Characterization of cationic polyacrylamide‐grafted starch flocculant synthesized by one‐step reaction

Cationic polyacrylamide‐grafted starch (St‐g‐CPAM) flocculant was prepared by using corn starch and acrylamide (AM) as monomers, dimethyl diallyl ammonium chloride (DMDAAC) as cationic monomer through solution polymerization. The effects of initiator, reaction temperature, and monomer concentration on flocculation, the efficiency of grafting, and the yield of grafting were investigated. The results show that the optimal conditions of the polymerization are as follows: the concentration of ceric ammonium nitrate is 0.5%, the reaction temperature is 60°C, the concentration of total monomer is 20%, and the monomer ratio between AM and DMDAAC is 7 : 3. The flocculation capability was characterized by turbidity reduction. The thermal behavior, chemical structure, and microstructure of St‐g‐CPAM were also investigated by thermal gravimetric, IR, and SEM analyses. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis of a novel amphoteric chelating polymer flocculant and its performance in Cu2+ removal

A novel amphoteric chelating polymer flocculant (ACPF) was synthesized. The synthesis involved the copolymerization of dimethyldiallylammonium chloride and acrylamide to prepare poly(dimethyldiallylammonium chloride‐co‐acrylamide) [P(DMDAAC‐co‐AM)], Mannich reaction of P(DMDAAC‐co‐AM) with triethylenetetramine and formaldehyde to prepare P(DMDAAC‐co‐AM)‐graft‐TETA, and xanthogenation of P(DMDAAC‐co‐AM)‐graft‐TETA with CS₂ and NaOH. The removal performance of ACPF toward Cu²⁺ was investigated, and the ACPF structure was characterized. ACPF performance considerably improved at 121–187 mL/g intrinsic viscosity, 20.78–28.32 mol % cationic degree of P(DMDAAC‐co‐AM), and 22.11–28.44% sulphur content of ACPF. The Cu²⁺ removal rate was above 99% at a 1.98 : 1 molar ratio of ‐CSS^? to Cu²⁺. This rate was 5.86% higher than that using polyacrylamide‐graft‐triethylenetetramine‐dithiocarbamate (PAM‐graft‐TETA‐DTC). The zeta potential and sedimentation rate of flocs obtained from ACPF were higher and their volume was smaller than those from sodium triethylenetetramine‐multidithiocarbamate and PAM‐graft‐TETA‐DTC at the same sulphur dosage. This result indicates that the positive charges of ACPF polymeric chains effectively neutralize excess negative charges in flocs, which benefits the bridging of flocs with negative charges to promote their formation and growth. These positive charges can also cause the flocs to become larger and tighter, thereby improving flocculation and settling performance. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

高相对分子质量阳离子型聚丙烯酰胺合成工艺的研究

以丙烯酰胺(AM)和二甲基二烯丙基氯化铵(DMDAAC)为单体,采用溶液聚合法制备DMDAAC-AM共聚物。用正交实验法考察了引发剂用量、温度、单体配比、pH等因素对共聚物阳离子度、特性黏度,以及相对分子质量的影响。结果表明,温度为70℃,pH=8,引发剂量为4 mL,DMDAAC∶AM(质量比)=1∶1时,得到的阳离子型聚丙烯酰胺(CPAM)的相对分子质量最大。用所制得的CPAM对高岭土模拟悬浊水样进行的絮凝实验,发现相对分子量为1.73×106的CPAM的絮凝效果最好,浓度为0.05%的CPAM溶液仅用0.4 mL便可使浊度为22.4的皂土悬浮液的浊度去除率达到85.8%。     

Novel,rosin‐based,hydrophobically modified cationic polyacrylamide for kaolin suspension flocculation

