Synthesis of amphiphilic graft copolymers of SBS with acrylamide and study of their properties

Graft copolymerization of SBS in the form of sodium ionomer with acrylamide in emulsion using benzoyl peroxide as initiator and sodium ionomer of maleated SBS as a self‐emulsifier, which can form a stable cyclohexane/water emulsion with AM without using any other emulsifier, was carried out. Factors affecting the graft copolymerization were studied. The grafting % can reach about 15%. Emulsifying properties of sodium ionomer of maleated SBS and the graft copolymer, as well as the compatibilizing effect of the graft copolymer in blending polyvinyl chloride (PVC) with SBS, were studied. The sodium ionomer of maleated SBS, the graft copolymers, and the blends were characterized with IR and DSC. The results showed that water absorbency and emulsifying volume increase obviously after graft copolymerization with AM. 0.2 g of the graft copolymer containing 14 wt % PAM grafts can emulsify a mixture of 30 mL toluene and 70 mL water completely. The graft copolymer can be used as an effective compatibilizer in the blending of PVC and SBS, more effective than the sodium ionomer of maleated SBS. Only 2 wt % of the copolymer based on the blend used in blending is enough to raise the tensile strength three times. The blends with weigh ratios of PVC/SBS at 3/7–4/6 in the presence of the graft copolymer behave as thermoplastic elastomers with a tensile strength of 14 MPa, an ultimate elongation of 750%, and a permanent set of 17%. Glass transition temperatures of the blend shifted inward in the presence of the graft copolymer. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1248–1253, 2005     

含聚氧乙烯链段的两亲性接枝共聚物的合成及应用

介绍了含聚氧乙烯链段的两亲性接枝共聚物的制备方法与应用近况。     

Synthesis, characterization and micelle formation of amphiphilic graft copolymers

The macromonomer method is a useful tool for the preparation of various graft copolymers with well-defined structure and composition. Macromonomers were prepared by anionic polymerization of styrene followed by a direct coupling reaction of polystyryllithium with an excess of vinylbenzyl chloride. The control of the terminal functional groups is particularly important to ensure the reactivity of macromonomers in the radical copolymerization; the degree of functionality was determined by both n.m.r. and u.v.-vis. spectroscopy to be from 85–99%. Graft copolymers were synthesized by radical copolymerization of (vinylbenzyl) polystyrene macromonomer with 2-hydroxyethyl methacrylate (HEMA), or with acrylic acid. The organization ability of the copolymers to form micelles was investigated by ¹H n.m.r. spectroscopy, and verified by their ability to stabilize emulsions. These copolymers were found to be effective surfactants for emulsion polymerization of polystyrene latexes. © 1997 Elsevier Science Ltd.     

Synthesis and properties of amphiphilic thermo-sensitive block copolymers

Octadecyl acrylate (ODA) as hydrophobic monomer and N-isopropylacryamide (NIPAAm) as hydrophilic monomer were chosen to synthetize the thermo-sensitive block copolymers PODA_x-PNIPAAm_y-PODA_x (BAB-type) via reversible-addition-fragmentation chain transfer (RAFT) polymerization, the block copolymers could self-assemble to flower-like micelles in aqueous solution with hydrophobic PODA as the inner core and stabilized by hydrophilic PNIPAAm as the outer shell. The characterizations of the micelles such as surfactivity, thermo-sensitivity, micelle hydrodynamic radius (R _h ) and polydispersity index (PdI) were demonstrated by surface tension technique, UV-Vis, and dynamic light scattering (DLS) measurements, respectively. The longer the hydrophilic chain was, the higher the critical micellization concentration (CMC) would be, and the higher content of the PODA was, the lower the lower critical solution temperature (LCST) would be. The average R _h remained at about 100 nm below LCST, but decreased sharply to about 42 nm and kept constant when reaching and above LCST, which meant the non-aggregation of BAB type block copolymers. The micelle was homogeneous with the small PdI within the range of research. B_0.5mA_24mB_0.5m had the largest capacity to encapsulate lipophilic Sudan Red IV model drugs and the drug loading efficiency was 9.76%.     

