Graft Copolymers Of Polystyrene Research Articles

Enhanced electrical insulating properties of polyethylene by incorporating polyethylene‐g‐polystyrene graft copolymers

AbstractAiming at utilizing the electron energy absorption characteristic of the benzene ring in polystyrene (PS) to enhance the electrical properties of insulation, here linear low density polyethylene grafted PS graft copolymers (LLDPE‐g‐PS) have been synthesized by pre‐irradiation and suspension grafting technology. Then, LLDPE‐g‐PS was added in LLDPE to prepare LLDPE/LLDPE‐g‐PS blends, of which the microstructure and thermal, rheological, electrical and mechanical properties were systematically investigated. Scanning electron microscopy showed that no interfacial debonding occurred in the blends. Rheological measurements showed that the viscoelastic properties of the blends were roughly the same as those of LLDPE. In terms of electrical properties, as LLDPE‐g‐PS was added, the injection of space charges was markedly suppressed. Meanwhile, all blends presented higher DC breakdown strength and the maximum was 1.45 times higher than that of LLDPE. Besides, blends exhibited little change in mechanical properties compared with LLDPE when PS contents were lower than 10 wt%. This investigation proposes an efficient method to improve the electrical properties of insulating materials. © 2020 Society of Industrial Chemistry

Fabrication and electrical study of large area free-standing membrane with embedded GaP NWs for flexible devices

Flexible optoelectronic structures are required in a wide range of applications. Large scale modified silicone-embedded n-GaP nanowire arrays of a record 6 µm thin membranes were studied. A homogeneous silicone encapsulation was enabled by G-coating using a heavy-load centrifuge. The synthesized graft-copolymers of polydimethylsiloxane (PDMS) and polystyrene demonstrated two times lower adhesion to Si compared to standard PDMS, allowing 3 square inch area high quality silicone/nanowire membrane mechanical release, preserving the growth Si substrate for a further re-use after chemical cleaning. The 90% transparent single-walled carbon nanotubes electrical contacts to the embedded n-GaP nanowires demonstrated mechanical and electrical stability. The presented methods can be used for the fabrication of large scale flexible inorganic optoelectronic devices.

Study of nanostructure of polymer adsorption layers on the particles surface of titanium dioxide

The surface modification of titanium dioxide in aqueous dispersions of specially tailor-made periodic acrylic acid/isobutylene copolymers, poly(acrylic acid)/polystyrene graft copolymers, and hydrophobically modified polyethyleneoxide urethane by ultrasonic treatment was studied. The pigment surface modification by the above copolymers was comparatively investigated regarding conventional adsorption as contrasted to an ultrasonic treatment assisted procedure. The course and efficiency of the polymer adsorption onto the pigment surface was quantified by electrokinetic sonic amplitude measurements. The higher efficiency of the pigment surface coating by the copolymers as achieved by ultrasonic treatment varies with the copolymer architecture and is a consequence of ultrasonically induced pigment surface activation.

Ultrasonic Treatment Enhanced Surface Modification of Titanium Oxide by Tailor-Made Surface-Active Polymers

The surface modification of titanium dioxide in aqueous dispersions of specially tailor-made periodic acrylic acid/isobutylene copolymers, poly(acrylic acid)/polystyrene graft copolymers, and hydrophobically modified polyethyleneoxide urethane (HEUR) by ultrasonic treatment was studied. The pigment surface modification by the above copolymers was comparatively investigated regarding conventional adsorption as contrasted to an ultrasonic treatment assisted procedure. The course and efficiency of the polymer adsorpption onto the pigment surface was quantified by electrokinetic sonic amplitude measurements. The higher efficiency of the pigment surface coating by the copolymers as achieved by ultrasonic treatment varies with the copolymer architecture and is a consequence of ultrasonically induced pigment surface activation.

Electron beam radiation grafting of styrene on natural rubber using Taguchi's design

Graft copolymer of natural rubber (NR) and polystyrene was successfully prepared by electron beam irradiation for the first time. The experiments were designed based upon the Taguchi method, using Minitab software, in order to reduce the number of experiments. The radiation dose was varied from 25 to 100 kGy. The content of sensitizer (n-BA) was varied from 0 to 5 phr. Various NR/St ratios were used: 90:10, 80:20, 70:30, and 60:40. Characterization of graft copolymer was confirmed by Fourier transform infrared spectroscopy (FTIR)and transmission electron microscopy (TEM) techniques. The core–shell structure of graft copolymer was obtained and the monomer conversion, grafting efficiency, grafting yield, and crosslink density were studied. Optimum conditions were determined by the experimental design: radiation dose of 75 kGy, content of n-BA of 5 phr, and NR/St ratio of 80:20. Finally, the tensile strength of latex films was found to be significantly related to the studied factors.