A novel, hydrophobically modified cationic polyacrylamide (HMPAM) was synthesized via the copolymerization of acrylamide, diallyl dimethyl ammonium chloride (DMDAAC), and diallylmethyl dehydroabietic acid propyl ester ammonium bromide. Optimum conditions for preparing HMPAM were such that the amount of initiator was 0.075 wt % of the total monomer mass, the monomer concentration was 20 wt %, and the amount of DMDAAC was 18 mol % of the total monomer molar mass. HMPAM was characterized with an UV–visible spectrometer, ¹H‐NMR, Ubbelohde viscometer, rotational viscometer, and rotational rheometer. HMPAM solutions exhibited strong hydrophobic associations, and the critical association concentration of the HMPAM aqueous solution was about 0.7 wt %; the HMPAM solutions also showed salt thickening and shear resistance. The surface morphologies of the freeze‐dried HMPAM samples (1 wt %) were also observed via scanning electron microscopy. Compared with unmodified cationic polyacrylamide, Synthesis of HMPAM‐0.5 exhibited a stronger flocculation capacity, and the optimal transmittance of the supernatants was above 95%. HMPAM‐0.5 showed significant flocculation performances for 3–4 and 3–5 wt % kaolin suspensions at 40 and 50 mg/L, respectively. Moreover, the flocculation performance was enhanced with the addition of NaCl and CaCl₂. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46637.     

Synthesis,characterization, and flocculation properties of poly(acrylamide‐methacryloxyethyltrimethyl ammonium chloride‐methacryloxypropyltrimethoxy silane)

A novel hydrophobically modified and cationic flocculant poly(acrylamide‐methacryloxyethyltrimethyl ammonium chloride‐methacryloxypropyltrimethoxy silane) (P(AM‐DMC‐MAPMS)) was synthesized by inverse emulsion polymerization. The molecular structure of hydrophobically cationic polyacrylamide (HCPAM) was characterized by FTIR and ¹H‐NMR. The effects of DMC and MAPMS feed ratio on intrinsic viscosity and solubility were measured. The effects of hydrophobically cationic flocculants on reactive brilliant red X‐3B solution and kaolin suspension were studied. It was found that the introduction of MAPMS could increase the intrinsic viscosities of P(AM‐DMC‐MAPMS) and enhance the flocculation properties to anionic dye solution and kaolin suspension, but reduced their water‐solubility. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Homogeneous complex solution formed through interactions of poly(acrylamide‐co‐acrylic acid)/poly(acrylamide‐co‐dimethyldiallylammonium chloride) complex with M n+ hydration metal ions in aqueous media

A homogeneous complex solution, formed through inter‐polyelectrolyte complexation of poly(acrylamide‐co‐acrylic acid) (P(AM‐AA)) with poly(acrylamide‐co‐dimethyldiallylammonium chloride) (P(AM‐DMDAAC)) and interaction of the P(AM‐AA)/P(AM‐DMDAAC) complex with M ⁿ⁺ hydrated metal ion, was prepared and the structure and properties of the P(AM‐AA)/P(AM‐DMDAAC)/M ⁿ⁺ homogeneous complex solution were studied by UV spectrometry, dynamic light scattering and viscometry. The experimental results show that the homogeneous complex solution can be obtained by controlling the composition of the P(AM‐AA)/P(AM‐DMDAAC) complex and the M ⁿ⁺ metal ion content. Compared to the constituents, ie the P(AM‐AA) solution, the P(AM‐DMDAAC) solution and the P(AM‐AA)/P(AM‐DMDAAC) complex solution, the P(AM‐AA)/P(AM‐DMDAAC)/M ⁿ⁺ complex solution has a new peak at 270 nm in its UV spectrum, a larger hydrodynamic radius, and hence a higher solution viscosity, all of which indicate that there exist specific interactions between polymers and M ⁿ⁺ metal ions. These interactions lead to the formation of a network structure and hence an obvious increase not only in solution viscosity but also in resistance of the polymer solution to simple salts, to temperature changes and to shearing. © 2001 Society of Chemical Industry     

High‐temperature resistance water‐soluble copolymer derived from acrylamide,DMDAAC, and functionalized sulfonamide for potential application in enhance oil recovery