Synthesis and surface properties of amphiphilic fluorine-containing diblock copolymers

Amphiphilic diblock copolymers (DCs) of 2,3,4,5,6-pentafluorostyrene (PFS) and 2-hydroxyethyl methacrylate (HEMA) of different composition and molecular weights were prepared by two-step reversible addition–fragmentation chain transfer (RAFT) polymerization and first used for preparation of superhydrophobic coatings for cotton/polyester fabrics. The transition from hydrophobic to superhydrophobic coatings is controlled by the ratio between poly(2,3,4,5,6-pentafluorostyrene) (PPFS) block and poly(2-hydroxyethyl methacrylate) (PHEMA) block lengths (P_n^PFS/P_n^HEMA). The increase in P_n^PFS/P_n^HEMA is accompanied by a significant increase in water (θ^Н₂^О) and diiodomethane (θ^CH₂^I₂) contact angles, which reach the plateau at P_n^PFS/P_n^HEMA = 3.5 and remains almost constant up to P_n^PFS/P_n^HEMA = 6.2. Surface modification of the cotton/polyester fabric with the DC having P_n^PFS/P_n^HEMA = 6.2 produced superhydrophobic surface with θ^Н₂^О = 158 ± 4° and contact angle hysteresis CAH = 5 ± 2°, and θ^CH₂^I₂ = 107 ± 3°.     

Synthesis,characterization and properties of amphiphilic butadiene-oxyethylene multiblock copolymers

Butadiene-oxyethylene multiblock copolymers were synthesized via coupling reaction of telechelic α,ω-dihydroxypolybutadiene (PB) and poly(ethylene glycol) with tolylene-2,4-diisocyanate. The poly(oxyethylene) (PEO) content of the purified copolymer was determined by elemental analysis and the structural parameters were calculated from number-average molecular weights of the purified copolymer, determined by membrane osmometry, and those of the prepolymers, determined by vapor pressure osmometry. The total number of blocks varied from 60 to 100. Transmission electron microscopy showed the existence of multiphases in the copolymer. Wide angle X-ray diffraction indicated that the crystallinity increased from 0 to 50% with increasing weight ratio of PEO/PB. These multiblock copolymers exhibit excellent emulsifying properties, as compared to the multiblock copolymers or graft copolymer of oxyethylene and styrene. Only 0.1 g of polymer was needed to make 100 mL of a water/toluene (9:1, w/w) mixture form an emulsion completely. When the weight ratio of water/toluene was changed from 9:1 to 7:3 or the molecular weight of PEG from 6000 to 2000, the oil-in-water type emulsion was changed to water-in-oil type. The copolymers also showed a good phase transfer catalytic effect when applied to the Williamson reaction. Conversion of potassium phenolate into butyl phenolate reached over 95% when the multiblock copolymer containing 3 mmol of PEO was used for 1 g potassium phenolate, whereas no reaction occurred without using the multiblock copolymer at 90°C for 4 h.     

Synthesis and characterization of novel comb-type amphiphilic graft copolymers containing polypropylene and polyethylene glycol

Amphiphilic comb-type graft copolymers containing polypropylene (PP) and polyethylene glycol (PEG) have been prepared. Polypropylene-g-polyethylene glycol comb-type thermoplastic amphiphilic copolymers were synthesized by the reaction between chlorinated polypropylene and polyethylene glycol in the presence of a base via a “grafting to” technique. A series of graft copolymers containing PEGs with molecular weights of 600 and 2,000 Da in the range of 4–34 mol% PEG were obtained. The amphiphilic graft copolymers with PEG segments in range between 20 and 30 mol% PEG displayed good film properties with elongation at break 275–440%. The hydrophilicity of the amphiphilic copolymers increases with the increasing PEG content in the copolymer while the mechanical properties decrease. Therefore, PP-g-PEG2000 with PEG contents in the range of 20–30 mol% PEG should be useful for medical and industrial applications where good film properties are needed.     

Synthesis and properties of three kinds of phenylenevinylene copolymers with dialkoxyphenylene units

Two random copolymers, poly(p-phenylenevinylene-co-2,5-didodecyloxy-p-phenylenevinylene) and poly(2,5-dimethoxy-p-phenylenevinylene-co-2,5-didodecyloxy-p-phenylenevinylene), were synthesized via the chlorine precursor route followed by thermal elimination. One alternating copolymer, poly(p-phenylenevinylene-alt-2,5-didodecyloxy-p-phenylenevinylene), was prepared via the Heck coupling reaction. The effects of molar ratio of monomers on yield and composition of the precursor copolymers were studied. The two precursor copolymers and the alternating copolymer were characterized by gel permeation chromatography, differential scanning calorimetry, elemental analysis, and infrared spectroscopy. The UV-visible absorption spectra and photoluminescence spectra, as well as solubility and conductivity of these copolymers, were compared. © 1998 John Wiley & Sons, Inc. J Appl Polm Sci 68: 937–946, 1998     

