In order to offer new tools for developing structure-property relationships for intramolecular associative polymers (polysoaps), the synthesis of three families of comb-like amphiphilic cationic polymers with great structure variability is described. These polymers with amphiphilic repeating units are polyacryl or methacrylamides laterally substituted by a group containing a quaternary ammonium site and a hydrophobic alkyl side chain with 10-16 carbon atoms. Two complementary synthesis methods were developed successfully. In the first method, the tertiary amine groups of neutral polymer precursors were quaternised with various n-alkyl bromides. Five polymers were obtained in this way. On the contrary, the second method consisted of synthesizing first amphiphilic cationic acryl or methacrylamide monomers. The 11 monomers thus obtained were then polymerised by conventional free radical polymerisation in solution. The polymers obtained by both methods only differed in their molecular weights, the second method leading to much higher molecular weights (up to 2 × 106 g/mol). A preliminary investigation of the properties of a few of these polymers in solution showed interesting amphiphilic behaviour. The variation of the reduced viscosity of hydro-methanolic polymer solutions with polymer concentration revealed a strong intramolecular macromolecular folding. The microdomains corresponding to the intramolecular association of the hydrophobic alkyl side chains were eventually characterised by pyrene fluorescence spectroscopy. The local polarity of the pyrene probe was considerably lowered with respect to that of the surrounding aqueous phase and was dependent upon the macromolecular structure of the amphiphilic cationic polymers. 相似文献
The formation of micelles of hexadecyltrimethylammonium chloride (CTAC) and sodium dodecylsulfate (SDS) in aqueous solutions containing charged polysaccharides was studied by steady-state and time-resolved fluorescence measurements using pyrene as a photophysical probe. Micropolarity studies using the
I1/I3 ratio of the vibronic emission bands of pyrene and the behaviour of the
IE/IM ratio between the excimer and monomer emissions show the formation of hydrophobic domains. The interactions between the polyelectrolytes and surfactants of opposite charge lead to the formation of induced pre-micelles at surfactant concentrations lower than the critical micellar concentration (cmc) of the surfactants. At similar concentrations, the
IE/IM ratio shows a peak. This aggregation process is assumed to be due to electrostatic attractions. At higher surfactant concentrations, near the critical micellar concentration, micelles with the same properties as those found in pure aqueous solution are formed. On the other hand, systems containing polyelectrolytes and surfactants of the same charge do not show this behaviour at low concentrations. The presence of long alkyl chains bound to the polyelectrolytes also induces the formation of free micelles at concentrations somewhat below the aqueous cmc. 相似文献
Summary: The electrochemical behaviour of four types of (phenylene ethynylene)‐alt‐(phenylene vinylene) hybrid polymers, 1 , 2 , 3 , and 4 have been investigated with respect to the influence of the grafted alkoxy side chains. In the case of the fully substituted polymers 2 , 3 , and 4 , the strong insulating nature of longer linear octadecyl or bulky branched 2‐ethylhexyl side chains lowers the HOMO levels of the polymers thereby increasing the discrepancy, ΔEg, between the electrochemical, Eequation/tex2gif-stack-1.gif, and the optical, Eequation/tex2gif-stack-2.gif, bandgap energies. Thus it is not possible to establish a direct correlation between the open circuit voltage, VOC, of bulk heterojunction solar cell devices of the configuration glass substrate/ITO/PEDOT:PSS/polymer 3 :PCBM(1:3, w/w)/LiF/Al and the HOMO energy levels of polymer 3 solely, as postulated in the literature. The photovoltaic (PV) parameters greatly depend on the grafted side chains.
