Synthesis and flocculation performance of graft and random copolymer microgels of acrylamide and diallyldimethylammonium chloride

Graft (from linear homopolymers) and random (from a linear random copolymer) copolymer microgels of diallyldimethylammonium chloride (DADMAC) and acrylamide were synthesized via a free-radical mechanism using a γ-radiation technique. These copolymer microgels were evaluated as flocculants on a model dilute TiO₂ colloid suspension using a turbidimeter and a disc centrifuge photosedimentometer, and their performances were compared with the linear homopolymers and their blends. It was found that microgels produced after an appropriate irradiation time showed improved flocculation behavior over their nonirradiated linear counterparts. The graft microgels performed better than the corresponding random microgels. For a γ-radiation dosage of 100 krad/h, the graft microgels obtained by irradiating a 30% DADMAC (by weight) homopolymer blend for 3 h showed the maximum reduction in the relative turbidity of the TiO₂ suspension as well as the largest fraction of larger particles flocculated. Received: 18 May 1999 Accepted in revised form: 1 June 1999     

Synthesis and characterizations of a novel zwitterionic hybrid copolymer containing both sulfonic and carboxylic groups via sulfonation and zwitterionic process

A novel zwitterionic hybrid copolymer containing both sulfonic and carboxylic groups was synthesized via sulfonation, zwitterionic process and sol-gel reaction. The properties of the step products were characterized by FT-IR spectra, thermal analyses, MALDI measurements and SEM morphologies. FT-IR spectra confirmed the related reactions. TGA and DrTGA analyses showed that their thermal stability enhanced with an increase in the zwitterionic extent. DSC curves revealed that both the glass transition temperature and the melting temperature elevated with the rising content of ion pairs. MALDI measurements suggested that the molecular structure of the zwitterionic hybrid PEG-[Si(OEt)₃]₂SO₃HCOOH was more stable than that of neutral hybrid PEG-[Si(OEt)₃]₂ or that of negatively charged hybrid PEG-[Si(OEt)₃]₂SO₃H. SEM image of the sulfonated polymer film indicated that the pore size was within 2.4-6.1 μm; whereas SEM of the zwitterionized copolymer film displayed that its pore size was less than 1 μm. This shrinkage in pore size can be ascribed to the introduction of carboxylic groups into the copolymer chains. Compared with that observed in the unionized polymer film, the large difference in the morphology of the ionized copolymer films demonstrated that ionization could alter these copolymer’s characteristics. Due to its excellent pore-creating performance, this zwitterionic hybrid copolymer expects to be employed to prepare nanofiltration and ultrafiltration membranes.     

Use of block copolymer surfactants in the inverse-suspension polymerization of acrylamide

A comprehensive experimental investigation of the inverse microsuspension polymerization of acrylamide using an oil-soluble initiator and a block copolymeric surfactant whose hydrophobic miety is poly(12-hydroxystearic acid) and whose hydrophilic moeity is polyethylene oxide was carried out. It was found that the initial polymerization rate was first order with respect to molar monomer concentration, first order with respect to molar initiator concentration and zeroth order with respect to molar emulsifier concentration. Based on these experimental findings, a mechanism was proposed which includes initiation, propagation transfer to monomer and termination. It also includes transfer to impurities which are believed to be found in the surfactant. The kinetic model developed from the proposed mechanism is found to be in good agreement with the experimental conversion and weight-average molecular weight data. Comparing with sorbitan esters of fatty acids, the copolymeric surfactant provides higher polymerization rate and very high and linear molecular weight comparable to those obtained by solution polymerization.     

Separation properties of saccharides on a hydrophilic stationary phase having hydration layer formed zwitterionic copolymer

A novel water-holding adsorbent bonded with a zwitterionic polymer, diallylamine–maleic acid copolymer, was developed. With this adsorbent, hydrophilic solutes are partitioned by a hydration layer that forms on the zwitterions, as a main separating force. When the adsorbent was used to separate saccharides by normal-phase partition chromatography, the saccharides eluted in the order, mono-, di- and trisaccharide. The elution profile for mono- and di-saccharides was similar but not identical to that on anion exchange columns. This indicated that the adsorbent exhibited a complex retention behavior by the existence of both anion and cation exchange moieties in the functional polymer. Selecting Na⁺ as a counter-ion of the maleate moiety enhanced the retention of saccharide. When used in an high performance liquid chromatography (HPLC) system with gradient elution, the adsorbent enabled the simultaneous analysis of mono-, di- and oligosaccharides.     