Synthesis of poly(ethylene-co-vinyl alcohol)-g-polystyrene graft copolymer and their applications for ordered porous film and compatibilizer

Synthesis of poly(ethylene-<i>co</i>-vinyl alcohol)-<i>g</i>-polystyrene graft copolymer and their applications for ordered porous film and compatibilizer

Preparation of Graft Copolymer of Natural Rubber and Polystyrene by Electron Beam Irradiation

The simultaneous graft copolymerization between natural rubber (NR) and styrene monomer (St) was induced by electron beam irradiation. The grafted polystyrene in graft copolymer was characterized by Fourier Transform Infrared Spectroscopy (FT-IR). This research investigated the influence of three factors (radiation dose, type of emulsifier and adding of sensitizer; normal butyl acrylate (n-BA)). It was found that the appropriated emulsifier was ammonium laurate which lead to higher monomer conversion and grafting efficiency. The adding of n-BA could notably enhance monomer conversion and crosslink density. Moreover increasing radiation dose, the monomer conversion and crosslink density increased. This technique was a cleaner and faster technology suitable for grafting application.

Relationship between branch length and the compatibilizing effect of polypropylene‐g‐polystyrene graft copolymer on polypropylene/polystyrene blends

ABSTRACTThree polypropylene‐g‐polystyrene (PP‐g‐PS) graft copolymers with the same branch density but different branch lengths were evaluated as compatibilizing agents for PP/PS blends. The morphological and rheological results revealed that the addition of PP‐g‐PS graft copolymers significantly reduced the PS particle size and enhanced the interfacial adhesion between PP and PS phases. Furthermore, it is verified that the branch length of PP‐g‐PS graft copolymer had opposite effects on its compatibilizing effect: on one hand, increasing the branch length could improve the compatibilizing effect of graft copolymer on PP/PS blends, demonstrated by the reduction of PS particle size and the enhancement of interfacial adhesion; on the other hand, increasing the branch length would increase the melt viscosity of PP‐g‐PS graft copolymer, which prevented it from migrating effectively to the interface of blend components. Additionally, the crystallization and melting behaviors of PP and PP/PS blends were compared. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40126.

The Strength Properties of Incompatible Polymer Blends Based on Polyamide and Polystyrene

An examination was made of the influence of the concentration of the compatibiliser – a graft copolymer of polystyrene with maleic anhydride – on the compatibility of a polyamide–polystyrene blend in a wide range of ratios. The influence of the length and frequency of distribution of the graft chains of the graft copolymer on the compatibility and deformation and strength properties of the polyamide–polystyrene blend was established.

Synthesis, characterization, and hydrolytic degradation of graft copolymers of polystyrene and aliphatic polyesters

In the present study, a new class of biodegradable graft copolymers of polystyrene (PS) with aliphatic polyester (APE) side chains were synthesized through combination of nitroxide-mediated free radical polymerization (NMRP) and ring-opening polymerization (ROP) with copper (I)-catalyzed ‘click’ chemistry. First, the click component, azido-functional PS (PS-N3) was prepared by copolymerization of styrene and chloromethyl styrene by NMRP followed by the conversion of chlorine groups of the resulting copolymer to azido groups by using NaN3 in N,N-dimethylformamide. Propargyl functional APEs were prepared independently by ROP of lactic acid and glycolic acid using tin octoate in the presence of propargyl alcohol at 130 °C. Finally, PS-N3 was coupled with the resulting polymers by click chemistry to yield graft copolymers (PS-g-poly (L-lactic-co-glycolic acid) [PLLA] and PS-g-PLLGA, respectively). The intermediates and final graft copolymers were characterized by proton nuclear magnetic resonance (1H NMR) and Fourier transform infrared spectral and gel permeation chromatography analyses. The hydrolytic degradation behavior of the obtained graft copolymers in phosphate buffer saline solution were investigated by the weight loss and molecular weight measurements. It is shown that both copolymers undergo slow hydrolytic degradation, PS-g-PGLLA being relatively faster due to the presence of hydrophilic glycolic acid groups in the structure.

