Comparison of selective flocculation of low grade goethitic iron ore fines using natural and synthetic polymers and a graft copolymer

This study aims to beneficiate low grade goethitic iron ore fines using a selective flocculation process. Selective flocculation studies were conducted using different polymers such as starch amylopectin(AP), poly acrylic acid(PAA), and a graft copolymer(AP-g-PAA). The obtained results were analyzed; they indicate the enhancement of the iron ore grade from 58.49% to 67.52% using AP-g-PAA with a recovery of 95.08%. In addition, 64.45% Fe with a recovery of 88.79% was obtained using AP. Similarly, using PAA, the grade increased to 63.46% Fe with a recovery of 82.10%. The findings are also supported by characterizing concentrates using X-ray diffraction(XRD) and electron probe microanalysis(EPMA) techniques.

SYNTHESIS AND CHARACTERIZATION OF AMPHIPHILIC GRAFT COPOLYMER CONTAINING MICROPHASE SEPARATED AND LONG POLY(ETHYLENE OXIDE) SIDE CHAIN STRUCTURES

Acryloyl terminated Poly (ethyleneoxide)macromonomers (PEO-A) with different PEO chain lengths have been prepared by deactivation of PEO alkoxide with acryloyl chloride. A new kind of amphiphilic polystyrene-g-poly (ethylene oxide)graft copolymer containing both microphase separated and PEO side chain structures has been synthesized from radical copolymerization of PEO-A macromonomer with styrene. After careful purification by a newly-developed method called "selective dissolution’, the well-defined structure of the purified copolymers was confirmed by IR, ~1H-NMR and GPC. Various experimental parameters controlling the copolymerization were studied in detail. The results indicated that the feed ratio of styrene to macromonomer(S/M) was the most important determining factor for the composition of the copolymers. A detailed "comb- model" was proposed to describe the molecular structure of the graft copolymers. Finally, this amphiphilic graft copolymers may readily form microphase separated structures as clearly indicated by transmission electron microscopy.

Synthesis and Characterization of Degraded Gelatin Grafted Poly(ε-caprolactone) Copolymers

Hydrophilic degraded gelatin was modified with hydrophobic poly(ε-caprolactone) (PCL) via a chemical grafting route.Firstly,PCL with one hydroxyl end group was prepared by the ring-opening polymerization of εcaprolactone (ε-CL) with tin (Ⅱ) 2-ethylhexanoate as catalyst and n-butyl alcohol as initiator.Secondly,the PCL reacted with isophorone diisocyanate (IPDI) to prepare PCL with isocyanate functional group (PCL-NCO).Hydroxylamine was used to degrade gelatin by the cleavage between asparagine and glycine residues of gelatin.PCL-NCO reacted with the hydroxyl/amino groups of degraded gelatin in a homogeneous system and yielded the PCL modified gelatin copolymers.The gelatin grafted PCL copolymers were measured by means of XRD,FTIR,DSC and 1 H NMR.The results confirmed the conjugation of PCL onto gelatin chains.The PCL modified gelatin can be used as biomaterials owing to their biocompatibility and biodegradation.

Surface Photografting of Novel Sulfobetaine Copolymers on Silica

A couple of novel sulfobetaine copolymer is developed via Michael-type addition reaction. The comonomers, diamines and maleimide react via Michael reaction through UV irradiation using AIBN as photoinitiator producing polyamine chain. Further, sulfobetaine copolymers were obtained on treatment of the polyamine with sulfopropylating agent, 1,3-propane sultone. These novel sulfobetaine polymers were grafted on silica surface to produce responsive biocompatible surface. This easy straightforward, catalyst free facile protocol for synthesis of polymer grafted surface is useful for developing biomedical devices. Additionally, both the copolymers show fluorescence characteristics.

SYNTHESIS AND CHARACTERIZATION OF GRAFT COPOLYMERS BASED ON POLY(p-PHENYLENE TEREPHTHALAMIDE) BACKBONE AND WELL-DEFINED POLYSTYRENE SIDE CHAINS

