含磺酸基团的含氟嵌段共聚物的溶液性能及其应用

利用原子转移自由基聚合以及随后的磺化反应合成了一系列具有不同含氟量和磺化度的嵌段共聚物P(SSt b FNEMA) (PSSF) .通过溶液粘度和表面张力的测定 ,研究了该含氟嵌段共聚物独特的溶液行为 .实验结果表明 ,PSSF能显著降低N 甲基吡咯烷酮溶液的表面张力 .然而 ,与N 甲基吡咯烷酮溶液的表面性能不同 ,PSSF不能显著地降低水溶液的表面张力 ;当PSSF中和成钠盐后 ,水溶液的表面张力趋于一致 .进一步通过TEM、1 H NMR考察了PSSF在不同溶液中的形态 ,发现PSSF在水溶液中以核壳结构存在 ,而在N 甲基吡咯烷酮溶液中主要以胶束的形式存在 .初步考察了PSSF对聚氨酯脲 丙烯酸酯 (PUA)复合水分散液的改性效果 ,发现只需加入少量的PSSF ,就可使PUA膜的吸水率从原来的 10wt%下降到 4wt% .     

Synthesis and micellar characterization of short block length methoxy poly(ethylene glycol)-block-poly(caprolactone) diblock copolymers

A series of short block length methoxy poly(ethylene glycol)-block-poly(caprolactone) diblock copolymers was synthesized and characterized in order to assess the potential of these copolymers as a micellar drug-delivery system. Varying the caprolactone:MePEG weight ratio in the reaction mixture allowed the synthesis of diblock copolymers with a MePEG molecular weight of 750 g/mol and PCL block lengths of 2, 5 or 10 repeat units. Phase diagrams of aqueous solutions of the copolymers were constructed which displayed characteristic cloud points and Krafft points. As the degree of polymerization of PCL increased, critical micelle concentration (CMC) values decreased from 6.97 x 10(-1) to 3.38 x 10(-3) g/l, partition equilibrium coefficients (Kv) increased from 1.09 x 10(4) to 22.2 x 10(4),and hydrodynamic diameters increased from 12.2 to 19.5 nm. The micelle morphology was determined to be spherical by transmission electron microscopy.     

Phase‐transition characteristics of amphiphilic poly(2‐ethyl‐2‐oxazoline)/poly(ε‐caprolactone) block copolymers in aqueous solutions

Amphiphilic diblock and triblock copolymers of various block compositions based on hydrophilic poly(2‐ethyl‐2‐oxazoline) (PEtOz) and hydrophobic poly(ε‐caprolactone) were synthesized. The micelle formation of these block copolymers in aqueous media was confirmed by a fluorescence technique and dynamic light scattering. The critical micelle concentrations ranged from 35.5 to 4.6 mg/L for diblock copolymers and 4.7 to 9.0 mg/L for triblock copolymers, depending on the block composition. The phase‐transition behaviors of the block copolymers in concentrated aqueous solutions were investigated. When the temperature was increased, aqueous solutions of diblock and triblock copolymers exhibited gel–sol transition and precipitation, both of which were thermally reversible. The gel–sol transition‐ and precipitation temperatures were manipulated by adjustment of the block composition. As the hydrophobic portion of block copolymers became higher, a larger gel region was generated. In the presence of sodium chloride, the phase transitions were shifted to a lower temperature level. Sodium thiocyanate displaced the gel region and precipitation temperatures to a higher temperature level. The low molecular weight saccharides, such as glucose and maltose, contributed to the shift of phase‐transition temperatures to a lower temperature level, where glucose was more effective than maltose in lowering the gel–sol transition temperatures. The malonic acid that formed hydrogen bonds with the PEtOz shell of micelles was effective in lowering phase‐transition temperatures to 1.0M, above which concentration the block copolymer solutions formed complex precipitates. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2400–2408, 2000     

水溶性聚合物和两亲聚合物:14.丙烯酰胺/2-丙烯酰胺基十六烷磺酸铵无规共聚物

水溶液中用硫酸亚铁-异丙苯过氧化氢氧化还原引发体系合成了丙烯酰胺(AM)/2-丙烯酰胺基十六烷磺酸铵(AMC_(16)SNH_4)无规共聚物。用元素分析、IR、~(13)C-NMR和~1H-NMR对其进行了表征。对水溶液性质的研究结果表明,与部分水解聚丙烯酰胺相比,这种新型共聚物有着优异的耐盐性、耐温性和贮存稳定性。     