The new esterification catalysts and the nature of reactions proceeding at esterification of synthetic naphthenic acids in their presence

There have been synthesized the novel sulfocationites on the basis of graft copolymers of polystyrene with oligostyrene, and their metal-polymer composites based on the titanium-containing compound with the grafted ionic-liquid type ligands. Esterifacation reaction of synthetic naphthen acid (SNA) fraction with heptyl alcohol as a model reaction has been investigated in the presence of the novel sulfocationites and Ti-containing metal-polymer composites on their basis. Structural group content and molecular mass characteristics of primary and end esterification products have been identified using PMR, NMR, IR-spectroscopy and gel-permeation chromotography methods, correspondingly. The results of the investigations carried out show that the esterification reactions of SNA with alcohols are complex process in the course of which the primary esterification reactions, opening of the five-membered cycles in the condensed naphthenic fragments with formation of oxy-ethers and/or oxy-acids, products of their polycondensation, lactone formation as well as decarboxylation reactions take place. The yields of the basic and side products strongly depend on the nature and method of the sulfocationite and their titanium-containing modificates type catalysts preparation.

Blend composition dependence of the compatibilizing efficiency of graft copolymers for immiscible polymer blends

AbstractThis work is concerned with the dependence of the compatibilizing efficiency of graft copolymers on the composition of immiscible polymer blends. A series of graft copolymers of polystyrene (PS) and polyamide 6 (PA6), denoted as PS‐g‐PA6, with different molecular structures were used as compatibilizers. The PS‐g‐PA6 was more efficient for the PS/PA6 (80/20) blend than for the PS/PA6 (20/80) one, indicating that a graft copolymer whose backbone and grafts match the matrix and the disperse phase polymers, respectively, has higher compatibilizing efficiency. This is in disagreement with the literature. Moreover, whatever the blend composition, for PS‐g‐PA6 graft copolymers with the same backbone and the same number of grafts per backbone, the longer the grafts, the higher their compatibilizing and stabilizing efficiency; for a given backbone/graft mass ratio, the longer the grafts and concomitantly the smaller the number of grafts per backbone, the higher the compatibilizing and stabilizing efficiency of the graft copolymer. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers

Synthesis of polar block grafted syndiotactic polystyrenes via a combination of iridium‐catalyzed activation of aromatic CH bonds and atom transfer radical polymerization

AbstractA combination of iridium‐catalyzed CH activation/borylation and atom transfer radical polymerization (ATRP) was used to generate polar graft copolymers of syndiotactic polystyrene (sPS). The borylation at aromatic CH bonds of sPS and subsequent oxidation of boronate ester proceeded without negatively affecting the molecular weight properties and the tacticity of sPS. A macroinitiator suitable for ATRP could be synthesized by the esterification of 2‐bromo‐2‐methylpropionyl bromide and hydroxy‐functionalized sPS. The graft polymerizations of methyl methacrylate and tert‐butyl acrylate from the macroinitiator using ATRP afforded polar block grafted sPS materials, syndiotactic polystyrene‐graft‐poly(methyl methacrylate) (sPS‐g‐PMMA) and syndiotactic polystyrene‐graft‐poly(tert‐butyl acrylate) (sPS‐g‐PtBA). The latter was hydrolyzed to yield an amphiphilic graft copolymer, syndiotactic polystyrene‐graft‐poly(acrylic acid) (sPS‐g‐PAA). The structures of the copolymers were characterized by NMR and FTIR spectroscopies. Size exclusion chromatography and 1H NMR spectroscopy were used to study any changes in the molecular weight properties from the parent polymer. A decrease in the hydrophobicity of the graft copolymers was confirmed by water contact angle measurements. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6655–6667, 2009

Synthesis and characterization of graft copolymers of syndiotactic polystyrene with polybutadiene and 4‐methylstyrene

