphenylsilylene) was conveniently synthesised by using the bromomethyl groups of bromomethylated poly(methylphenylsilylene) as initiating sites for the bulk polymerisation of styrene by an atom transfer radical mechanism.

Studies on Polycarbonate/Polystyrene/Polycarbonate-g-Polystyrene Blends. I. Preparation, Characterization and Properties of Polycarbonate-g-Polystyrene

Polycarbonate (PC)/polystyrene (PS) blend is an immiscible system. The use of copolymers as compatibilizers in blends of immiscible polymers is one approach which is being developed within the larger field of polymer blends and alloys. The methods for preparing PC–PS copolymers are difficult and complicated. In this paper, a new method for preparing PC–PS graft copolymer, PC-g-PS, by radiation grafting is proposed. The structure of the graft copolymer was confirmed by IR spectroscopy. Various factors which can be used to control the reaction have been studied. The molecular weight of the PS graft chain was determined by gel permeation chromatography after degrading the copolymer in aqueous sodium hydroxide and dichloromethane. The thermal properties of the copolymer have also been measured. © 1997 SCI.

Synthesis and characterization of aPP/aPS graft copolymers

Graft copolymers of atactic polypropylene (aPP) and polystyrene (PS) were synthesized and characterized by 13C NMR analysis. The 13C NMR spectra of the grafts exhibited changes with respect to physical blends of identical compositions. The most important occurred in the meso sequences of the aPP blocks of the copolymer. These changes suggest that some grafting took place during the synthesis. SEM micrographs indicate greater interfacial interaction between phases in the copolymers than in the physical blends. Thermal Analysis showed that the Tg of the copolymers is higher than that of the PS homopolymers prepared under the same conditions. This could be the result of an apparent increased in molecular weight caused by the grafting of the aPS into the aPP chains. TGA results indicated that the thermal stability of the copolymer decreases as the aPP content in the copolymer increases.

Use of Organic Copolymers as Compatibilizers for Organic−Inorganic Composites

Random, block, and graft copolymers of polystyrene and poly(4-vinylphenol) were studied as compatibilizers for organic−inorganic composite (OIC) materials. The concept is to use these polymers to reduce the interfacial tension in incompatible OIC materials. This should reduce the particle size of the dispersed inorganic phase and improve adhesion between the components, resulting in better optical and mechanical properties. Dynamic mechanical and ultimate physical properties, as well as transmission electron micrographs, are provided as evidence for the compatibilization of polystyrene and titania produced in situ. These results clearly show that the domain size of the dispersed phase can be reduced and the mechanical properties improved with compatibilizers. Perhaps surprisingly, poly(4-vinylphenol) homopolymer was also found to be an effective compatibilizer in polystyrene−titania composites. An alternate compatibilization mechanism is proposed for the homopolymer.

Polystyrene-Poly(Vinylphenol) Copolymers as Compatibilizers for Organic-Inorganic Composites

Random, graft, and block copolymers of polystyrene (PS) and poly(4-vinylphenol) (PVPh), and PVPh homopolymer are shown to act as compatibilizers for incompatible organic-inorganic composite materials. The VPh component reacts, or interacts strongly with the polymerizing inorganic (titanium or zirconium) alkoxide. The organic components studied were PS, poly(vinyl methyl ether), and poly(styrene-co-acrylonitrile). The use of such compatibilizers provides a means of combining in situ polymerized inorganic oxides and hydrophobic polymers. This is seen as a reduction in the size of the dispersed inorganic phase and results in improved optical and mechanical properties.