An Alternative Way towards Preparation of Hydrophobically Associating Polyacrylamide:Chemical Post-Modification

Hydrophobically associating polyacrylamides (HAPAMs) are derivatives from polyacrylamides by incorporating a small amount of hydrophobic moieties along the water-soluble mainchain. They are now becoming a class of promising candidates as thickeners or rheology modifiers in the formulations where rheology is necessary to be regulated, such as tertiary oil recovery, drilling fluids, hydraulic fracturing and coatings. Due to association of hydrophobes in nano-domains, their aqueous solutions exhibit very interesting rheological properties and better stability against salts than the unmodified precursor, polyacrylamide.Generally, there are two synthetic routes to introduce hydrophobic portion onto water-soluble polymer chains; i.e., direct copolymerization of hydrophobic and hydrophilic monomers, and post-polymerization functionalization[1]. In the case of HAPAM polymers, a commonly accepted method is micellar copolymerization in which an appropriate surfactant is employed to solubilize both monomers. However, it is widely reported[2] that the obtained polymers via micellar polymerization are characterized by: (i) blocky distribution of the hydrophobes; (ii) compositional inhomogeneity and (iii) strong dependence of solution properties on the block length.In this work, the alternative process, i.e., chemical post-modification, is employed to synthesize HAPAM polymers by direct N-alkylation of parent polyacrylamide (Figure 1) in dimethyl sulfoxide[3,4].PAM HAPAMFig. 1 Schematic route to prepare HAPAM by direct N-alkylation of PAMIt is found that the final incorporation of hydrophobic groups is in good agreement with the feed ratio[4], in contrast with that from micellar copolymerization which always brings about composition drift. Furthermore, unique rheological responses to shear rate, salt, temperature are also evidenced[5].     

含辣素衍生结构疏水缔合聚合物PAAH的合成、表征及溶液性质

以辣素功能结构单体N-（4-羟基-3-甲氧基-苄基）-丙烯酰胺（HMBA）为疏水单体,与丙烯酰胺（AM）和2-丙烯酰胺基-2-甲基丙磺酸钠（NaAMPS）通过自由基胶束共聚,制得三元疏水缔合聚合物P（AM-NaAMPS-HMBA）（简称PAAH）. 采用紫外-可见光谱、核磁共振氢谱、热重分析及扫描电子显微镜对共聚物的结构及形貌进行表征,利用原子力显微镜对聚合物水溶液的微观形貌进行观察,并对其溶解性、疏水缔合性、耐温性及抑菌性能进行了研究. 结果表明,所得共聚物中疏水单体含量与投料比基本一致;PAAH具有良好的速溶性,当聚合物浓度超过一定值后,溶液黏度急剧增加,且随着疏水单体含量增加,疏水缔合性能增强;原子力显微镜观察证实了聚合物水溶液中网络结构的存在. 与未改性的P（AM-NaAMPS）（简称PAA）共聚物相比,引入具有生物活性且带有刚性苯环结构的HMBA单体可使PAAH共聚物热稳定性增强,耐温性能提高,并赋予其优良的抑菌性能.     

新型疏水缔合丙烯酰胺/2-苯氧乙基丙烯酸酯共聚物的合成与性质

采用胶束共聚方法合成了一种新型的疏水缔合共聚物 ,它由丙烯酰胺 (AM)和少量的 2 苯氧乙基丙烯酸酯 (POEA) (<1 0mol% )组成 ,具有良好的水溶性 .当溶液浓度超过一定值c 后 ,由于分子间的疏水缔合 ,产生很大的增粘作用 .研究了不同聚合条件下包括单体浓度、投料比和SMR值对聚合物的结构和性能的影响 .实验结果表明 ,聚合物的粘度性质和缔合行为取决于其分子量的大小、疏水单体含量及其嵌段的长度和分布 .     