A water‐soluble poly(AM‐AA‐DMDAAC‐TCAP) was prepared using acrylamide (AM), acrylic acid (AA), diallyl dimethyl ammonium chloride (DMDAAC), and N‐allyl‐4‐methylbenzenesulfonamide (TCAP), and the synthesis conditions were investigated. The obtained copolymer was characterized by FTIR, ¹H‐NMR, SEM, TG, and XRD. The temperature resistance and thickening function of the copolymer are improved significantly compared with that of partially hydrolyzed polyacrylamide. It is found that the viscosity of copolymer could achieve up to 53.3% retention rate at 120°C compared to that at 30°C. About 16.6% for enhanced oil recovery is obtained by poly(AM‐AA‐DMDAAC‐TCAP) brine solution at 65°C. In addition, the results of XRD show that 3000 mg/L copolymer combined with 10 wt % KCl solution could reduce the d‐spacing of sodium montmorillonite from 18.94 to 14.86 Å exhibiting remarkable effect on inhibiting hydration of clays. All the results demonstrate that poly(AM‐AA‐DMDAAC‐TCAP) have excellent performance for potential application in enhance oil recovery. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40727.     

Modification of β‐cyclodextrin for rapidly decolorizing the dye‐containing wastewaters by flocculation

To strengthen the role of polymer bridging during the flocculation process and thus raise the speed of decolorizing the dye‐containing wastewaters, β‐cyclodextrin–acrylamide–[2‐(Acryloyloxy)ethyl] trimethyl ammonium chloride copolymer (poly[AM(β‐CD)‐AETAC]) with relatively high intrinsic viscosity (84.3 mL g^?1) and cationicity (24.5%) was prepared by solution polymerization. The successful preparation of copolymer was demonstrated by FT‐IR and ¹H‐NMR characterizations. Its excellent decolorization performances as a new flocculant were evaluated with the C.I. reactive orange 5 (RO 5) and C.I. reactive blue 19 (RB 19) solutions using a jar test method. Both the nature of anionic dyes and the pH of dye solutions influence the decolorization effectiveness. For both the RB 19 and RO 5 solutions (0.10 g L^?1), it can be rapidly decolorized in a wide range of pH (2–7) and flocculant concentration (0.12–0.26 g L^?1). For the given dye/flocculant solution system, both charge neutralization and polymer bridging contribute to the decolorization mechanism. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 39940.     

Dispersion—flocculation studies on a Goethite-clay system

Dispersion–flocculation studies on a Goethite–clay system using flocculants were carried out as a function of flocculant concentrations, pH of slurry, time of agitation and dispersant dosage. Also, the effects of pH and polymer concentrations on the adsorption behaviour of the system were investigated. Results show that well flocculated goethite was preferentially obtained from 4% goethite/kaolinite clay suspensions, with 50 ppm causticised starch in the slurry at pH values of 3–11·5 and with 50 ppm polyacrylamide at pH values of 3–8. Good flocs were also obtained on flocculation of the goethite suspension with 50 ppm polyacrylamide at pH values of 5–7, while the kaolinite suspension did not respond to the same dosage of causticised starch in the same pH range. Results further reveal that for the goethite/kaolinite suspension, the best results was obtained with 50 ppm polyacrylamide at pH values of 7–10. Based on the data generated in the study, it was concluded that causticised starch is a better flocculant than polyacrylamide for goethite suspensions although polyacrylamide is an excellent flocculant for kaolinite suspensions.     

AM/DMDAAC/AA型两性聚丙烯酰胺的制备及应用研究

以丙烯酰胺(AM)、二甲基二烯丙基氯化铵(DMDAAC)、丙烯酸(AA)为单体,用溶液共聚法制备两性聚丙烯酰胺(AMPAM),研究了反应条件对两性聚丙烯酰胺分子量及絮凝性能的影响。结果表明,采用K2S2O8-NaHSO3(质量比1∶1)氧化还原复合引发体系,引发剂用量为0.88%,单体用量为24.5%,聚合温度为55℃,溶液pH值为6,单体摩尔比为n(AM)∶n(DMDAAC)∶n(AA)=1∶0.3∶0.5,聚合时间为4 h,得到的产品综合性能最佳,且具有良好的絮凝脱色效果。     