新奇 dualfunctional 单体， 2-(2 鈥 ? 2 鈥 ? 6 鈥 ? 6 鈥 ? tetramethyl-piperidinyl-1 鈥 ? oxy ) methylbenzene-1,4-dioyl 氯化物 hydrochloride，与二酸，氯化物为生活基聚合的调停为步生长聚合和一个 nitroxide 组组织被综合。它首先与 terephthaloyl 氯化物和 p-phenylenediamine 被异分子聚合在一feed 在包含 10 wt%钙氯化物在的 N-methyl-2-pyrrolidone 的 1:3:4 的臼齿的比率?产出的 10 掳C 一(p苯撑 terephthalamide ) poly 基于 macroinitiator ，它在 125 掳C 开始了苯乙烯的激进的聚合获得一系列 poly (p苯撑 terephthalamide ) -g-polystyrenes 。质子的组合分析原子磁性的回声光谱学， Fourier 变换红外线的光谱学，基本分析， thermogravimetry 和胶化浸透层析显示 macroinitiator 导致了苯乙烯的激进的聚合以一个控制得好的方法继续。随单体变换的增加增加的方面链的分子的重量，和分子的重量分发索引仍然保持比 1.5 低。接枝共聚物大批在 N-methyl-2-pyrrolidone 和沮丧的 crystallinity 显示出显著地改进的溶解度。关键词 Dualfunctional 单体 - 接枝共聚物 -调停 Nitroxide 的生活免费激进的聚合 - Polycondensation - 完全芳香的聚酰胺这个工作被中国(号码 20774001 ) 和国家科学资金的国家自然科学基金会财政上为著名年轻学者(号码 20325415 ) 支持。

STUDY ON DYNAMIC MECHANICAL BEHAVIOUR OF POLY BUTYLACRYLATE GRAFT VINYL CHLORIDE COPOLYMERS

Dynamic mechanical behaviours of PVC ho-mopolymer,poly butylacryiate(PBA)graft vinylchloridecopolymers and blend of PVC and ACR have been investigated.The results reveal that there is semicompatible nature in the twophases in these materials,that the compalibility of the two phas-es decrease with the increase of crosslinking density of PBAbackbone in graft copolyes.For different copolymer types,PBAgraft copolymers had better compatibility of the two phases com- pared with the graft copolymers with core/shell backbone poly-mer.

SYNTHESIS AND CHARACTERIZATION OF REACTIVE GRAFT COPOLYMER PDMS-g-(PEO-OH)

A new reactive graft copolymer, poly （dimethyl siloxane ）-graft-ω-hydroxyl-poly（ethylene oxide） （PDMS-g-（PEO--OH））, was synthesized by the hydrosilylation reactionof α, ω-bifunctional PEO macromonomer （CH2=CH--CH2--PEO--OH） with poly（hydromethylsiloxane） （PHMS）. The obtained copolymer, exhibited the expected comb-like structure as indicated by the result of detailed characterization and the neededreactivity as demonstrated by the result of esterification between PDMS-g-（PEO--OH）and aminoacetic acid. This reactive graft copolymer is expected to be very useful in thepreparation of new bioactive polymer materials.

CHARACTERIZATION OF AMPHIPHILIC AND MICROPHASE SEPARATED GRAFT COPOLYMERS Ⅱ SURFACE CHARACTERIZATION AND IN VITRO BLOOD-COMPATIBILITY ASSESSMENT OF POLYSTYRENE-GRAFT-ω-STEARYLPOLY (ETHYLENE OXIDE)

This paper reported the research results concerning the surface characterization ofpolystyrene-graft-w-stearyl poly(ethylene oxide) (PS-g-SPEO) by means of XPS,contactangle measurement and TEM, and its in vitro blood compatibility assessment by measuringthe plasma recalcification time (RT) and partial thromboplastin time (PTT). The XPSresults demonstrated that the surface and bulk composition of the PS-g-SPEO graftcopolymers differ remarkably from each other,and that SPEO component was constantlyenriched at the copolymer/air interface. Contact angle studies indicated that the surfacewater wettability can be adjusted effectively by changing the composition of the copolymer.PS-g-SPEO graft copolymers can undergo microphase separation as clearly illustrated byTEM photographs. The relationship between the surface properties of PS-g-SPEO graftcopolymer and its blood compatibility was also discussed.

Synthesis, Purification and Characterization of Amphiphilic and Microphase Separated Graft Copolymer Polystyrene-g-Poly(ethylene oxide)

The present paper covers the poly (ethylene oxide) macromer with vinyl benzyl terminal group (PEO-VB) prepared by deactivation of the alkoxide function of mono-functional "living" PEO chains with vinyl benzyl chloride (VBC). The obtained macromers were subjected to careful purification and detailed characterization. A new kind of amphiphilic polystyrene-g-poly(ethylene oxide) (PS-g-PEO) with both mi-crophase separated and PEO side chains was synthesized from radical copolymerization of PEO-VB macromer with styrene monomer. An improved purification method, referred as "selective dissolvation", was established for the isolation of graft copolymers from the grafting products, and the purity and yield of the purified copolymers were satisfactory. The well-defined structure of the purified copolymers was confirmed by IR, 1H NMR and GPC. The bulk composition of the graft copolymers was determined by a well-established first derivative UV spectrometry. Various experimental parameters controlling the