孪尾疏水缔合水溶性共聚物聚(丙烯酰胺/丙烯酸钠/N,N-二己基丙烯酰胺)/十二烷基硫酸钠水溶液的粘度行为

水溶性三元共聚物;孪尾疏水缔合水溶性共聚物聚(丙烯酰胺/丙烯酸钠/N;N-二己基丙烯酰胺)/十二烷基硫酸钠水溶液的粘度行为     

表面活性含氟单体-丙烯酰胺共聚物溶液性质研究

以异佛尔酮二异氰酸酯(IPDI)、十二氟庚醇(FOH)、烯丙基聚乙二醇(APEG)合成的表面活性含氟单体(FSM)与丙烯酰胺通过水溶液聚合,制备出含氟疏水缔合聚丙烯酰胺(FPAM).用表面张力法研究了FSM的胶束化,用流变仪、动态激光光散射(DLS)和原子力显微镜(AFM)表征了FPAM溶液的流变性能、缔合结构尺寸和形态.结果表明,FSM在25℃下CMC为1.28 g.L-1,表面张力为26.77 mN.m-1.FPAM溶液属于假塑性体系,临界缔合浓度为0.660%,具有一定的耐盐性.DLS和AFM表明,在低于临界缔合浓度时FPAM溶液仍能产生大量的缔合结构,FPAM分子具有很强的疏水缔合性.     

Novel approach to synthesizing hydrophobically associating copolymer using template copolymerization: the synthesis and behaviors of acrylamide and 4-(omega-propenoyloxyethoxy) benzoic acid copolymer

Hydrophobically associating copolymers of acrylamide (AM) with a small amount of 4-(omega-propenoyloxyethoxy) benzoic acid (PEBA, <2.5%) were synthesized by template copolymerization in the presence of poly(allylammonium chloride) (PAAC) as a template in an aqueous medium. These template copolymers exhibited remarkable thickening properties due to the effective hydrophobic association, which were similar to those copolymers with a multiblock structure obtained by the micellar process. The pH of the reaction medium and the molecular weight of the template strongly influenced the thickening properties of the products. In the experimental range, the higher the PEBA content, the larger the thickening capacity of these hydrophobic copolymers. The aggregate behaviors of these copolymers were studied by fluorescence, transmission electron microscopy (TEM), and light scattering techniques. The apparent critical interpolymer aggregate concentration (cac) of the copolymer solution was about 0.5 g/dL. As the concentration of the copolymer became higher than the cac, the aggregates changed their morphology from small hollow spheres to big flower-shaped aggregates. All the above results indicated that the template copolymerization gave access to a very simple and powerful means for the preparation of hydrophobically associating copolymers and other functional polymer materials.     

含树枝体疏水缔合聚合物——聚醚树枝体改性聚丙烯酰胺的合成和性质

疏水缔合聚合物是一类含有少量疏水基团的水溶性功能高分子.在水溶液中,这类聚合物在疏水作用驱动下容易发生缔合,并伴随产生独特的缔合行为和溶液性质,因此研究这类聚合物具有重要的理论和应用意义.     

疏水缔合聚丙烯酰胺在表面活性单体胶束溶液中的制备及其流变特性

配制了表面活性单体2-丙烯酰胺基十二烷磺酸钠(NaAMC12S)与十二烷基硫酸钠(SDS)的胶束溶液,分别测定了强疏水单体N-正十二烷基丙烯酰胺(C12AM)在两种胶束溶液中的增溶性能;在此基础上,于两种胶束溶液中分别进行了丙烯酰胺(AM)与C12AM的胶束共聚合,制备了疏水缔合聚丙烯酰胺(HAPAM),它们分别为二元共聚物C12AM/AM与三元共聚物C12AM/NaAMC12S/AM;测定了两种共聚物的红外光谱;采用荧光探针法与表观粘度法重点研究了它们的疏水缔合性与流变性能.结果表明,在表面活性单体NaAMC12S的胶束溶液中,可顺利地实现AM与疏水单体的胶束共聚合,由于表面活性单体也参与了共聚合,故制得的产物为三元共聚物C12AM/NaAMC12S/AM;与在SDS胶束溶液中制备的二元共聚物C12AM/AM相比,前者的疏水缔合性更强,其强疏水缔合性以强疏水单体C12AM的贡献为主,以表面活性单体NaAMC12S的贡献为辅.     