Syntheses and some spectroscopic properties of polyanions with pendant merocyanine dyes

Polymers tagged with a local pH reporter were synthesized. A methacrylate-type monomer containing a merocyanine dye residue as a reporter dye—1-(2-methacryloyloxyethyl)-4-(2-(4-hydroxyphenyl)-ethenyl)quinolinium bromide—was synthesized. Its homopolymer and copolymers with sodium 2-acrylamido-2-methylpropanesulfonate were prepared by free radical polymerization. These polymers showed a characteristic color change in aqueous solutions from yellow to red with increasing pH from acidic to basic conditions according to the acid-base equilibria of the merocyanine dye residues. Since the electrostatic potential and polarity of media have a strong effect on the acid–base equilibria, the pendant merocyanine residues are expected to serve as a reporter to provide information on the local environments around the polymer chain at which the dye molecules are incorporated.     

Novel fluoroalkyl end-capped amphiphilic diblock copolymers with pH/temperature response and self-assembly behavior

A series of fluoroalkyl end-capped diblock copolymers of poly[2-(N,N-dimethylamino)ethyl methacrylate] (PDMAEMA or PDMA) and poly[2-(N,N-diethylamino)ethyl methacrylate] (PDEAEMA or PDEA) have been synthesized via oxyanion-initiated polymerization, in which a potassium alcoholate of 4,4,5,5,6,6,7,7,7-nonafluoro-1-heptanol (NFHOK) was used as an initiator. The chemical structures of the NFHO-PDMA-b-PDEA and NFHO-PDEA-b-PDMA depended on the addition sequence of the two monomers and the feeding molar ratios of [DMA] to [DEA] during the polymerization process. These copolymers have been characterized by (1)H NMR and (19)F NMR spectroscopy and gel permeation chromatography (GPC). The aggregation behavior of these copolymers in aqueous solutions at different pH media was studied using a combination of surface tension, fluorescence probe, and transmission electron microscopy (TEM). Both diblock copolymers exhibited distinct pH/temperature-responsive properties. The critical aggregation concentrations (cacs) of these copolymers have been investigated, and the results showed that these copolymers possess excellent surface activity. Besides, these fluoroalkyl end-capped diblock copolymers showed pH-induced lower critical solution temperatures (LCSTs) in water. TEM analysis indicated that the NFHO-PDMA(30)-b-PDEA(10) diblock copolymers can self-assemble into the multicompartment micelles in aqueous solutions under basic conditions, in which the pH value is higher than the pKa values of both PDMA and PDEA homopolymers, while the NFHO-PDEA(10)-b-PDMA(30) diblock copolymers can form flowerlike micelles in basic aqueous solution.     

Synthesis and supramolecular organization of amphiphilic diblock copolymers combining poly(N,N-dimethylamino-2-ethyl methacrylate) and poly(epsilon-caprolactone)

Well-defined poly(epsilon-caprolactone) (PCL)/poly(N,N-dimethylamino-2-ethyl methacrylate (PDMAEMA) diblock copolymers were synthesized, and their self-assembly was investigated as micelles both in aqueous solutions and in thin solid deposits. The synthetic approach combines controlled ring opening polymerization (ROP) of epsilon-caprolactone (CL) and atom transfer radical polymerization (ATRP) of N,N-dimethylamino-2-ethyl methacrylate (DMAEMA). Diblock copolymers were prepared by ROP of CL initiated by (Al(OiPr)3), followed by quantitative reaction of the PCL hydroxy end-groups with bromoisobutyryl bromide. The alpha-isopropyloxy omega-2-bromoisobutyrate poly(epsilon-caprolactone) (PCL-Br) obtained was used as a macroinitiator for the ATRP of DMAEMA. The molecular characterization of those diblock copolymers was performed by 1H NMR spectroscopy and gel permeation chromatography (GPC) analysis. The self-assembly of the copolymers into micellar aggregates in aqueous media was followed with dynamic light scattering (DLS), as a function of concentration and the pH. In parallel, the morphology of the solid deposits of those micelles was examined with atomic force microscopy (AFM).     

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.     