AbstractThe basic method for synthesizing syndiotactic polystyrene‐g‐polybutadiene graft copolymers was investigated. First, the syndiotactic polystyrene copolymer, poly(styrene‐co‐4‐methylstyrene), was prepared by the copolymerization of styrene and 4‐methylstyrene monomer with a trichloro(pentamethyl cyclopentadienyl) titanium(IV)/modified methylaluminoxane system as a metallocene catalyst at 50°C. Then, the polymerization proceeded in an argon atmosphere at the ambient pressure, and after purification by extraction, the copolymer structure was confirmed with 1H‐NMR. Lastly, the copolymer was grafted with polybutadiene (a ready‐made commercialized unsaturated elastomer) by anionic grafting reactions with a metallation reagent. In this step, poly(styrene‐co‐4‐methylstyrene) was deprotonated at the methyl group of 4‐methylstyrene by butyl lithium and further reacted with polybutadiene to graft polybutadiene onto the deprotonated methyl of the poly(styrene‐co‐4‐methylstyrene) backbone. After purification of the graft copolymer by Soxhlet extraction, the grafting reaction copolymer structure was confirmed with 1H‐NMR. These graft copolymers showed high melting temperatures (240–250°C) and were different from normal anionic styrene–butadiene copolymers because of the presence of crystalline syndiotactic polystyrene segments. Usually, highly syndiotactic polystyrene has a glass‐transition temperature of 100°C and behaves like a glassy polymer (possessing brittle mechanical properties) at room temperature. Thus, the graft copolymer can be used as a compatibilizer in syndiotactic polystyrene blends to modify the mechanical properties to compensate for the glassy properties of pure syndiotactic polystyrene at room temperature. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Synthesis and Characterization of Poly(vinylidene fluoride)-g-sulfonated Polystyrene Graft Copolymers for Proton Exchange Membrane

A series of poly(vinylidene fluoride)-g-sulfonated polystyrene (PVDF-g-SPS) graft copolymers were systematically synthesized and examined with the focus of understanding how the polymer microstructure (backbone molecular weight, graft density, graft length, sulfonic acid concentration, ion exchange capacity, etc.) affects their morphology, water uptake, and proton conductivity under various environmental conditions (temperature and relative humidity). The synthesis of these relatively well-defined graft structures involves three reaction steps, including the preparation of PVDF copolymers containing a few mol% of chlorotrifluoroethylene (CTFE) units, the ATRP graft-from reaction to incorporate several polystyrene side chains, and the subsequent sulfonation reaction on the PS side chains. The PVDF-g-SPS graft copolymer with a combination of a high PVDF backbone molecular weight (Mn >300 000 g/mol), very low SPS graft density (0.3 mol%), and high graft length (SPS content >30 mol%) presents an interesting material for the proton exchange membrane (PEM). This graft copolymer self-assembles into a microphase-separated morphology with randomly oriented long-range lamella/cylinder ionic channels (with small widths) that are imbedded in the hydrophobic semicrystalline PVDF matrix. This graft copolymer morphology offers a high ion exchange capacity (IEC = 2.75 mmol/g) and resistance to excessive water swelling, which yields notably higher proton conductivity than Nafion under 30−120 °C and high humidity conditions.

Preparation of PS‐g‐PA6 copolymers by anionic polymerization of ε‐caprolactam using PS precursors with N‐carbamated caprolactam pendants as macroactivators

AbstractThe graft copolymer of polystyrene and polyamide 6 (PS‐g‐PA6) was investigated by anionic polymerization of ε‐caprolactam (CL), using the free radical copolymer of styrene and a kind of allyl monomer containing N‐carbamated caprolactam group as macroactivator (PS‐CCL). CL monomers were grafted onto PS‐CCL backbone via initiating N‐carbamated caprolactam (CCL) pendants along its backbone to form the graft copolymer in the presence of catalyst sodium caprolactamate. The macroactivator was characterized by Fourier‐transform infrared spectroscopy and nuclear magnetic resonance, and the graft copolymer by the selective solvent extraction technique using methanol and chloroform as solvents. PS‐g‐PA6 copolymers with different PS content were synthesized to study the effect of PS on morphology, crystallinity, dimensional stability, and thermal properties, using scanning electron microscopy, X‐ray diffraction, water absorption measurement, thermogravimetric analysis, and differential scanning calorimetry. The results show the percentage crystallinity of graft copolymer decreases with increasing PS content, but the addition of PS scarcely influences the crystalline structure of PA6. The graft copolymer has improved thermal properties and dimensional stability. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Mechanism of graft copolymerization of styrene onto deproteinized natural rubber

