Novel amphiphilic network polymers consisting of nonpolar,short primary polymer chains and polar,long crosslink units: Influence of characteristic dangling chains on swelling behavior of resulting amphiphilic gels

Novel amphiphilic network polymers consisting of nonpolar, short primary polymer chains and polar, long crosslink units were prepared, and the swelling behavior of resulting amphiphilic gels is discussed by focusing on the influence of characteristic dangling chains; that is, benzyl methacrylate (BzMA) was copolymerized with tricosaethylene glycol dimethacrylate [CH₂?C(CH₃)CO(OCH₂CH₂)₂₃OCOC(CH₃)?CH₂, PEGDMA‐23] in the presence of lauryl mercaptan as a chain‐transfer agent because BzMA forms nonpolar, short primary polymer chains and PEGDMA‐23 as a crosslinker contains a polar, long poly(oxyethylene) unit. The enhanced incorporation of dangling chains into the network polymer was brought by shortening the primary polymer chain length, and copolymerization with methoxytricosaethylene glycol methacrylate, a mono‐ene counterpart of PEGDMA‐23, enforced the incorporation of flexible dangling poly(oxyethylene) chains into the network polymer, although the former dangling chains as terminal parts of primary poly(BzMA) chains were rather rigid. Then, the influence of characteristic dangling chains on the swelling behavior of amphiphilic gels was examined in mixed solvents consisting of nonpolar t‐butylbenzene and polar methanol. The profiles of the solvent‐component dependencies of the swelling ratios were characteristic of amphiphilic gels. The introduction of dangling poly(oxyethylene) chains led not only to an increased swelling ratio but also to sharpened swelling behavior of amphiphilic gels. The swelling response of amphiphilic gels was checked by changing the external solvent polarity. The dangling chains with freely mobile end segments influenced the swelling response of gels. The amphiphilic gels with less entangled, collapsed crosslink units exhibited faster swelling response than the ones with more entangled, collapsed primary polymer chains. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2192–2201, 2004     

Solution behavior of random copolymers of styrene with sodium-2-acrylamido-2-methylpropane sulfonate

The nonaqueous solution behavior of random copolymers of styrene (ST) with sodium-2-acrylamido-2-methylpropane sulfonate (Na-AMPS) [poly(ST-Na-AMPS)] has been investigated using the transient electric birefringence (TEB) technique. The copolymers with varying high sulfonate contents (about 30–70 mol%), bridging the gap between conventional ionomers and classical polyelectrolytes, were dissolved in the solvent methylformamide (MFA) with a high permittivity ? of ca. 190. The solutions showed a negative birefringence at electric field strength E of the order of kV/cm. A typical Kerr effect was observed at low polymer concentrations C of ca. 10^?3g/mL and electric field strengths of the order of kV/cm. However, the detailed, TEB studies demonstrated different behavior at two concentration regimes in dilute solution. At a low concentration regime (e.g., C ≤ 1 × 10^?3g/mL for the copolymer with a 66.7 mol % sulfonate content) where the reduced viscosity exhibited a pronounced polyelectrolyte effect, the birefringence signal pattern showed a maximum before reaching a steady value. Additionally, during the rise at an applied electric field strength beyond a threshold value, it was observed that the nonexponential field-free decay was slower than the single exponential field-induced rise. The observed anomalous behavior was similar to those of a polyelectrolyte [sodium poly (styrene sulfonate)] in aqueous solution and might be attributed to the perturbation of the molecular shape by the applied electric field. At the higher concentration regime (e.g., C ≥ 4 × 10^?3g/mL for the same copolymer with a 66.7 mol % sulfonate content) where the polyelectrolyte effects started to diminish as indicated by the viscosity study, the birefringence shape showed no variation with an increased electric field strength and the field-free decay turned out to be faster than the single exponential rise. The dissociation of ionic aggregates was tentatively interpreted to be responsible for this observation. It seems that by simply varying the polymer concentration, poly (ST-Na-AMPS) could behave either as a polyelectrolyte or as an ionomer in a single polar organic solvent.     

Bilayer Molecular Assembly at a Solid/Liquid Interface as Triggered by a Mild Electric Field

The construction of a spatially defined assembly of molecular building blocks, especially in the vertical direction, presents a great challenge for surface molecular engineering. Herein, we demonstrate that an electric field applied between an STM tip and a substrate triggered the formation of a bilayer structure at the solid–liquid interface. In contrast to the typical high electric‐field strength (10⁹ V m^?1) used to induce structural transitions in supramolecular assemblies, a mild electric field (10⁵ V m^?1) triggered the formation of a bilayer structure of a polar molecule on top of a nanoporous network of trimesic acid on graphite. The bilayer structure was transformed into a monolayer kagome structure by changing the polarity of the electric field. This tailored formation and large‐scale phase transformation of a molecular assembly in the perpendicular dimension by a mild electric field opens perspectives for the manipulation of surface molecular nanoarchitectures.     