Detection of nitroaromatic explosives based on photoluminescent polymers containing metalloles

The synthesis, spectroscopic characterization, and fluorescence quenching efficiency of polymers and copolymers containing tetraphenylsilole or tetraphenylgermole with Si-Si, Ge-Ge, and Si-Ge backbones are reported. Poly(tetraphenyl)germole, 2, was synthesized from the reduction of dichloro(tetraphenyl)germole with 2 equivs of Li. Silole-germole alternating copolymer 3 was synthesized by coupling dilithium salts of tetraphenylsilole dianion with dichloro(tetraphenyl)germole. Other tetraphenylmetallole-silane copolymers, 4-12, were synthesized through the Wurtz-type coupling of the dilithium salts of the tetraphenylmetallole dianion and corresponding dichloro(dialkyl)silanes. The molecular weights (M(w)) of these metallole-silane copolymers are in the range of 4000 approximately 6000. Detection of nitroaromatic molecules, such as nitrobenzene (NB), 2,4-dinitrotoluene (DNT), 2,4,6-trinitrotoluene (TNT), and picric acid (PA), has been explored. A linear Stern-Volmer relationship was observed for the first three analytes, but not for picric acid. Fluorescence spectra of polymetalloles or metallole-silane copolymers obtained in either toluene solutions or thin polymer films displayed no shift in the maximum of the emission wavelength. This suggests that the polymetalloles or metallole-silanes exhibit neither pi-stacking of polymer chains nor excimer formation. Fluorescence lifetimes of polymetalloles and metallole-silanes were measured both in the presence and absence of TNT, and tau(o)/tau is invariant. This requires that photoluminescence quenching occurs by a static mechanism.     

Thermoresponsive NIPAM block copolymers containing densely grafted poly(vinyl ether) brushes synthesized by a combination of living cationic polymerization and RAFT polymerization

Diblock copolymers consisting of a multibranched polymethacrylate segment with densely grafted poly[2‐(2‐methoxyethoxy)ethyl vinyl ether] pendants and a poly(N‐isopropylacrylamide) segment were synthesized by a combination of living cationic polymerization and RAFT polymerization. A macromonomer having both a poly[2‐(2‐methoxyethoxy)ethyl vinyl ether] backbone and a terminal methacryloyl group was synthesized by living cationic polymerization. The sequential RAFT copolymerizations of the macromonomer and N‐isopropylacrylamide in this order were performed in aqueous media employing 4‐cyanopentanoic acid dithiobenzoate as a chain transfer agent and 4,4′‐azobis(4‐cyanopentanoic acid) as an initiator. The obtained diblock copolymers possessed relatively narrow molecular weight distributions and controlled molecular weights. The thermoresponsive properties of these polymers were investigated. Upon heating, the aqueous solutions of the diblock copolymers exhibited two‐stage thermoresponsive properties denoted by the appearance of two cloud points, indicating that the densely grafted poly[2‐(2‐methoxyethoxy)ethyl vinyl ether] pendants and the poly(N‐isopropylacrylamide) segments independently responded to temperature. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Effect of block lengths on the association behavior of poly(l-lactic acid)/poly(ethylene glycol) (PLA–PEG–PLA) micelles in aqueous solution

A series of poly(l-lactic acid)/poly(ethylene glycol) triblock copolymers with a PLA–PEG–PLA architecture were synthesized by a ring-opening polymerization (ROP) process. The copolymers were characterized by ¹H NMR and GPC. The total number average molecular weights were in the range of 4,700–50,000, whereas the degrees of polymerization of the PLA and PEG blocks varied from 15 to 359 and from 68 to 136, respectively. The self-association of these copolymers in aqueous environment was studied by emission fluorescence spectroscopy of anilinonaphthalene probe and the critical association concentration (CAC) of the copolymers was measured. It was found that the micellization process of these copolymers was mainly determined by the length of the hydrophobic LA block, while the length of the hydrophilic PEG block had little effect. Furthermore, the low CAC values of the copolymers suggest that the copolymers form stable supramolecular structures in aqueous solutions.     

Precisely installing gold nanoparticles at the core/shell interface of micellar assemblies of triblock copolymers

Two reduction-cleavable ABA triblock copolymers possessing two disulfide linkages, PMMA-ss-PMEO₃MA-ss-PMMA and PDEA-ss-PEO-ss-PDEA were synthesized via facile substitution reactions from homopolymer precursors, where PMMA, PMEO₃MA, PDEA, and PEO represent poly(methyl methacrylate), poly(tri(ethylene glycol) monomethyl ether methacrylate, poly(2-(diethylamino)ethyl methacrylate), and poly(ethylene oxide), respectively. Spherical micelles were obtained through supramolecular self-assembly of these two triblock copolymers in aqueous solutions. The resultant micelles with abundant disulfide bonds could serve as soft templates and precisely accommodate gold nanoparticles in the core/shell interface as a result of the formation of Au-S bonds.     