SYNTHESIS OF AN AMPHIPHILIC PPESK-g-P(PEGMA)GRAFT COPOLYMER VIA ATRP AND ITS USE IN BLEND MODIFICATION OF PPESK MEMBRANES

Preparation of an amphiphilic graft copolymer having poly(phthalazinone ether sulfone ketone)(PPESK) as main chains was carried out by atom transfer radical polymerization(ATRP).The precursor,chloromethylated PPESK (CMPPESK),was prepared by using chioromethylether as chloromethylation agent.Then,poly(ethylene glycol) methyl ether methacrylate(PEGMA) was used as monomer to synthesize PPESK-g-P(PEGMA) by ATRP method under the catalysis of a cuprous chloride/2,2'-bipyridyl system.PPESK/PPESK-g-P(PEGMA) blen...

Design and comparative in-vitro and in-vivo evaluation of starch-acrylate graft copolymer based salbutamol sulphate sustained release tablets

The present work deals with the development of controlled release tablets of salbutamol sulphate(SS)using graft copolymers of methyl methacrylate(St-g-PMMA and Ast-g-PMMA)on starch and acetylated starch.Formulations were evaluated for physical characteristics like hardness,friability,drug release,drug content and weight variations,which fulfilled all the official requirements of tablet dosage form.The release rates from formulated matrix tablets were studied at SGF(pH 1.2)followed by SIF(pH 6.8).Drug release from the graft copolymer based tablets was found to be sustained upto the 14 h with>75%drug release.The in-vitro release study showed that the graft copolymer based matrix formulations(F3&F4)exhibited highest correlation value(r2)for higuchi kinetic model and Korsmeyer's model with n values between 0.61 and 0.67 proved that release mechanisms were governed by both diffusion and erosion mechanism.There was no significant difference in the pharmacokinetic parameters(tmax,Cmax,AUC,Ke,and t1/2)of the graft copolymers matrices and HPMC K100M matrix tablets,indicating their comparable sustained release effect.The potential of graft copolymers to sustain the drug release is well supported by in-vivo pharmacokinetic studies and their adequate physicochemical properties make them promising excipients for controlled drug delivery system.

Self-assembly of block copolymers grafted onto a flat substrate:Recent progress in theory and simulations

Block copolymers are a class of soft matter that self-assemble to form ordered morphologies on the scale of nanometers, making them ideal materials for various applications. These applications directly depend on the shape and size of the self-assembled morphologies, and hence, a high degree of control over the self-assembly is desired. Grafting block copolymer chains onto a substrate to form copolymer brushes is a versatile method to fabricate functional surfaces. Such surfaces demonstrate a response to their environment, i.e., they change their surface topography in response to different external conditions. Furthermore, such surfaces may possess nanoscale patterns, which are important for some applications; however, such patterns may not form with spun-cast films under the same condition. In this review, we summarize the recent progress of the self-assembly of block copolymers grafted onto a flat substrate. We mainly concentrate on the self-assembled morphologies of end-grafted AB diblock copolymers, junction point-grafted AB diblock copolymers(i.e.,Y-shaped brushes), and end-grafted ABA triblock copolymers. Special emphasis is placed on theoretical and simulation progress.

Surface Graft Copolymerization of Acrylic Acid onto Corona Treated Cotton Fabric

Acrylic acid was grafted onto the surface of cotton fabric after being short time treated by corona-discharge inair in the presence of initiator.The means of gas-phaseSO2 derivatization was used along with ESCA to deter-mine corona-discharge-induced-hydroperoxidegroups on the surface.The content of hydroperoxideshows a maxmium value at 15 sec.of corona-dischargetime.Effect of corona treatment time and various con-centration initlator on graft yield was studied.The addit-ion of initiator increases the graft yield.Acceleratedgraft with an increase in the concentration of Mohr’s saltshows that peroxide groups on the corona treated cottonfabric initiate graft copolymerization.

The Optimized Synthesis of Starch-g-Lactic Acid Copolymer with High Grafting Degree Catalyzed by Sulfuric Acid

The starch-g-lactic acid copolymer was synthesized with catalysis of sulfuric acid by onestep process, and the structure of starch-g-lactic acid copolymer was characterized by means of IR, 13C-NMR, HMBC, XRD, and SEM. The experimental results show that the maximum grafting degree of starch can reach 75% when the starch-g-lactic acid copolymer is activated at 80 ℃ for 2 h and reacted with lactic acid at 90 ℃ for 4 h in vacuum.