Control of SWNT Dispersion by Block Copolymers with a Side‐Chain Polarity Modifier

The dispersion of single‐walled carbon nanotubes (SWNTs) in a non‐polar solvent is controlled with a series of polystyrene‐block‐polybutadiene‐block‐polystyrene (PSBS) block copolymers that contain cholesteryl chloroformate (CC) in side‐chains. Esterification of CC with the partially hydroxylated polybutadiene (PB) blocks allows one to tune the polarity of the block copolymers, which decreases with the amount of CC attached. An excellent dispersion of weak polar SWNTs is observed with PSBS that contains a partially hydroxylated PB block. The dispersion is then significantly deteriorated when the amount of non‐polar CC moieties increases in the block copolymers. A good dispersion is achieved with a polymer that gives rise to strong SWNT–polymer interactions, which ensures contact of the polymer molecules with the nanotube surface, rather than a good solubility of the polymer dispersant in solvent. The stability of the SWNTs in solution arises from unique needle‐like nanowires of the block copolymer aligned perpendicular to the nanotube axis.

     

Can a Proton be Encapsulated in Tetraamido/Diamino Quaternized Macrocycles in Aqueous Solution and Electric Field?

The proton‐binding behavior of solvated tetraamido/diamino quaternized macrocyclic compounds with rigid phenyl and flexible phenyl bridges in the absence or presence of an external electric field is investigated by molecular dynamics simulation. The proton can be held through H‐bonding interactions with the two carbonyl oxygen atoms in macrocycles containing rigid (phenyl) and flexible (propyl) bridges. The solute–solvent H‐bonding interactions cause the macrocyclic backbones to twist to different extents, depending on the different bridges. The macrocycle with the rigid phenyl linkages folds into a cuplike shape due to π–π interaction, while the propyl analogue still maintains the ellipsoidal ringlike shape with just a slight distortion. The potential energy required for proton transfer is larger in the phenyl‐containing macrocycle than in the compound with propyl units. When an external electric field with a strength of 2.5 V nm^?1 is exerted along the carbonyl oxygen atoms, a difference in proton encircling is exhibited for macrocycles with rigid and flexible bridges. In contrast to encapsulation of a proton in the propyl analogue, the intermolecular solute–solvent H‐bonding and intramolecular π–π stacking between the two rigid phenyl spacers leads to loss of the proton from the highly distorted cuplike macrocycle with phenyl bridges. The competition between intra‐ and intermolecular interactions governs the behavior of proton encircling in macrocycles.     

Birefringence and dielectric relaxation decay transients and anisotropic rotational diffusion of macromolecules in a strong external electric field

The decay transient response of polar and polarizable rigid bodies (macromolecules) diluted in a nonpolar solvent after a sudden switch-off of a strong external dc field is evaluated in the context of the anisotropic noninertial rotational diffusion model. On solving the differential-recurrence equations for the statistical moments (expectation values of Wigner's D functions), the decay transients of the birefringence and dielectric relaxation are obtained. The solutions (valid for arbitrary strengths of an external electric field) are given in a closed form suitable for comparison with experiment and Brownian dynamics simulations.     

Synergistic Effects of External Electric Field and Solvent Vapor Annealing with Different Polarities to Enhance β-Phase and Carrier Mobility of the Poly(9,9-dioctylfluorene) Films

In this work, the synergistic effects of external electric field(EEF) and solvent vapor annealing to enhance β-phase and carrier mobility of poly(9,9-dioctylfluorene)(PFO) films were investigated. It is found that EEF can promote the PFO β-phase conformation transition and orientate the PFO chains along the EEF direction with the assistance of polar solvent vapor annealing. PFO chain orderness is closely related to the solvent polarity. In particular, the β-phase content in the annealed film of strong polar chloroform vapor increases from 18.7% to 34.9% after EEF treatment. Meanwhile a characteristic needle-like crystal is formed in the film, as a result, the hole mobility is enhanced by an order of magnitude. The mechanism can be attributed to the fast polarization of solvent dipole under the action of EEF, thus forming a driving force that greatly facilitates the orientation of PFO dipole unit. Research also reveals that EEF driving of the PFO chains does not occur with an insoluble solvent vapor since the solvent molecules cannot swell the film, thus there is insufficient free volume for PFO chains to adjust their conformation. This research enriches the understanding of the relationship between solvent vapor annealing and EEF in orientation polymers, and this method is simple and controlled, and capable of integrating into large-area thin film process, which provides new insights to manufacture low-cost and highly ordered polymer films, and is of great significance to enhance carrier mobility and efficiency of photoelectric devices based on polymer condensed matter physics.     