温度敏感性P(MEO2MA-co-OEGMA)共聚物的合成与性质

利用原子转移自由基聚合(ATRP)方法合成了组成递变的2-甲基-2-丙烯酸-2-(2-甲氧基乙氧基)乙酯(MEO₂MA)与寡聚乙二醇甲醚甲基丙烯酸酯(OEGMA)共聚物P(MEO₂MA-co-OEGMA). 核磁共振氢谱(¹HNMR)和凝胶渗透色谱(GPC)表征了聚合物的结构、分子量及其分布. 通过测定透光率、粘度、激光粒度分析了共聚物组成对共聚物低临界溶解温度(LCST)的影响, 考察了共聚物组成、浓度、盐浓度、盐种类、温度对其溶液相行为的影响. 结果表明: 所合成的共聚物具有温度敏感性, 其LCST 可以通过合成时共聚单体MEO₂MA与OEGMA投料比的改变来调控, 随着OEGMA量的增加共聚物的LCST升高, 共聚物溶液浓度升高其LCST减小, 随盐溶液浓度的增大共聚物的LCST降低, 共聚物的LCST降低主要受盐溶液中阴离子价数的影响; HCl的引入使共聚物水溶液的LCST降低; NaOH的引入使共聚物水溶液的LCST升高.     

Control of pH- and temperature-responsive behavior of mPEG-b-PDMAEMA copolymers through polymer composition

A series of poly(ethylene glycol) monomethyl ether-block-poly(2-(dimethylamino)ethyl methacrylate) (mPEG-b-PDMAEMA) diblock copolymers were synthesized using atom transfer radical polymerization to achieve controlled polymer molecular weight and narrow molecular weight distribution. The thermoresponsive properties of the mPEG-b-PDMAEMA diblock copolymers in aqueous buffered solutions were determined using UV-Visible spectroscopy and dynamic light scattering. The cloud point, a soluble-to-insoluble transition, was observed for all mPEG-b-PDMAEMA diblock copolymer solutions. Increasing either the mPEG or PDMAEMA molecular weight resulted in a decrease in observed cloud points as a function of pH and polymer concentration. Changing the mPEG molecular weight determined whether a second, higher temperature, thermal transition was observed as a function of pH and polymer concentration. Controlling the thermoresponsive properties of mPEG-b-PDMAEMA diblock copolymers through polymer composition, concentration, and pH enables the tailoring of these copolymers for applications ranging from non-viral gene delivery to use as a strengthening agent in paper.     

Self-assembly of pH-sensitive random copolymers: poly(styrene-co-4-vinylpyridine)

A series of pH-sensitive random copolymers, poly(styrene-co-4-vinylpyridine) (PSVP), with molecular weight about 10,000 and 4-vinylpyridine molar contents of 19-53%, were conveniently synthesized by free radical polymerization. The copolymers experience the formation, swell, and dissociation of multichain nanoparticles when the pH of the aqueous solutions/dispersions changes from 5.1 to 1.0. The nanoparticles have hydrodynamic diameters around 100 nm, a spherical shape, and a relatively uniform structure in a pH range of about 5-3 and a multicore structure at lower pH. The random distribution of the building units causes some of the hydrophilic units, protonated 4-vinylpyridine groups, to be trapped inside the nanoparticles. So the hydrophobicity of the nanoparticles is tunable by changing the 4-vinylpyridine content in the copolymers. For the copolymers with higher 4-vinylpyridine molar content, the pH range in which the multichain nanoparticles form shifts to higher values, the multichain nanoparticles dissociate, and the copolymers form single-chain hydrophobic domains at low pH.     

Water-soluble graft copolymers from macromonomer method

Water-soluble graft copolymers of well-defined structure having hydrophobic polymethacrylate branches with different ester groups were prepared by the macromonomer method. Methacrylate macromonomers of controlled molecular weights having a methacryloyloxyl end group were synthesized by radical polymerization of the corresponding monomer in the presence of thioglycolic acid followed by the reaction of glycidyl methacrylate with the terminal carboxyl group. These macromonomers were copolymerized with methacrylic acid and methyl methacrylate to prepare tailor-made graft copolymers composed of a hydrophlic backbone and different kinds of hydrophobic branches, which were characterized by elemental analysis, NMR, and GPC. The viscosities of the aqueous solutions of the sodium salts of these graft copolymers were measured. It was found that the viscosity of the dilute solution of the graft copolymer was remarkably high compared with the corresponding random copolymer irrespective of the ester group in branch segments. Solubilizing behavior of Orange-OT in aqueous solutions of the graft copolymers and the random copolymer were also investigated to study the nature of the hydrophobic domain of the graft copolymers.     