Adsorption of polystyrene-poly(4-vinylpyridine) diblock copolymer on the assembled latex film

The Layer-by-Layer (LbL) technique was effectively used to embed anionic polystyrene (PS) latex particles into the assembled film deposited on a glass substrate. The high surface coverage of particles on poly(ethyleneimine) (PEI)-coated glass, determined from scanning electron microscopy (SEM) (80%), was attained within 1 h when using the latex containing sodium chloride (5 × 10⁻⁵ mol/l) at pH 6. After immersing the particles coated substrate in the polystyrene-poly(4-vinylpyridine) diblock copolymer (PS-PVPy) dissolved in tetrahydrofuran, the contact angle value indicated that the PS-PVPy could be adsorbed on the film to provide PS block at the outermost layer. The selective solvent, block length of PVPy, latex concentration, immersion time and ionic strength of aqueous solution of poly(allylamine hydrochloride) (PAH) previously adsorbed on the substrate showed influence on the adsorption of the block copolymer and, hence, the contact angle of the film.     

Synthesis, characterization and reactivity of a zwitterionic amine bridged bis(phenolate) lanthanide complex

A zwitterionic amine bridged bis(phenolate) ytterbium(III) complex was synthesized, and its reactivity with a zinc cluster was explored. The reaction of (C₅H₅)₃Yb(THF) with the amine bridged bis(phenol) HONNOH [ONNO = Me₂NCH₂CH₂N{CH₂-(2-O-C₆H₂-Bu^t₂-3,5)}₂] in a 1:2 M ratio in toluene at 80 °C produced the zwitterionic ytterbium complex [ONNO]Yb[ONNO(μ₄-H)] (1) in a high isolated yield. The reaction of ZnEt₂ with 1 equiv of PhCH₂OH gave a zinc cluster Zn₇Et₆(OCH₂Ph)₈ (2) in a good isolated yield. Complex 1 reacted with complex 2 in a 7:1 M ratio at room temperature to afford the unexpected ligand redistributed product [ONNO]Zn(THF) (3). These complexes were well characterized by elemental analyses, IR spectra and NMR spectroscopy in the case of complexes 2 and 3. The definitive molecular structures of complexes 2 and 3 were determined by single-crystal X-ray analyses.     

Synthesis and characterization of cationic and zwitterionic allyl zirconium complexes derived from trimethylenemethane (TMM) cyclopentadienylzirconium acetamidinates

Protonation of the trimethylenemethane derivatives, Cp*Zr(σ²,π-C₄H₆)[N(R¹)C(Me)N(R²)] (1a: R¹=R²=i-Pr and 1b: R¹=Et, R²=t-Bu) (Cp*=η⁵-C₅Me₅), by [PhNMe₂H][B(C₆F₅)₄] in chlorobenzene at −10 °C provides the cationic methallyl complexes, Cp*Zr(η³-C₄H₇)[N(R¹)C(Me)N(R²)] (2a: R¹=R²=i-Pr and 2b: R¹=Et, R²=t-Bu), which are thermally robust in solution at elevated temperatures as determined by ¹H NMR spectroscopy. Addition of B(C₆F₅)₃ to 1a and 1b provides the zwitterionic allyl complexes, Cp*Zr{η³-CH₂C[CH₂B(C₆F₅)₃]CH₂}[N(R¹)C(Me)N(R²)] (3a: R¹=R²=i-Pr and 3b: R¹=Et, R²=t-Bu). The crystal structures of 2b and 3a have been determined. Neither the cationic complexes 2 or the zwitterionic complexes 3 are active initiators for the Ziegler-Natta polymerization of ethylene and α-olefins.     

Synthesis, modification and characterization of core-shell fluoroacrylate copolymer latexes

Core-shell fluoroacrylate copolymer latex, typically used for the protection of ancient stone monument, was synthesized in this paper by semi-continuous seed emulsion polymerization with butyl acrylate (BA) served as the core, methyl methacrylate (MMA), BA and dodecafluoroheptyl methacrylate (DFHMA, C₁₁H₈O₂F₁₂) served as the shell. At the same time, the above core-shell fluoroacrylate latex was modified by hydrolysis of tetraethyl orthosilicate (TEOS, Si(OC₂H₅)₄) in the presence of silane coupling agent dodecyltrimethoxysilane (DTMS, C₁₂H₂₅Si(OCH₃)₃). The chemical component of the final latex was analyzed by FT-IR. Morphology structure and the particle size of core-shell latex were determined by TEM. The effect of DFHMA and TEOS content on the latex and film properties was characterized by SEM-EDX, AFM, TEM, DSC and UV-vis. The analysis results indicated that the copolymer latex particle presented uniform sphere core-shell structure with 40-50 nm in diameter. About 30 wt% DFHMA gave favorable characteristics both in latex and in film properties. Compared with core-shell fluoroacrylate latex, the modified fluoroacrylate copolymer displayed, when TEOS was controlled in 2.2-3.8 wt%, sound performances in hydrophobic, mechanics, thermodynamics and resistance to ultraviolet.     