Linear I–V curves of solar cell devices from polymers 3a – d , measured in the dark and under 100 mW · cm−2 solar simulator illumination. 相似文献
A water-soluble terpolymer (PAVA) was synthesized by aqueous free radical copolymerization technique using acrylamide(AM), sodium 2-acrylamido-2-methylpropane-sulphonate (NaAMPS) and a macromonomer: p-vinylbenzyl-terminated octylphenoxy poly(ethylene oxide) (VPEO, degree of polymerization: 10). The remarkable intermolecular hydrophobic associations were formed in water and a brine solution for this polymer, which resulted in a good thickening effect, resistance to salt and salt-thickening. The hydrophobically associating microstructures of PAVA in aqueous solutions were measured by the fluorescent probe and scanning electron microscope. As polymer concentration was increased in water and brine solutions, the associating strength and non-polarity of hydrophobic microdomains increased remarkably. However, at the polymer concentrations higher than 0.20 g/dL, the non-polarity of hydrophobic microdomains tended to remain constant, and the I1/I3 value changed slightly in 0.5 g/dL NaCl. The continuous associating structures were formed by the expanded polymer chains in brine solutions, as well as in water. As the NaCl concentration increased, the non-polarity of associating microstructures increased slowly, but the compact degree of these microstructures increased. 相似文献
A novel functional monomer incorporating quinoline derivative moiety as the side group, 2-[4-(2,7,7-trimethyl-3-ethoxycarbonyl-5-oxo-1,4,5,6,7,8-hexhydricquinoline)phenoxyl] ethylmethacrylate (HQPEMA), was synthesized and polymerized utilizing atom transfer radical polymerization (ATRP) technique. 2-(4-Chloromethylphenyl)benzoxazole (CMPB) and CuCl/PMDETA were used as the initiator and catalyst, respectively. GPC, 1H NMR and fluorescent emission spectroscopy were conducted for characterization of polymers. The linear increase of number average molecular weight (Mn) versus conversion and the relatively narrow molecular weight distribution (Mw/Mn) of the obtained polymers confirmed that ATRP of HQPEMA was carried out successfully. In addition, the fluorescence “structural self-quenching effect” was observed in the DMF solution of the monomer HQPEMA, which bearing both electron-donating chromophore group and electron-accepting CC bond. We also found that the fluorescence properties of the newly obtained polymers containing quinoline chromophore depended on both the monomer concentration in solution and the polarity of solvents. The emission of the polymer film showed that the emission peak maxima of the polymer film shifted 50 nm towards high wavelength with respect to the polymer in DMF solution due to the intermolecular or intramolecular interactions of the polymer chains. 相似文献
One of most interesting systems of coordination polymers constructed from the first‐row transition metals is the porous ZnII coordination polymer system, but the numbers of such polymers containing N‐donor linkers are still limited. The title double‐chain‐like ZnII coordination polymer, [Ag2Zn(CN)4(C10H10N2)2]n, presents a one‐dimensional linear coordination polymer structure in which ZnII ions are linked by bridging anionic dicyanidoargentate(I) units along the crystallographic b axis and each ZnII ion is additionally coordinated by a terminal dicyanidoargentate(I) unit and two terminal 1‐benzyl‐1H‐imidazole (BZI) ligands, giving a five‐coordinated ZnII ion. Interestingly, there are strong intermolecular AgI…AgI interactions between terminal and bridging dicyanidoargentate(I) units and C—H…π interactions between the phenyl rings of BZI ligands of adjacent one‐dimensional linear chains, providing a one‐dimensional linear double‐chain‐like structure. The supramolecular three‐dimensional framework is stabilized by C—H…π interactions between the phenyl rings of BZI ligands and by AgI…AgI interactions between adjacent double chains. The photoluminescence properties have been studied. 相似文献
Strong interchain interactions render unsubstituted polythiophene un‐fusible, non‐melting, and insoluble. Therefore, control of the packing structure, which has a profound effect on the optical and electronic properties of the polymer, has never been achieved. Unsubstituted polythiophene was prepared in the one‐dimensional channels of [La(1,3,5‐benzenetrisbenzoate)]n, where polymer chains form unprecedented assembly structures mediated by the host framework. It is noteworthy that the emission and carrier transport properties were drastically changed by varying the number of chains within a particular assembly. The response of the composite to additional guests is also examined as a method to use the composites as low‐concentration sensors. Our findings show that the encapsulation of polymer chains in host materials is a facile method for understanding the intrinsic properties of conjugated polymers, along with controlling and enhancing their functions. 相似文献
The surfactant effect on the lower critical solution temperature (LCST) of thermosensitive poly(organophosphazenes) with
methoxy-poly(ethylene glycol) and amino acid esters as side groups was examined in terms of molecular interactions between
the polyphosphazenes and surfactants including various anionic, cationic, and nonionic surfactants in aqueous solution. Most
of the anionic and cationic surfactants increased the LCST of the polymers: the LCST increased more sharply with increasing
length and hydrophobicity of the hydrophobic part of the surfactant molecule. The ΔLCSTs (T0.03M − T0M), the change in the LCST by addition of 0 and 0.03 M sodium dodecyl sulfate (SDS), were found to be 7.0 and 14.5 °C for the
polymers bearing ethyl esters of glycine and aspartic acid, respectively. The LCST increase of poly(organophosphazene) having
a more hydrophobic aspartic acid ethyl ester was 2 times larger compared with that of the polymer having glycine ethyl ester
as a side group. The binding behavior of SDS to the polymer bearing glycine ethyl ester as a hydrophobic group was explained
from the results of titration of the polymer solutions containing SDS with tetrapropylammonium bromide. Graphic models for
the molecular interactions of polymer/surfactant and polymer/surfactant/salt in aqueous solutions were proposed.