P(AM-NVP-DMDA)疏水缔合水溶性共聚物的研究

采用自由基水溶液共聚合法制备了Ｐ（ＡＭ－ＮＶＰ－ＤＭＤＡ）疏水缔合水溶性共聚物。对共聚物的溶液性能进行了研究,包括盐效应、粘温关系、流变性能、热稳定性、与碱、表面活性剂的相互作用、稀溶液性质等。共聚物分子中由于引入了较多的疏水基团而具有较强的疏水缔合效应,在聚合物浓度较低时具有较高粘度。ＮＶＰ结构单元的引入可适当提高共聚物溶液的热稳定性。对共聚物溶液的电镜分析结果表明,在其水溶液中存在着微相分离结构,它对共聚物溶液的增粘起着重要作用。     

超临界二氧化碳中丙烯酸与苯乙烯共聚

以超临界二氧化碳为介质, 进行丙烯酸与苯乙烯共聚反应, 合成出具有疏水链段结构的改性丙烯酸聚合物. 研究了压力和投料比对聚合反应的影响. 用红外光谱、紫外光谱和核磁共振谱分析其结构及组成. 采用粘度计测定其水溶液粘度随pH值的变化. 研究结果表明, 该聚合物水溶液具有明显的疏水缔合作用.     

Hydrophobically associating polyacrylamides modified by a novel self-associative cationic monomer

<正>A series of hydrophobically associating polyacrylamides modified by small amounts(3 mol%) of a self-associative cationic monomer 4-(2-(acryloyloxy) ethoxy) benzyl tri-ethyl ammonium bromide(AEBA) as hydrophobe were synthesized by radical copolymerization in aqueous solutions without external surfactants.The resulting copolymers containing a multiblock structure exhibited a high tendency for hydrophobic association and a high thickening capacity. Solution properties and aggregation structures were investigated by viscometry and fluorescence technique.The high viscosity enhancement was found as the polymer concentration beyond a critical value c~* and strongly depended on the copolymer microstructures.The number and length of hydrophobic microblocks within the copolymer backbones could be controlled by changing the AEBA concentration in copolymerization system.Addition of salt induced more hydrophobic association and viscosity enhancement.The synthesis method used was simple and environmentally friendly without any external surfactant contamination in comparison with the conventional micellar copolymerization.     

丙烯酰胺型阴离子表面活性单体与丙烯酰胺共聚物水溶液的流变特性

以丙烯酰胺型阴离子表面活性单体2-丙烯酰胺基十四烷基磺酸钠(NaAMC14S)为共单体,与丙烯酰胺(AM)的水溶液均相共聚合,使NaAMC14S的浓度分别处于临界胶束浓度上下,分别制备了具有无规结构与微嵌段结构的两类共聚物;用红外光谱法对共聚物的结构进行了表征,使用乌氏粘度法测定了特性粘数,相对表示出了共聚物的分子量;采用荧光探针法与表观粘度法重点研究了两类共聚物的疏水缔合性与水溶液的流变特性.研究结果表明,具有微嵌段结构的共聚物具有很强的疏水缔合性,当其水溶液的浓度达0.2wt%后,表观粘度迅速提高;其水溶液的切力变稀行为具有明显的可逆性,表现出强的抗剪切性能.本研究中特别发现,具有微嵌段结构的共聚物其盐水溶液的表观粘度远高于纯水溶液的表观粘度,当共聚物浓度为0.3wt%、CaCl2浓度为2wt%时,溶液的表观粘度竟然提高了3个数量级,表现出独特的正性盐敏性(即遇盐变稠).     