Synthesis,characterization, and properties of copolymer of acrylamide and complex pseudorotaxane monomer consisting of cucurbit[6]uril with butyl ammonium methacrylate

The novel copolymers of acrylamide (AM) with complex pseudorotaxane monomer (BAMACB) of butyl ammonium methacrylate (BAMA) and cucurbit[6]uril (CB[6]) were prepared via free‐radical polymerization in aqueous solution. The copolymers containing pseudorotaxane (PAM/BAMACB) were characterized by ¹H‐NMR, FTIR, elemental analysis, TGA, and DSC. The glass transition temperature (T_g) of the copolymer PAM/BAMACB are higher than that of the copolymer of acrylamide and butyl ammonium methacrylate (PAM/BAMA) because of the enhanced rigidity and the bulky steric hindrance of BAMACB side chain in PAM/BAMACB. The molecular weights of copolymer PAM/BAMACB were obtained via static light scattering. The hydrodynamic radii of coils or aggregates were investigated by dynamic light scattering. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5999–6008, 2008     

Synthesis and characterization of star-comb styrene/butadiene copolymer

<正>A novel star-comb styrene/butadiene copolymer(SC-SBC) was synthesized by anionic polymerization and grafting reaction with epoxidized star liquid polybutadiene(ESPB) as coupling agent.The overall shape of the star-comb macromolecules can be altered by changing the molecular weight and number of the side chain.The molecular parameters and mechanical properties of the SC-SBC resins were investigated.The notched izod impact strength of the SC-SBC resins are excellent and reach as high as to 239 J/m.     

Synthesis and characterization of acrylamide-N-isopropyl acrylamide copolymer grafts on silicone rubber substrates

Radiation grafting has been used to modify the surface composition of a polymeric biomaterial without changing its mechanical properties. The graft copolymer surface modifications may result in significant changes in protein and cell adhesion to the surface, and thus in the overall biological response to the foreign material. In this paper we present a study of the radiation grafting of an unusual monomer, N-isopropyl acrylamide, and its copolymers with acrylamide, onto silicone rubber. This graft system may be able to influence protein adsorption and cell interactions in a unique fashion due to the special hydrophilic/hydrophobic balance and the unusual hydration character of the grafted copolymer.     

蓖麻油与乳酸的共聚物合成与表征

用熔融聚合法合成了一种蓖麻油和乳酸的共聚物.以丁二酸酐作为共聚体系的引发剂和封端剂,制得端羧基共聚物P(LA-CO)-COOH.研究了反应条件对共聚物分子量的影响,通过核磁共振表征了共聚物的结构.DSC和TG研究表明,蓖麻油链段的引入破坏了聚乳酸的结晶性,提高了共聚物的热稳定性.     

Synthesis and characterization of graft copolymer (alginate-g-poly(N,N-dimethylacrylamide))

<正>The graft copolymerization of N,N-dimethylacrylamide onto alginate by free radical polymerization using potassium peroxymonosulphate-sarbose as a redox pair in an inert atmosphere was investigated.The reaction conditions for maximum grafting have been optimized by varying the reaction variables,including the concentration of N,N-dimethylacrylamide(7×10~(-2) mol/L to 23×10~(-2) mol/L),potassium peroxymonosulphate(2×10~(-3) mol/L to 18×10~(-3) mol/L),sarbose(0.4×10~(-3) mol/L to 3.4×10~(-3) mol/L),sulphuric acid(1×10~(-3) mol/L to 8×10~(-3) mol/L) and alginic acid(0.4 g/L to 1.8 g/L) along with time duration(60 min to 180 min) and temperature(25℃to 45℃).Water swelling capacity,metal ion sorption and flocculation studies of the synthesized graft copolymer have been performed.The graft copolymer has been characterized by FTIR spectroscopy and thermogravimetric analysis.     

Synthesis and characterization of a high-efficiency light-emitting alternating copolymer

A new high-efficiency light-emitting alternating copolymer of triphenylamine and pure PPV (TPA–PPV) has been designed and synthesized. The copolymer was highly soluble in common solvents. It could be spin cast onto various substrates to give highly transparent homogeneous thin films without heat treatment. The fluorescence quantum yield in benzene is almost up to 1.00. The maximum fluorescence wavelength for this alternating copolymer appeared around 470 nm. The fluorescence of TPA–PPV solution quenched by C₆₀ was examined, and the result indicated that a strong interaction exists between TPA–PPV and C₆₀ at the exited state. A primary single-layer LED based on ITO/TPA–PPV/Al has been fabricated, and the onset voltage is only 1.5 V and a bright green light was observed. The electroluminescence spectrum gives a peak at 510 nm when the operating voltage of 17 V was applied. The photoluminescence spectrum also appeared at the same wavelength as the electroluminescence, indicating that the same excited states are involved in the two processes. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2587–2594, 1999     