Received: 17 February 2000/Accepted: 25 April 2000 相似文献
A solvent responsive dynamic nanoscale metal‐organic framework (NMOF) [Zn( 1 a )(H2O)2] has been devised based on the self‐assembly of ZnII and asymmetric bola‐amphiphilic oligo‐(p‐phenyleneethynylene) (OPE) dicarboxylate linker 1 a having dodecyl and triethyleneglycolmonomethylether (TEG, polar) side chains. In THF solvent, NMOF showed nanovesicular morphology ( NMOF‐1 ) with surface decorated dodecyl chains. In water and methanol, NMOF exhibited inverse‐nanovesicle ( NMOF‐2 ) and nanoscroll ( NMOF‐3 ) morphology, respectively, with surface projected TEG chains. The pre‐formed NMOFs also unveiled reversible solvent responsive transformation of different morphologies. The flexible NMOF showed cyan emission and no cytotoxicity, allowing live cell imaging. Cisplatin (14.4 wt %) and doxorubicin (4.1 wt %) were encapsulated in NMOF‐1 by non‐covalent interactions and, in vitro and in vivo drug release was studied. The drug loaded NMOFs exhibited micromolar cytotoxicity. 相似文献
A new series of donor–acceptor co‐polymers based on benzodithiophene and quinoxaline with various side chains have been developed for polymer solar cells. The effect of the degree of branching and dimensionality of the side chains were systematically investigated on the thermal stability, optical absorption, energy levels, molecular packing, and photovoltaic performance of the resulting co‐polymers. The results indicated that the linear and 2D conjugated side chains improved the thermal stabilities and optical absorptions. The introduction of alkylthienyl side chains could efficiently lower the energy levels compared with the alkoxyl‐substituted analogues, and the branched alkoxyl side chains could deepen the HOMO levels relative to the linear alkoxyl chains. The branched alkoxyl groups induced better lamellar‐like ordering, but poorer face‐to‐face packing behavior. The 2D conjugated side chains had a negative influence on the crystalline properties of the co‐polymers. The performance of the devices indicated that the branched alkoxyl side chains improved the Voc, but decreased the Jsc and fill factor (FF). However, the 2D conjugated side chains would increase the Voc, Jsc, and FF simultaneously. For the first time, our work provides insight into molecular design strategies through side‐chain engineering to achieve efficient polymer solar cells by considering both the degree of branching and dimensionality. 相似文献
A series of tetraguanidinium tetraphenylethene (TPE) arylsulfonates with different chain lengths was prepared via ionic self-assembly of tetraguanidinium TPE chloride and the respective methyl arylsulfonates. Liquid crystalline properties were studied by differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction. Tetraguanidinium TPE arylsulfonates with chain lengths of C8–C12 displayed hexagonal columnar mesophases over a broad temperature range, while derivatives with longer chains showed oblique columnar phases. In solution all compounds displayed aggregation-induced emission behaviour. Temperature-dependent luminescence spectra of the bulk phase of the tetraguanidinium TPE arylsulfonate with C14 side chains revealed a strong luminescence both in the solid state and the oblique columnar mesophase. The emission behaviour was rationalized by a unique combination of restriction of intramolecular rotation of the TPE core, Coulomb interaction between the guanidinium cations and π–π interactions of the anionic arylsulfonate moieties. 相似文献
We synthesized cationic random amphiphilic copolymers by radical copolymerization of methacrylate monomers with cationic or hydrophobic groups and evaluated their antimicrobial and hemolytic activities. The nature of the hydrophobic groups, and polymer composition and length were systematically varied to investigate how structural parameters affect polymer activity. This allowed us to obtain the optimal composition of polymers suitable to act as non-toxic antimicrobials as well as non-selective polymeric biocides. The antimicrobial activity depends sigmoidally on the mole fraction of hydrophobic groups (fHB). The hemolytic activity