Synthesis and properties of unsaturated polyoxyethylene and its graft copolymers with styrene

The unsaturated polyoxyethylene (PEO) was synthesized by copolymerization of ethylene oxide with allyl glycidyl ether in toluene using bimetallic-oxo-alkoxide as a catalyst. The effects of polymerization conditions on conversion and intrinsic viscosity of the copolymer were studied. The unsaturated copolymer was characterized with infrared spectra, ¹H NMR, and wide-angle X-ray diffraction. The relationship between crystallinity of the copolymers and conductivity of their LiClO₄ complexes were investigated. The copolymer with ∼ 65 wt % PEO content exhibits a room temperature conductivity of 1 × 10⁻⁴ S cm⁻¹ at a molar ratio of EO/Li = 20. The unsaturated PEO was graft-copolymerized with styrene using 2,2′-azobis(isobutyronitrile) as initiator in toluene, with grafting efficiency ∼ 50%. The purified graft copolymer was characterized with infrared spectra, ¹H NMR, and wide-angle X-ray diffraction, and was shown to have good emulsifying properties and a phase-transfer catalytic property. LiClO₄ complex of the graft copolymer with 70 wt % PEO content exhibits a room temperature conductivity approaching 1 × 10⁻⁴ S cm⁻¹ at molar ratio of EO/Li = 20/1. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2417–2425, 1998     

Synthesis of well-defined graft copolymer with oligodimethylsiloxane and polyvinylalcohol branches

Summary Polyvinylalcohol macromer of well controlled molecular weight and molecular weight distribution, whose hydroxyl groups being protected as silyl ethers, was synthesized by Lewis acid catalyzed sequential silyl aldol condensation. Copolymerization of p-oligodimethylsiloxanylstyrene with the macromer, followed by the removal of the hydroxyl protective groups, gave the well-defined title graft copolymer.     

Synthesis and characterization of amphiphilic graft copolymers with poly(ethylene glycol) and cholesterol side chains

Amphiphilic graft copolymers comprising monomeric units of methoxy poly(ethylene glycol) (mPEG)-acrylate, 2-hydroxyethyl methacrylate (HEMA)–cholesterol conjugates and HEMA were synthesized and their properties characterized. The value of the critical micelle concentration (CMC) for these copolymers is linearly proportional to the ratio of the number of mPEG–acrylates to that of the HEMA–cholesterol conjugates per macromolecule (N_PEG/N_c), which is the most important parameter which influences the formation of polymeric micelles. The latter show excellent colloidal stability and their sizes decrease with increasing CMC. Based on the quenching of pyrene fluorescence, the relatively high levels of the loading capacity of pyrene are attributed to the elevated hydrophobicity of the micelle core. The loading capacity of pyrene decreases with increasing CMC. The weight-average partition coefficient for pyrene in polymeric micelles increases with increasing polymer concentration because more micelles are available for accommodating pyrene. Copyright © 2004 Society of Chemical Industry     

Synthesis,assembled structure,and chiroptical properties of amino acid-based amphiphilic block copolymers containing carbazole moiety

Novel amphiphilic block copolymers composed of amino acid-based hydrophilic segment and carbazole-containing hydrophobic segment were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. N-Ethyl-3-vinylcarbazole (E3VC) was employed as a carbazole-containing monomer, which can be regarded as a styrene derivative. N-Acryloyl-l-proline methyl ester (A-Pro-OMe) was selected as an amino acid-containing monomer, which is a disubstituted acrylamide with proline moiety in the side chain. Chain extension from poly(A-Pro-OMe) to E3VC could be well controlled under suitable conditions and provided block copolymers with as-designed chain structures and low polydispersities. The block copolymers were also synthesized by RAFT polymerization of A-Pro-OMe using poly(E3VC) as a macro-chain transfer agent (macro-CTA). In both cases, the dithiobenzoate- and dithiocarbamate-terminated CTAs were compared, in terms of the polymerization rate, polydispersity of the product, controlled character, and block efficiency. We investigated the relationship between the ordered structures, optoelectronic and chiroptical properties of the resulting block copolymers, which were evaluated by dynamic light scattering (DLS), UV–vis, fluorescent, and CD measurements.     