High conversion and high grafting efficiency attained by graft copolymerization of styrene onto deproteinized natural rubber (DPNR) was investigated with respect to the molecular weight of grafted polystyrene. The graft copolymerization was performed with tert-butyl hydroperoxide/tetraethylenepentamine as an initiator after deproteinization of natural rubber with urea. Grafted polystyrene was isolated from the resulting graft copolymer by ozonolysis reaction. After the ozonolysis of the graft copolymer of DPNR and polystyrene (DPNR-g-PS), the molecular weight of grafted polystyrene was determined by size exclusion chromatography. Effects of initiator and monomer concentrations were investigated with respect to the molecular weight of the grafted polystyrene, which was found to depend on not only the number of active site generated on the rubber particle but also the feed of styrene. Deactivation and chain transfer of the active sites were attributed to effective amount of styrene used for the graft copolymerization.

Determination of the molar mass of polyamide block/graft copolymers by size-exclusion chromatography at room temperature

The molar mass of polyamides (PAs) can be measured by conventional size-exclusion chromatography (SEC) after they are subjected to the N-trifluoroacetylation reaction with trifluoroacetic anhydride (TFAA), leading to the corresponding N-trifluoroacetylated derivatives (PA-TFAA). This work was aimed at extending the above method to the measurement of the molar mass of polyamide block/graft copolymers and, more specifically, graft copolymers of polystyrene (PS) and polyamide 6 (PA6) with PS as the backbone and (PA6) as grafts, denoted as PS–g–PA6. Unlike a pure PA, the N-trifluoroacetylation reaction of PS–g–PA6 could not proceed in dichloromethane (CH 2Cl 2) alone. A co-solvent had to be used to help dissolve the PS segments of PS–g–PA6. Tetrahydrofuran (THF), toluene and chloroform, three common good solvents of PS, were tested as co-solvents. Only chloroform was suitable for the N-trifluoroacetylation reaction of PS–g–PA6. THF reacted with TFAA. The boiling point of toluene was so high that it could be removed from the copolymer only under vacuum and, at relatively high temperature, the N- N-trifluoroacetyled PS–g–PA6 could be converted back to the initial PS–g–PA6. Dual UV detection at two different wavelengths allowed determining both the molar mass and composition of PS–g–PA6.

Optimized synthesis and characterization of polystyrene graft copolymers and preliminary assessment of their biodegradability and application in water pollution alleviation technologies

With more and more plastics being employed in human lives and increasing pressure being placed on capacities available for plastic waste disposal, the need for biodegradable plastics and biodegradation of plastic wastes has assumed increasing importance in the last few years. Keeping in view the environmental pollution caused by the waste polystyrene and to make the waste polystyrene technologically important, we have modified/functionalized the polystyrene with natural polymers and hydrophilic monomer through graft copolymerization. The present paper discusses the optimum conditions for the synthesis of graft copolymers and characterization of these polymers with SEMs and FTIR and thereafter biodegradation studies of these polymers by soil burial method. The present paper also discusses the effect of crosslinker concentration on the swelling and metal ion sorption (As +5 uptake) through the functionalized polystyrene, with the intention to make use of these polymeric networks in water pollution alleviation technology. It has been observed that percent As 5+ uptake decreases from 80% to 60% as the crosslinker concentration increases from 0.032 mM to 0.162 mM in the polymeric networks. It has also been observed from the degradation studies that the grafting of starch onto polystyrene has induced 37% degradation after 160 days soil burial treatment and no degradation has been observed in case of grafting of acrylic acid onto polystyrene.

Synthesis of syndiotactic-polystyrene- graft-poly(methyl methacrylate) and syndiotactic-polystyrene- graft-atactic-polystyrene by atom transfer radical polymerization

Syndiotactic polystyrene graft copolymers, including syndiotactic-polystyrene- graft-poly(methyl methacrylate) and syndiotactic-polystyrene- graft-atactic-polystyrene, were synthesized by atom transfer radical polymerization (ATRP) using bromoacetylated syndiotactic polystyrene as macroinitiator and copper bromide combined with 2,2′-bipyridine as catalyst. The macroinitiator was prepared from the acid-catalyzed halogenation reaction of partially acetylated syndiotactic polystyrene, which was synthesized in a heterogeneous process with acetyl chloride and anhydrous aluminum chloride in carbon disulfide. The graft copolymers were characterized by 1H- and 13C-NMR spectra.