疏水改性阳离子型丙烯酰胺共聚物的微结构与絮凝性能

用自由基胶束聚合法合成了丙烯酰胺（AM）/丁基苯乙烯（BS）/二甲基二烯丙基氯化铵（DMDAAC）疏水缔合型高分子絮凝剂PBAD。通过UV、FT-IR表征了共聚物的分子结构,AFM研究表明,由于丁苯基疏水基团强的分子间作用,0.005 g.dL-1 PBAD在水溶液中已形成了缔合体,并随着聚合物浓度的增加,缔合结构的尺寸和数量显著增加。在3%硅藻土溶液中,PBAD絮凝的最佳用量为0.005 g.dL-1,此时的透光率为96.5%,污水中的NaCl浓度能明显影响聚合物的架桥吸附作用,Ca2+和Al3+能增强聚合物的絮凝效果。     

Flocculation behavior of cationic pea starch prepared by the graft copolymerization of acrylamide for wastewater treatment

To improve the flocculation efficiency of coal mine wastewater treatment, we synthesized a cationic flocculant by grafting acrylamide (AM) onto pea starch, and we performed the characterization with elemental analysis, Fourier transform infrared spectrometry, scanning electron microscopy, thermogravimetric analysis, and NMR. The effects of the synthesis conditions were also investigated, and the optimal synthesis parameters of the cationic flocculant were obtained. The mass ratio between pea starch and AM was 0.5 with a reaction temperature of 65 °C. The dosages of ceric ammonium nitrate and 3‐chloro‐2‐hydroxypropyl‐trimethylammonium chloride were 0.02 and 0.11 mol/L, respectively. Application experiments for wastewater treatment were carried out consequently, and the optimal dosage of cationic pea starch was 40 mg/L within the pH range 6–8. Compared with other traditional flocculation products, the cationic pea starch showed the best flocculation behavior for coal mine wastewater. Therefore, the cationic pea‐starch‐grafted AM may be applicable as a novel flocculant in wastewater treatment and has already demonstrated outstanding features. It is bound to replace other traditional flocculants in the future. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43922.     

Influence of polymer morphology on the adsorption behaviors of molecularly imprinted polymer‐methacrylic acid functionalized β‐cyclodextrin

The influence of molecularly imprinted polymer‐methacrylic acid functionalized β‐cyclodextrin (MIP(MAA‐β‐CD)) morphology on the adsorption behavior studies towards benzylparaben (BzP) was explored. The effects of time, concentration, and temperature towards BzP uptake were extensively evaluated. The adsorption performance of MIP(MAA‐β‐CD) was compared with that on the molecularly imprinted polymer‐methacrylic acid (MIP(MAA)) synthesized without β‐CD. The MIP(MAA‐β‐CD) was synthesized to obtain a spherical and spongy‐porous texture with a broad pore size distribution. The MIP(MAA‐β‐CD) showed fast kinetic and the intra‐particle diffusion model demonstrated a three step (surface and pore) adsorption process. The Koble‐Corrigan isotherm was the most suitable model for data fitting, which indicated that MIP(MAA‐β‐CD) had homogeneous and heterogeneous surfaces. This finding clearly demonstrated that the large uptake and strong affinity of MIP(MAA‐β‐CD) did not only probably result from the monomer‐template interactions, but also due to the morphological MIP(MAA‐β‐CD) structure. In contrary to MIP(MAA‐β‐CD), MIP(MAA) synthesized with uniform morphology and narrow pore size distribution had lower adsorption capacities and its kinetic data fitted the pseudo‐second order diffusion model, indicating a two‐step (surface only) adsorption process. The MIP(MAA) adsorption process followed the Langmuir isotherm model referred to solely homogeneous uptake. The calculated thermodynamic parameters showed that the BzP uptake was exothermic, spontaneous, and physisorption process onto MIPs, which supported the results of kinetics and isotherm adsorption data. This study clearly revealed that the presence of β‐CD improved the morphology of synthesized MIP, and automatically enhanced the adsorption behavior of MIP. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42720.     