A comparative study of the properties of polar and nonpolar solvent/solute/polystyrene solutions in microwave fields via molecular dynamics

The influence of an applied microwave field on the dynamics of methylamine-dichloromethane (DCM) mixtures bound within atactic polystyrene (a-PS) over a range of polymer densities from 30 to 94 wt % polymer was examined using atomistic molecular dynamics simulations. This study is an extension of previous studies on methylamine transport in relatively polar polystyrene solutions of methanol and dimethylformamide [M. J. Purdue et al., J. Chem. Phys. 124, 204904 (2006)]. A direct comparison is made across the three types of polystyrene solutions. Consideration is given to both solvent and reagent transport within the polymer solutions under zero-field conditions and in an external electromagnetic field in the canonical ensemble (NVT) at 298.0 K. Various frequencies up to 10(4) GHz and a rms electric field intensity of 0.1 VA were applied. The simulation studies were validated by comparison of the simulated zero-field self-diffusion coefficients of DCM in a-PS with those obtained using pulsed-gradient spin-echo NMR spectrometry. Athermal effects of microwave fields on solute transport behavior within polymer solutions are discussed.     

Solvent Adaptive Dynamic Metal‐Organic Soft Hybrid for Imaging and Biological Delivery

A solvent responsive dynamic nanoscale metal‐organic framework (NMOF) [Zn( 1 a )(H₂O)₂] has been devised based on the self‐assembly of Zn^II 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.     

Sorption and diffusion of methanol and water in PVDF‐g‐PSSA and Nafion® 117 polymer electrolyte membranes

Sorption and diffusion properties of poly(vinylidene fluoride)‐graft‐poly(styrene sulfonic acid) (PVDF‐g‐PSSA) and Nafion® 117 polymer electrolyte membranes were studied in water/methanol mixtures. The two types of membranes were found to have different sorption properties. The Nafion 117 membrane was found to have a maximum in‐solvent uptake around 0.4 to 0.6 mole fraction of methanol, while the PVDF‐g‐PSSA membranes took up less solvent with increasing methanol concentration. The proton NMR spectra were recorded for membranes immersed in deuterated water/methanol mixtures. The spectra showed that the hydroxyl protons inside the membrane exhibit resonance lines different from the resonance lines of hydroxyl protons in the external solvent. The spectral features of the lines of these internal hydroxyl groups in the membranes were different in the Nafion membrane compared with the PVDF‐g‐PSSA membranes. Diffusion measurements with the pulsed field gradient NMR (PFG‐NMR) method showed that the diffusion coefficient of the internal hydroxyl groups in the solvent immersed Nafion membrane mirrors the changes in the diffusion coefficients of hydroxyl and methyl protons in the external solvent. For the PVDF‐g‐PSSA membranes, a decrease in the diffusion coefficient of the internal hydroxyl protons was seen with increasing methanol concentration. These results indicate that the morphology and chemical structure of the membranes have an effect on their solvent sorption and diffusion characteristics. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 3277–3284, 2000     

The Influence of External Electric Field on Local Orientations and Phase Transitions in Polymer Liquid Crystals (PLCs)

The starting point is our previous study of influence of the internal molecular mean field of dipole‐dipole interactions on local orientation and phase transitions in polymer liquid crystal (PLC) systems of longitudinal chains.^{[1, 2]} Electric dipoles are created by LC mesogen moieties. The longitudinal PLC is a macromolecule of consecutively copolymerized LC and flexible polymer sequences. We now amplify the model by inclusion of dipole‐external electric field interactions. We find that the external fields can seriously modify the local orientational order of the system and affect phase transition parameters dependent on that order. In particular, the external fields induce the formation of disoriented nematic phases with negative values of the second order orientation parameter 〈P₂〉 for LC sequences in the longitudinal PLCs while the first order parameter 〈P₁〉 is positive. However, some rapid decreases in 〈P₁〉 are observed at points of positive‐to‐negative transitions of 〈P₂〉; thus the LC disorientation manifests itself. The limiting case of the monomer liquid crystal (MLC) systems is included also.     