Synthesis of Amphiphilic Graft Copolymers with Poly(2‐methyl‐2‐oxazoline) Side Chains and a Backbone Containing Chloromethylstyrene and Methyl Methacrylate

New amphiphilic graft copolymers were synthesized by means of a cationic ring‐opening polymerization of 2‐methyl‐2‐oxazoline initiated with a statistical copolymer of methyl methacrylate and chloromethylstyrene. The synthesis was carried out in benzonitrile at 110°C. The grafting reaction was quantitative and the yield of grafting was more than 90%percent;. The graft copolymers were characterized by means of NMR, FT‐IR, and UV‐VIS spectroscopy, as well as elemental analysis and viscosity measurements of their aqueous solutions. The graft copolymers revealed amphiphilic properties and evidence for the formation of micelles and molecular aggregates in aqueous solution. Graft copolymers with relatively short lateral chains are soluble in methanol but insoluble in water, while the copolymers with longer lateral chains are soluble in both methanol and water.     

Multicenter polyester initiators for the synthesis of graft copolymers with oligo(2-ethyl-2-oxazoline) side chains

Multicenter alkylene-aromatic polyester initiators for the cationic polymerization of oxazolines are synthesized via the high-temperature polycondensation of 2-[4-(2-Br-ethyl)]phenylsulfonyl hydroquinone with 4,4'- (alkanoyldioxydibenzoyl)dichlorides. The Kuhn segment values, liquid-crystalline properties, and molecularmass characteristics of the macroinitiators are determined. It is shown that the obtained polyesters may be used as initiators for the cationic polymerization of 2-ethyl-2-oxazoline. The graft copolymers form aqueous micellar solutions with a narrow particle-size distribution and possess a lower critical solution temperature.     

Poly(2-[dimethylamino]ethyl methacrylate)-b-poly(hydroxypropyl methacrylate)/DNA polyplexes in aqueous solutions

This study involves the investigation of the complexation ability of poly(2-[dimethylamino]ethyl methacrylate)-b-poly(hydroxypropyl methacrylate) (PDMAEMA-b-PHPMA) amphiphilic pH and thermoresponsive block copolymers, and their quaternized counterparts QPDMAEMA-b-PHPMA, toward short DNA in aqueous solutions. The PDMAEMA-b-PHPMA amphiphilic block copolymers present various self-assembly characteristics when inserted into aqueous media, depending on the composition, the solubilization protocol, the acidity and the temperature of the aqueous media. Copolymer aggregates-DNA interactions and nanostructure formation after complexation are investigated by dynamic light scattering and intensity measurements in aqueous solutions in a fixed temperature range, utilizing two different solubilization protocols for the copolymers. Ethidium bromide assays by fluorescence spectroscopy and ζ-potential measurements were also utilized to investigate the structure and properties of the DNA/copolymer polyplexes. The interpretation of such physicochemical characterization provides extra comprehension of the novel (Q)PDMAEMA-b-PHPMA copolymers self-assembly characteristics and assesses their ability for DNA complexation, stabilization, and delivery.     

丙烯酰胺-苯乙烯双亲嵌段共聚物水溶液的表面活性及增溶性

在微乳液介质中制备了系列的丙烯酰胺 (AM)与苯乙烯 (St)的双亲嵌段共聚物 (PAM b PSt) ,用紫外分光光度法测定了共聚物的组成 ,用乌氏粘度计测定了共聚物的特性粘数 [η],并用其相对表征共聚物的分子量大小 .重点研究了双亲嵌段共聚物 (PAM b PSt)疏水链段在水溶液中的缔合行为、共聚物的表面活性及其对有机物的增溶性能 ,考察了共聚物分子组成 (疏水链段含量 )与分子量对其表面活性与增溶性能的影响规律 .研究结果表明 ,由于疏水链段的憎水性 ,PAM b PSt的分子链在水溶液表面会形成表面吸附 ,从而降低水溶液的表面张力 ;而在水溶液中 ,在疏水相互作用下 ,PAM b PSt分子链中的苯乙烯疏水链段会形成分子间或分子内的胶束 ,烃类有机物可增溶其中 ;疏水链段含量越大 ,分子量越小 ,PAM b PSt的表面活性与增溶性能越强