Semifluorinated ABA triblock copolymers: Synthesis,characterization, and amphiphilic properties

In this study a series of novel semifluorinated ABA triblock copolymers with different fluorinated segment lengths and different fluorocarbon side‐chain structures were synthesized via atom transfer radical polymerization (ATRP) and macroinitiator techniques. The macroinitiator, telechelic bromine terminated polystyrene, was obtained from bulk ATRP of styrene with α,α′‐dibromo‐p‐xylene as the initiator and cuprous bromide/α,α′‐bispyridine complex as the catalyst. The polymerization reactions of 2‐[(perfluorononenyl)oxy] ethyl methacrylate and ethylene glycol monomethacrylate monoperfluorooctanoate were initiated by the macroinitiator in the presence of additional catalyst. The characterization of the block copolymers was performed by gel permeation chromatography, ¹H‐NMR spectroscopy, and differential scanning calorimetry. The surface activities of the block copolymers in toluene were investigated with the Wilhelmy plate method. The solid surface energy of the block copolymers was determined by measurement of the contact angles. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2625–2633, 2002     

Synthesis of amphiphilic copolymers having capability as emulsifiers and their surface chemical properties

Some comblike terpolymers composed of methyl methacrylate (MMA), methoxypolyethyleneglycol methacrylate (MPEGMA) as a hydrophilic component, and methoxypolypropyleneglycol methacrylate (MPPGMA) as a hydrophobic component were synthesized by both living radical photopolymerization and ordinary radical polymerization. Since these terpolymers showed a high surface activity, it was suggested that they could be utilized as good polymeric emulsifiers. The polymeric emulsions containing these emulsifiers also showed comparatively good emulsion and mechanical properties as an adhesive. From these facts, it was found that these terpolymers had almost the same emulsification capability as commercially available low molecular weight emulsifiers. Conversely, a difference in surface tension behavior of these terpolymers could be observed. We think that it was due to the chain arrangements (random or block sequence) of the terpolymer. Amphiphilic copolymer Emulsion polymerization Polymeric emulsifier Micelle formation     

Synthesis and properties of amphiphilic copolymers of butyl acrylate and methyl methacrylate with uniform polyoxyethylene grafts

Amphiphilic copolymers of butyl acrylate (BA) and methyl methacrylate (MMA) with uniform polyoxyethylene (PEO) grafts were synthesized by the copolymerization of BA and MMA with a methacrylate‐terminated PEO macromer in benzene with azobisisobutyronitrile as an initiator. The effects of various copolymerization conditions on the grafting efficiency and molecular weight of the copolymers, as well as the effect of the copolymerization time on the conversions of the macromer and the monomers, were reported. The copolymers, with uniform PEO grafts, were purified by successive extractions with water and ether/acetone (3/7) to remove unreacted macromer and ungrafted copolymers of MMA and BA, respectively. The purified graft copolymers were characterized with IR, ¹H‐NMR, membrane osmometry, gel permeation chromatography, and differential scanning calorimetry. The highest grafting efficiency was about 90%, and molecular weight of the copolymers varied around 10⁵. The average grafting number of the copolymer was about 10. A study of the crystalline properties, emulsifying properties, phase‐transfer catalytic ability, and mechanical properties of the graft copolymers showed that the emulsifying volume decreased with the increasing molecular weight of the PEO grafts but increased with the PEO content. The conversion of potassium phenolate in the Williamson solid–liquid reaction obviously increased with an increasing PEO content of the graft copolymers. The crystallinity of the graft copolymers increased with the PEO content of the graft copolymers or the molecular weight of the macromer used. The copolymers, prepared under certain conditions, behaved as thermoplastic elastomers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2982–2988, 2003     

Synthesis, characterization, and antibacterial activity of metal nanoparticles embedded into amphiphilic comb-type graft copolymers

The synthesis, spectroscopic characterization, and antimicrobial efficiency of gold and silver nanoparticles embedded in novel amphiphilic comb-type graft copolymers having good film-forming properties have been described. Amphiphilic comb-type graft copolymers were synthesized by the reaction of chlorinated polypropylene (PP) (M _w = 140,000 Da) with polyethylene glycol (PEG) (M _n  = 2,000 Da) at different molar ratios. Metal nanoparticles embedded graft copolymers were prepared by reducing solutions of the salts of silver or gold and the copolymer in tetrahydrofuran. The optical properties of the metal nanoparticle embedded copolymers were determined by using UV–visible spectroscopy. Surface plasmon resonance (SPR) of the gold and silver nanoparticle embedded copolymers in toluene was observed at a maximum wavelength (λ_max) of 428 and 551 nm in the UV–VIS absorption spectra, respectively. The average particle diameters of the gold and silver nanoparticles were found to be 50 nm from the high resolution scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Amphiphilic polymer films containing silver and gold nanoparticles were found to be highly antimicrobial by virtue of their antiseptic properties to Escherichia coli and Staphylococcus aureus.     