Synthesis and flocculation performance of graft copolymer of <Emphasis Type="Italic">N</Emphasis> -vinylformamide and poly(dimethylaminoethyl methacrylate) methyl chloride macromonomer

 A comb-structured polymeric flocculant was synthesized by the aqueous copolymerization of N-vinylformamide (NVF) with poly(dimethylaminoethyl methacrylate) quats (methyl chloride) macromonomer. The effects of temperature and macromonomer concentration on the copolymerization kinetics were determined experimentally. The copolymerization reactivity ratio was measured to be 3.82 and 6.39 for NVF and macromonomers with 50 and 100 repeating units when copolymerized with NVF. The copolymer samples were also subjected to a flocculation performance test and were found to be more effective than linear random cationic copolymers in terms of cationic content, flocculation rate, final turbidity levels, and floc strength. Received: 11 June 2001 Accepted: 9 August 2001     

Synthesis of zwitterionic salts via three component reactions of nitrogen-containing heterocycles, acetylenedicarboxylate and cyclic 1,3-dicarbonyl compounds

A practical synthetic procedure for the preparation of the charge-separated pyridinium-Meldrum acid zwitterionic salts was developed through a unique one-pot three component reaction of pyridine, acetylenedicarboxylate and Meldrum acid. Other nitrogen-containing heterocycles such as N-methylimidazole, 2-picoline, quinoline, isoquinoline and other cyclic 1,3-dicarbonyl compounds such as 1,3-cyclopentanedione, 1,3-cyclohexanedione, barbituric acid also took part in the reaction to give corresponding zwitterionic salts in moderate yields, respectively. In one case an unusual isoquinolinium 1,3-cyclopentanedionate was obtained. A feasible explanation is given for this novel one-pot tandem reaction and the formation of different kinds of products.     

Synthesis and characterization of linear ABC triblock copolymer of ethylene oxide,methyl methacrylate,and styrene

A well‐defined linear ABC triblock copolymer of ethylene oxide (EO), methyl methacrylate (MMA), and styrene (St) was prepared by sequential living anionic and photo‐induced charge transfer polymerization (CTP) using p‐aminophenol as parent compound. In the first step, the diblock copolymer of PEO‐b‐PMMA with a protected aniline end group at PEO end was prepared by initiating of phenoxo‐anion the polymerization of EO and MMA successively, then the diblock copolymer of PEO‐b‐PMMA via deprotection of aniline at PEO end constituted a binary initiation system with benzophenone (BP) by charge transfer complex mechanism to initiate the polymerization of St under UV‐irradiation. The GPC and NMR measurements support that in copolymerization, either in the first or second step, neither homopolymer nor side reactions, such as chain transfer or chain termination, was found. The effect of the concentration of PEO_a‐b‐PMMA and St, and the polarity of solvent on the polymerization rate (R_p) of CTP is discussed. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 825–833, 1999     

Synthesis and characterization of polystyrene-b-polyisoprene-b-poly(methylmethacrylate) triblock copolymer

Polystyrene-b-polyisoprene-b-poly(methylmethacrylate) (PS-b-PI-b-PMMA) triblock copolymer was synthesized by sequential anionic polymerization. The as-synthesized triblock copolymer contains side products of inadvertently terminated PS and PS-b-PI precursors. The side products can be effectively removed by semi-prep scale liquid chromatography using multiple injection method to obtain pure PS-b-PI-b-PMMA. It was found that the removed side product contains another polymer species, coupled PS-b-PI, which could not be recognized by size exclusion chromatography (SEC) analysis since the elution peak of the coupled product overlaps with that of PS-b-PI-b-PMMA. This study demonstrates that the size based separation of SEC is often not good enough to characterize complex polymers precisely and interaction chromatography can render unique advantage over SEC analysis.     

Synthesis and characterization of nano Ag end capped L-cysteine bridged diblock copolymer

The target of the present investigation is synthesis and characterization of an amphiphilic diblock copolymer with antibacterial property. Ring opening polymerization (ROP) of ε-caprolactone (CL) and tetrahydrofuran (THF) was carried out under inert atmosphere by using L-cysteine as a bridging agent in the presence of stannous octoate (SO) as a catalyst. The nano silver end capped diblock copolymer was synthesized by in situ method. Thus obtained nano silver end capped L-cysteine bridged diblock copolymer was characterized by various analytical methods like Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, circular dichroism (CD), fluorescence spectroscopy, gel permeation chromatography (GPC), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) and zeta potential. The antimicrobial property of the nano silver end capped diblock copolymer against e-coli was tested.