The synthesis of modified alginate flocculants and their properties for removing heavy metal ions of wastewater

A new flocculant was synthesized through the modification of sodium alginate with thiosemicarbazide. In the preparation, amino thiourea groups which had excellent adsorption properties for heavy metal ions were introduced to the flocculant. The structure of the flocculant was confirmed by elemental analysis, Fourier transform infrared, UV spectrophotometry, nuclear magnetic resonance, and thermal analysis. The flocculation behaviors of the flocculant for three heavy metal ions were investigated. The results showed that the removal rates of the flocculant for Pb²⁺, Cd²⁺, and Cu²⁺ reached up to 97.8%, 86.3%, and 80.0%, respectively, and the flocculation capacities were as high as 489, 215, and 160 mg/g, respectively. The excellent adsorption was ascribed to the double effects of electronic interaction and chelation between the flocculant and heavy metal ions. The flocculant had particular flocculation selectivity for Pb²⁺ in the mixed heavy metal ion solutions containing Cd²⁺or Cu²⁺, respectively. The flocculation process corresponded to Langmuir isotherm model, the flocculation kinetics agree with pseudo second order. The flocculant had potential applications for treatment of wastewater. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46577.     

反相乳液共聚合制备高分子絮凝剂工艺及产物性能

以丙烯酰胺（AM）和二烯丙基二甲基氯化铵（DMDAAC）为共聚单体,采用反相乳液聚合方法合成了高相对分子质量和高阳离子结构单元含量的共聚物絮凝剂（PDA）,比较了不同种类引发剂和分散剂等对聚合过程的影响,优化了聚合体系。考察了单体配比、引发剂浓度和乳化剂含量等因素对单体转化率和产物相对分子质量的影响。采用傅里叶红外光谱（FT-IR）、核磁共振氢谱（1H NMR）和紫外可见分光光度计等对所得高分子絮凝剂进行了结构和性能表征。红外光谱、核磁共振氢谱和黏度测试结果表明,丙烯酰胺和二烯丙基二甲基氯化铵进行了共聚合反应并得到了高分子产物,且产物中二烯丙基二甲基氯化铵组分含量远高于相应条件下水溶液聚合产物。当[DMDAAC]/[AM]=1∶4、引发剂浓度为30mmol/L、乳化剂含量为18%时,产物黏均相对分子质量可达2.2×105,阳离子单元含量达17%。     

A new cation‐modified Al‐polyacrylamide flocculant for solid–liquid separation in waste drilling fluid

A new cation‐modified Al‐polyacrylamide (CAPAM) flocculant was prepared by the in situ polymerization of acrylamide (AM) and (2‐methacryloyloxyethyl) trimethyl ammonium chloride (DMC) with Al(OH)₃ sol. The optimum preparation conditions were obtained by a one‐factor experimental design: as the amount of AlCl₃ was fixed at 0.025 mol, the polymerization time, polymerization temperature, n(AM) : n(AlCl₃), n(DMC) : n(AlCl₃), and n(K₂S₂O₈) : n(AM) were 4 h, 70°C, 8, 0.9, and 1.82 × 10^?3, respectively. The CAPAM was characterized by thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. The solid–liquid separation performance of the CAPAM was evaluated in terms of water content. The CAPAM showed better flocculation performance than cationic polyacrylamide and polyaluminum sulfate at a fixed concentration of 0.3% in waste drilling fluid and tended to perform well in alkaline solution. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41641.     

Synthesis of chitosan‐graft‐β‐cyclodextrin for improving the loading and release of doxorubicin in the nanopaticles

Chitosan‐graft‐β‐cyclodextrin (CS‐g‐β‐CD) copolymer was synthesized by conjugating β‐cyclodextrins to chitosan molecules through click chemistry. The copolymer structure was characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). CS‐g‐β‐CD/CMC nanoparticles were prepared by a polyelectrolyte complexation process in aqueous solution between CS‐g‐β‐CD copolymer and carboxymethyl chitosan (CMC), which was used to load anticancer drug (Doxorubicin hydrochloride, DOX·HCl) with hydrophobic group. The particle size, surface charge, zeta potential, and morphology of the nanoparticles were characterized with dynamic light scattering. The drug loading efficiency and in vitro release of DOX·HCl of the nanoparticles were measured by ultraviolet spectrophotometer. The results demonstrated that the size, surface charge and drug loading efficiency of the nanoparticles could be modulated by the fabrication conditions. The drug loading efficiency of CS‐g‐β‐CD/CMC nanoparticles was improved from 52.7% to 88.1% because of the presence of β‐CD moieties with hydrophobic cavities, which can form inclusion complexes with the drug molecules. The in vitro release results showed that the CS‐g‐β‐CD/CMC nanoparticles released DOX·HCl in a controlled manner, importantly overcoming the initial burst effect. These nanoparticles possess much potential to be developed as anticancer drug delivery systems, especially those drugs with hydrophobic group. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41034.     