Transition metal-catalyzed one-pot synthesis of water-soluble dendritic molecular nanocarriers

Here, we report the first example of transition metal-catalyzed one-pot synthesis of water-soluble dendritic molecular nanocarriers behaving like unimolecular micelles. Using the palladium-alpha-diimine chain walking catalyst, copolymerization of ethylene and comonomer 3 afforded, in one step, amphiphilic copolymer 1 having a hydrophobic core and a hydrophilic shell. A much larger amphiphilic core-shell copolymer 2 was synthesized by a two-step approach: a copolymer having many free hydroxyl groups was first prepared, which was subsequently coupled to poly(ethylene glycol) (PEG) to afford the copolymer 2. Light-scattering, fluorescence, and UV/vis spectroscopic studies with Nile Red in aqueous solution showed unimolecular micellar properties for both copolymers 1 and 2. The dye encapsulation capacity for the core-shell copolymers is nearly proportional to the molecular weight of the hydrophobic core. The unimolecular micellar properties coupled with the good water solubility and biocompatibility of the PEG moieties make these molecular nanocarriers promising candidates for many applications including drug delivery and controlled drug release.     

SET-LRP法制备星型疏水缔合水溶性聚合物

采用丙烯酰胺(AM)、2-丙烯酰胺基-2-甲基丙磺酸钠(NaAMPS)以及N-叔丁基丙烯酰胺(NtBA)为共聚单体,以Cu~0粉/三(2-二甲氨基乙基)胺(Me_6-TREN)为催化体系,四氯化碳(CCl_4)为引发剂,利用单电子转移自由基聚合(SET-LRP)方法合成星型疏水缔合水溶性聚合物P(AM/NtBA/NaAMPS)。采用控制变量法分别考察了引发温度、疏水单体含量、AMPS含量、引发剂用量、催化剂铜、单体浓度等因素对聚合物相对分子质量的影响,确定了最佳聚合条件并考察了聚合物的耐温抗盐性能。结果表明,当单体浓度为35%,引发温度为25℃,AM、AMPS、NtBA分别占单体总量的93.6%、5%、1.4%(摩尔比),引发剂质量分数为0.4942%,催化剂铜的质量分数为0.0848%,钝化剂的质量分数为0.1192%时,所得星型疏水缔合水溶性聚合物P(AM/NtBA/NaAMPS)的相对分子质量出现最高值为267万,同时具有一定的耐温抗盐性,其溶液性能与线型化的P(AM/NtBA/NaAMPS)相似,且在相同浓度下CaCl_2对聚合物表观粘度的影响比NaCl大。     

Fluorocarbon polymerizable surfactants: viscometric behavior, micellar polymerization and interactions with associating polymers

 The micellar aggregation of two fluorocarbon surfactants bearing a polymerizable acrylamido group and differing only in the degree of amido substitution (CONH or CONC₂H₅) has been investigated by viscometry. The two surfactants exhibit distinct solution properties with a micellar growth occurring at a much lower concentration for the N-monosubstituted sample which shows in addition a shear thickening and rheopectic behavior. The ability of the latter surfactant to form hydrogen bonding is responsible for this difference in behavior. Micellar copolymerization of acrylamide with these surfactants or with a hydrocarbon analogue gives copolymers with a polysoap-like behavior. The copolymers in aqueous solution show a pronounced intramolecular hydrophobic aggregation expressed by relatively low-viscosity values when compared with those of other hydrophobically modified water-soluble polymers reported in the literature. Surfactant–polymer mixed systems do not show a strong incompatibility between fluorocarbon and hydrocarbon moieties. Received: 24 March 1998 Accepted: 30 June 1998     

表活性单体NaAMCnS及其聚合物的合成及性能研究

针对疏水缔合聚合物水溶性不足的问题，本文合成了三种含烷基磺酸根的阴离子型表面活性单体2-丙烯酰胺基辛烷基磺酸钠（NaAMC₈S）、2-丙烯酰胺基十二烷基磺酸钠(NaAMC₁₂S)和2-丙烯酰胺基十八烷基磺酸钠(NaAMC₁₈S),通过氢谱、碳谱、高分辨质谱对其结构进行了表征。通过表面张力法和电导率法测定了NaAMC₈S和NaAMC₁₂S的临界胶束浓度；用荧光探针技术研究了其增溶作用；以偶氮二异丁脒盐酸盐（AIBA）为引发剂，在水溶液中研究了丙烯酰胺（AM）分别与NaAMC₈S、NaAMC₁₂S的二元共聚反应，通过控制AM与NaAMC₈S、NaAMC₁₂S的投料比制备得到两个系列聚合物P（AM/NaAMC₈S）、P(AM/NaAMC₁₂S),研究了表面活性单体含量对聚合物疏水缔合作用及耐温抗盐性能的影响。实验结果表明，NaAMC₈     