CHARACTERIZATION OF RADIATION GRAFT COPOLYMER OF INORGANIC COMPOUND ONTO ALKENE

ＣＨＡＲＡＣＴＥＲＩＺＡＴＩＯＮＯＦＲＡＤＩＡＴＩＯＮＧＲＡＦＴＣＯＰＯＬＹＭＥＲＯＦＩＮＯＲＧＡＮＩＣＣＯＭＰＯＵＮＤＯＮＴＯＡＬＫＥＮＥＺｈａｎｇＷａｎｘｉ；ＣｈｅＪｉｔａｉ；ＹａｎＭｅｉｌａｎ（ＣｈａｎｇｃｈｕｎｉｎｓｔｉｔｕｔｅｏｆＡｐｐｌｉ...

SYNTHESIS OF A COMB GRAFT COPOLYMER VIA RING OPENING METATHESIS POLYMERIZATION CATALYZED BY SUPPORTED RHUTHENIUM CARBENE COMPLEX

Chloromethyl-2-norbornene was synthesized via Diels-Alder reaction of cyclopentadiene and allyl chloride using a polymer supported boron trifluoride as the catalyst, and was then lithiated and used to initiate a living anionic polymerization of styrene to prepare a macromonome, 5-polystyryl-2-norbornene NBPS. Comb graft copolymer PNBgPS was synthesized via ring opening metathesis polymerization of the macromonomer under the catalysis of ruthenium carbene complex RuCl2(PPh3)2(=CCHtBu) and its polymer supported correspondent. Experimental results showed that the behavior of both the supported boron and supported ruthenium catalysts are superior to their unsupported counterparts. The possible promotion mechanism of the tailor-made supports is discussed.

Synthesis and characterization of star-comb styrene/butadiene copolymer

新奇星梳子苯乙烯 / 丁二烯共聚物(SC-SBC ) 被 anionic 聚合和 grafting 反应作为联合代理人与 epoxidized 星液体 polybutadiene (ESPB ) 综合。星梳子大分子的全面形状能被改变方面链的分子的重量和数字改变。分子的参数和 SC-SBC 树脂的机械性质被调查。SC-SBC 树脂的 notched izod 影响力量是优秀的并且至于 239 J/m 作为高度到达。

Synthesis and Characterization of Chitosan-g-poly- (D, L-lactic acid) Copolymer

Biodegradable chitosan-g-poly (D, L-lactic acid) copolymers were prepared via two methods. (1) The lactide was grafted onto hydroxyl groups of chitosan by using macromolecular initiator sodium of trimethylsilyl-chitosan, (2) poly (D,L-lactic acid)(PLA) with low molecular weight can be linked to the amino group by coupling activated PLA to trimethylsilyl-chitosan. Two graft copolymers had hydrophilic-hydrophobic character and can be applied as carriers for drug delivery.

MOLECULAR DESIGN SYNTHESIS AND PROPERTIES OF SIX KINDS OF MULTIPHASE (STYRENE-ETHYLENE OXIDE)COPOLYMERS

Multiphase copolymers of styrene (S) and ethylene oxide (EO) are amphiphilic, because of the hydrophobic and amorphous polystyrene (PS) segments and the hydrophilic and crystalline polyoxyethylene (PEO). They have many uses including polymeric surfactants, electrostatic charge reducers, compatibilizer in

淀粉接枝丙烯酰胺与聚丙烯酰胺对高岭土动态絮凝差异的研究

高岭土等黏土矿的存在是煤泥水沉降效果差的主要原因,目前尚未有关于难沉降煤泥水动态絮凝过程的研究。相较于聚丙烯酰胺(PAM)合成单体的毒性,淀粉接枝丙烯酰胺(SAM)合成的单体可降解性好。为此,以高岭土为研究对象,系统对比了SAM与PAM对高岭土动态絮凝过程的影响。首先,考察了不同SAM与PAM用量下的沉降速度和絮凝效果。随后,通过聚焦光束反射测量(FBRM)和颗粒录影显微镜(PVM)技术研究了高岭土悬浮液在SAM和PAM作用下的不同粒级颗粒数量变化。沉降实验和FBRM-PVM测试结果表明,PAM能够形成更多的+100μm大絮团,使得PAM具有更好的沉降效果;SAM形成的絮团更稳定,对细颗粒的絮凝效果更好。最后,通过FBRM获得的数据,基于Smoluchowski模型计算了PAM和SAM作用下高岭土的絮凝动力学参数,发现PAM作用下的絮凝指数明显高于SAM,同时-30μm和30~60μm颗粒数量的动态变化主导了絮凝动力学中絮团的形成过程。总体而言,PAM可以形成更多的、松散的大絮团,有利于高岭土的快速沉降,但对微细颗粒絮凝效果不佳。相较于PAM,SAM独特的多链立体网状结构,有利于微细颗粒絮凝和形成稳定的絮团,从而避免选煤厂洗水系统中细泥的循环积聚。