林可霉素发酵液组合连续絮凝

用组合连续絮凝法及容器实验絮凝法对林可霉素发酵液进行絮凝分离研究.容器实验絮凝法结果显示：阳离子型聚丙烯酰胺絮凝分离效果优于壳聚糖和草酸,其最佳浓度为70 mg•L^-1,此时絮体沉降速率比用草酸时高24%,过滤速率高31%.组合连续絮凝法是对容器实验絮凝法的改进,其实验路线为：泵和管道输送发酵液→絮凝剂和发酵液在混合器中混合→絮凝柱连续流动絮凝→分离器固液分离.絮凝柱流量1 L•min^-1,平均停留时间10 min,pH为3,温度20℃,阳离子型聚丙烯酰胺浓度70 mg•L^-1.结果显示：组合连续絮凝法比容器实验絮凝法的沉降速率提高46%,过滤速率提高67%.该结果为工业发酵液高效过滤分离及高效离心分离提供了重要依据.     

Synthesis,characterization and application of novel polyacrylamide‐grafted barley

Polyacrylamide‐grafted barley (BAR‐g‐PAM) was synthesized by ceric ion‐based conventional method. The grafting of polyacrylamide chains on the polysaccharide backbone was confirmed through various physicochemical techniques such as intrinsic viscosity measurement, ¹³C‐NMR spectra, FTIR spectroscopy, elemental analysis, scanning electron microscopy morphology, thermogravimetric analysis study, number‐average molecular weight, and aqueous solubility. Furthermore, flocculation efficacy of the graft copolymers was studied in coal fine suspension through “jar test” procedure, toward its possible application as a novel flocculant for treatment of coal washery effluent. BAR‐g‐PAM is reported as a novel flocculant that can be used for bulk treatment of coal washery effluents. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41046.     

Highly concentrated cationic flocculants based on 80/20 wt % [2‐(acryloyloxy)ethyl]trimethylammonium chloride/acrylamide in an inverse microemulsion: Influence of the copolymerization variables on the flocculation performance

The influence of the total comonomer concentration (TCC; 30–42 wt %), emulsifier concentration (EC; 7.3–23 wt %), hydrophilic–lipophilic balance (HLB; 9–9.9), crosslinking agent (N,N′‐methylene bisacrylamide) concentration (CAC; 0–122.8 ppm with respect to TCC), and isopropyl alcohol (chain‐transfer agent) concentration (IPC; 0–1.5 wt % with respect to TCC) on the flocculation performance (FP) of 80/20 wt % acrylamide (AM)/[2‐(acryloyloxy)ethyl]trimethylammonium chloride (ADQUAT) copolymers obtained by semicontinuous inverse microemulsion copolymerization was studied with capillary suction time testing for FP assessment on anaerobic digested sludges. FP increased as TCC decreased, was nearly unaffected by EC, was maximum with an HLB of 9.5, decreased strongly with CAC, and showed a peak value with an IPC of 1 wt %. At a very high TCC, copolymer growth in a highly collapsed state resulted in greatly structured, high weight‐average molar mass flocculants with decreased swelling capacities (SCs), which did not favor bridging flocculation, and in increased shielding of their positive charges, which did not favor charge neutralization flocculation. However, industrially needed latices with both high TCC and good FP could be obtained by the addition of isopropyl alcohol, which, below a concentration of 1 wt %, improved FP by decreasing the weight‐average molar mass and thereby enhancing SC while maintaining long enough chains to be effective for bridging flocculation. On the basis of the results, new star‐shaped ADQUAT/AM copolymers are envisioned as flocculants with superior FP. A synthetic route is proposed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009