increases as fHB increases and levels off at high values of fHB, especially for the high-molecular-weight polymers. Plots of HC50 values versus the number of hydrophobic side chains in a polymer chain for each polymer series showed a good correlation and linear relationship in the log–log plots. We also developed a theoretical model to analyze the hemolytic activity of polymers and demonstrated that the hemolytic activity can be described as a balance of membrane binding of polymers through partitioning of hydrophobic side chains into lipid layers and the hydrophobic collapsing of polymer chains. The study on the membrane binding of dye-labeled polymers to large, unilamellar vesicles showed that the hydrophobicity of polymers enhances their binding to lipid bilayers and induces collapse of the polymer chain in solution, reducing the apparent affinity of polymers for the membranes. 相似文献
A design for an effective molecular luminescent thermometer based on long-range electronic coupling in lanthanide coordination polymers is proposed. The coordination polymers are composed of lanthanide ions EuIII and GdIII, three anionic ligands (hexafluoroacetylacetonate), and a chrysene-based phosphine oxide bridges (6,12-bis(diphenylphosphoryl)chrysene). The zig-zag orientation of the single polymer chains induces the formation of packed coordination structures containing multiple sites for CH-F intermolecular interactions, resulting in thermal stability above 350 °C. The electronic coupling is controlled by changing the concentration of the GdIII ion in the EuIII-GdIII polymer. The emission quantum yield and the maximum relative temperature sensitivity (Sm) of emission lifetimes for the EuIII-GdIII polymer (Eu:Gd=1:1, Φtot=52 %, Sm=3.73 % K−1) were higher than those for the pure EuIII coordination polymer (Φtot=36 %, Sm=2.70 % K−1), respectively. Enhanced temperature sensing properties are caused by control of long-range electronic coupling based on phosphine oxide with chrysene framework. 相似文献
Novel conjugated materials, poly(4,8-dialkoxy-1,5-naphthalenevinylene)s (OCn-PNV, n = 4, 6, 8, and 12), have been prepared by a method similar to the Gilch procedure. The structure, optical and thermal properties of these polymers with various alkoxy side chain lengths have been evaluated by IR, UV-Vis absorption, fluorescence emission and thermogravimetric analysis. The band gap of OCn-PNV increases with increasing side chain length. Moreover, wavelengths of the photoluminescence (PL) emission peaks (λmax) of OCn-PNV solutions decrease with increasing alkoxy side chain length. This is probably due to the entanglement of long side chains that causes distortion of the conjugated main chains and thereby raises band gap of the polymer. PL λmax's of these polymers in film state are red-shifted by 14–59 nm than those in solution state. The red-shift is due to the more chain aggregations after spin coating from solution into film state and consequently the lower band gap in the film state. Besides, the polymer with shorter side chains is more thermally stable than that with longer side chains. 相似文献
Comblike polymethacrylates with oligo-oxyethylene side chains were synthesized from the commercially available monomers CH2 ? C (CH3) COO (CH2CH2O)nCH 3, the average n being 4, 8, and 22. The three polymers exhibited lower critical solution temperatures in aqueous media. Cloud points were determined as a function of the nature and concentration of salt. For salts that destabilize the polymer solutions, the cloud points decrease linearly with salt concentration, the extent of the decrease being strongly anion dependent. Salt effects on the viscosity of the polymers were measured in water, methanol, and acetonitrile. In water the viscosity decreases on adding salt, but in methanol and acetonitrile the neutral polymers are converted to polycations as cations form stable adducts with the oligo-oxyethylene side chains. The increase in viscosity is both cation and anion dependent. The general behavior of the comblike polymers resembles that reported for aqueous or methanolic salt solutions of poly (ethylene oxide) and nonionic surfactants. 相似文献