Synthesis and characterization of hydrophobically modified polyacrylamides and some observations on rheological properties

Hydrophobically modified polyacrylamide (PAM) polymers were synthesized by means of an aqueous micellar copolymerization, the di-alkyl substituted acrylamides di-n-propylacrylamide (DPAM) and di-n-octylacrylamide (DOAM) being used as hydrophobic comonomers. The number of hydrophobic blocks was varied using three different comonomer contents (f=1, 3 and 5 wt.%). The length of hydrophobic blocks, i.e. the number of hydrophobes per micelle, N_H, was controlled by the sodium dodecyl sulphate surfactant concentration. The effect of the type of hydrophobic comonomer and the number and length of hydrophobic units on the composition of the copolymer and its solubility and rheological properties were studied. The results indicate that the average copolymer composition is independent of the degree of conversion and surfactant concentration. Solubility and rheological measurements lead to a number of conclusions. First, DPAM is a weak hydrophobic monomer, all DPAM/AM (AM=acrylamide) copolymers being water soluble. Second, there is no strong hydrophobic interaction between DPAM units, in particular for low polymer concentration and N_H, and thus no strong associative thickening behaviour. Third, DOAM is a strong hydrophobic comonomer. Incorporation of a small amount of DOAM into PAM causes a dramatic enhancement in viscosity due to hydrophobic interactions. The properties of the copolymers are strongly dependent on the N_H values, most DOAM/AM copolymers being insoluble in water.     

Hydrophobically Associating Polyacrylamides Prepared by Inverse Suspension Polymerization: Synthesis,Characterization and Aqueous Solution Properties

Hydrophobically associating polyacrylamides (HAPAMs) were synthesized via inverse suspension polymerization using ammonium persulphate (APS)/tertramethylethylenediamine (TEMED) as the redox initiators, 2-methacryloyloxyethyl n-alkyl dimethyl ammonium bromide (DM-n, n = 8, 12, 16) as the hydrophobic comonomers. The structures of the copolymers were elucidated by FT-IR and ionic chromatographic analysis, respectively. The morphology and particle size of the resultant HAPAMs were characterized by scanning electronic microscope (SEM) and laser particle size analyzer, which revealed that spherical particles were formed and the particle size exhibited Gaussian distribution centered from 25 μ m to 162 μ m. Furthermore, the solution properties of the copolymers were studied with viscometry and the results showed that HAPAMs synthesized under optimal conditions exhibited an obvious viscosity enhancement in aqueous solution and excellent salt-tolerant capability in brine.     

疏水缔合水溶性聚合物的合成研究进展

综述了疏水缔合水溶性聚合物的合成的最新研究进展。主要合成方法有非均相共聚、均相共聚、胶束共聚、反相微乳液聚合、无皂乳液聚合、活性阴离子聚合以及超临界二氧化碳介质等。     

疏水缔合(丙烯酰胺十六烷基二甲基烯丙基氯化铵-2-丙烯酰胺基-2-甲基丙磺酸)三元共聚物的合成与性能研究

疏水缔合水溶性聚合物是指在聚合物亲水性大分子链上引入少量疏水基团的一类水溶性聚合物[1～5].在水溶液中,疏水基团之间由于憎水作用而发生聚集,使大分子链产生分子内与分子之间缔合.在临界缔合浓度以上,以分子间缔合为主,增大了流体力学体积,因此,具有较好的增粘作用.疏水基的加入可大幅度地改变聚合物的流变性能.在聚合物驱油中的流度控制,提高波及效率、以及调剖中起到非常重要的作用.