Solubilization properties of N-substituted amphiphilic acrylamide copolymers

Amphiphilic copolymers of sodium 2-acrylamido-2-methylpropanesulfonate (AMPS) and dodecylmethacrylamide (DodMAAm) were synthesized. The ratio of the reduced viscosities of these copolymers in water and in 0.2 mol/L NaCl solution shows that these copolymers containing from 50 to 66 mol % of DodMAAm have a relatively small and constant hydrodynamic size. Viscometric and static light scattering measurements indicated that the copolymers shrinked and intermolecularly associated, forming interchain aggregates in water through hydrophobic interactions. These copolymers solubilize dl-α-tocopherol acetate, giving a transparent solution; but the solution became turbid in a month due to increasing intermolecular association. To suppress this excess intermolecular association, polymers with four different crosslinking ratios were synthesized. The polymer of a crosslinking ratio of 0.5 mol % showed a strong solubilization property, resulting in transparent solution with an improved stability. The fluorescence spectra of pyrene in the polymer solution proved that these copolymers could form strong hydrophobic domains, which solubilize a hydrophobic compound, in less than 30 w/w % ethanol solution. These copolymers could have an excellent function of sustained release of perfume as a novel function. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2447–2453, 1999     

Synthesis of amphiphilic triarm star block copolymers

We describe the synthesis and the characterization of amphiphilic triarm star block copolymers based on polystyrene, poly(methyl methacrylate), poly(ε caprolactone), poly(l lactide) and poly(ethylene oxide) blocks. This synthesis has been achieved by a new route consisting in 2 successive initiation steps on a core molecule (a 1,1-diphenyl-ethylene derivative bearing a protected hydroxy function) located at the end of a first block. Some results on adsorption onto TiO₂ and micellization studies are given. Preliminary results on solid state indicate an increase of the miscibility of the different incompatible blocks. Received: 3 November 1997/Revised version: 1 December 1997/Accepted: 2 December 1997     

Synthesis and properties of well-defined poly (dimethylsiloxane)-b-poly(2-hydroxyethyl methacrylate) copolymers

Block copolymers containing dimethyl siloxane and 2-hydroxyethyl methacrylate sequences were synthesized by group transfer polymerization (GTP) of 2-trimethylsilyloxyethyl methacrylate (TMS-HEMA) using silyl ketene acetal terminated poly(dimethylsiloxane) (PDMS) as macroinitiator, followed by hydrolysis of TMS-HEMA to HEMA. The block copolymers were obtained with controlled molecular weight and narrow molecular weight distribution. Trimethylsilyl groups in the P(TMS-HEMA) block could be selectively hydrolyzed without cleaving Si-O bond in PDMS block. The block copolymers formed micelles in methanol, the effective diameters (R_h) of which were in the range of 78 – 110 nm with narrow distribution by dynamic light scattering (DLS). The TEM image showed micelles with a spherical shape. Received: 10 May 2001/Revised version: 23 August 2001/Accepted: 24 August 2001     

Synthesis,properties and degradation of polyisobutylene–polyester graft copolymers

The development of copolymers is a promising approach for combining the favorable properties of two polymers and obtaining new properties of the combination. In this work, graft copolymers of polyisobutylene (PIB ) and polycaprolactone or poly(d ,l ‐lactide) were synthesized and studied. Amine‐terminated polyesters were synthesized and were grafted onto an activated PIB backbone synthesized from butyl rubber, a copolymer of isobutylene and 2 mol% isoprene. The polyester content was tuned from 15 to 44 wt% by varying the molar mass of the polyester blocks and the number of molar equivalents used in the grafting reaction. The graft copolymers with higher polyester content underwent nanoscale phase separation, as demonstrated by differential scanning calorimetry and atomic force microscopy imaging. This was found to provide enhanced mechanical properties such as increased tensile strength and Young's modulus relative to the starting rubber or physical blends. Despite the significant polyester content of the graft copolymers and the susceptibility of the polyesters to degradation, the graft copolymers underwent negligible mass loss in 5 mol L^?1 NaOH over a period of eight weeks. These results suggest that polyesters can be incorporated into PIB to tune and enhance its properties, while maintaining high chemical stability. © 2016 Society of Chemical Industry