Synthesis of poly(o‐phenylenediamine) nanofiber with novel structure and properties

The poly(o‐phenylenediamine) (PoPD) was synthesized from the monomer o‐phenylenediamine in various organic solvent medium viz. dimethyl sulfoxide (DMSO), N,N‐dimethyl formamide (DMF) and methanol using ammonium per sulfate as a radical initiator. The structure just like polyaniline derivative with free ?NH functional groups of the synthesized polymers confirmed by various standard characterizations was explained from the proposed polymerization mechanism. All the synthesized polymers were completely soluble in common organic solvent like DMSO and DMF because of the presence of polar free ?NH functional groups in its structure. The formation of polymer nanofiber by reverse salting‐out process was confirmed, and the synthesized polymer in DMSO medium was the best polymer in terms of nano‐morphology as well as conducting properties. Interestingly, the average DC conductivity of undoped polymer film was recorded as 2.21 × 10^?6 Scm^?1 because of induced doping through self charge separation. Moreover, the conductivity of the polymer film was further increased to 1.16 × 10^?3 Scm^?1 after doping by sulfuric acid. Copyright © 2016 John Wiley & Sons, Ltd.     

Electrorheology and characterization of acrylic rubber and lead titanate composite materials

Oxide one‐pot synthesis was used to synthesize a polymer precursor to lead titanate, PbTiO₃. Perovskite lead titanate, PbTiO₃, was synthesized via the sol–gel process. The dielectric constant, electrical conductivity and loss tangent of our acrylic rubber (AR71)–lead titanate (PT) composite material (AR/PT_8) were 14.15, 2.62 × 10^?7/Ω m, and 0.093, respectively, measured at 27 °C and 1000 Hz. SEM micrographs of composites between the AR71 elastomer and PbTiO₃ showed that the particles were reinforced within the matrix. The electrorheological properties of the AR71/PT composites were investigated as functions of electric field strength from 0 to 2 kV/mm and PbTiO₃ particle volume fraction. The storage modulus increased linearly with particle volume fraction, with or without an electric field. Without an electric field, the particles merely acted as a filler to absorb or store additional stress. With the electric field on, particle‐induced dipole moments were generated, leading to interparticle interactions, and thus a substantial increase in storage modulus. With PbTiO₃ particle volume fractions as small as 10^?4 embedded in the elastomer matrix, the modulus increased by nearly a factor of 2 as the electric field strength varied from 0 to 2 kV/mm. Copyright © 2008 John Wiley & Sons, Ltd.     

An ultrafast and clean method to manufacture poly(vinyl alcohol) bead foam products

Poly (vinyl alcohol) (PVA) foam is a promising environment‐friendly packaging material due to the good biodegradability and excellent mechanical properties. Besides, PVA can be produced on a large scale viathe non‐petroleum routes. However, the preparation of complex‐shaped PVA foam products has not been realized, because PVA is a water‐soluble and semi‐crystalline polymer with a high melting temperature (226°C), which cannot be welded through the conventional bead foaming technology. In this article, a clean and efficient strategy based on microwave foaming and sintering was innovatively developed to manufacture the PVA bead foam products. First, the expandable PVA beads were prepared through polar solvent‐plasticization, followed by supercritical carbon dioxide (scCO₂)‐impregnation in solid‐state. The impregnated beads were then surface plasticized with polar solvent by simple coating. Thus, the incorporated polar solvent in the internal and superficial regions of PVA beads was rapidly heated upon exposure to the microwave irradiation, which simultaneously induced the CO₂ foaming and interfacial melting, respectively. In this way, the expansion and welding of PVA beads were completed in a one‐step procedure. Meanwhile, the complex‐shaped PVA bead foam products with excellent elasticity and intra‐bead adhesive strength were prepared within a short period of 30 seconds. Therefore, the microwave heating can be considered as an efficient strategy for preparing the high‐performance polymer bead foam products, especially for these high‐melting temperature or glass‐transition temperature polymers.     

A novel gas sensor from polymer‐grafted carbon black: responsiveness of electric resistance of conducting composite from LDPE and PE‐b‐PEO‐grafted carbon black in various vapors

The composite of low‐density polyethylene (LDPE) filled with carbon black (CB) having high dispersibility and stability was successfully obtained by the use of poly(ethylene‐block‐ethylene oxide) (PE‐b‐PEO)‐grafted CB. The response of the electric resistance of the composite against solvent vapors was examined. The electric resistance drastically increased by 10⁴–10⁶ times the initial resistance in a nonpolar solvent vapor such as cyclohexane, and carbon tetrachloride vapor at 40 °C and returned immediately to its initial resistance when the composite was transferred to dry air. However, the electric resistance increased only several times in the polar solvent vapor, such as water and alcohol, at the same temperature. The responsiveness of electric resistance is excellently reproducible and is also stable in cyclohexane vapor and dry air. The effect of temperature on the responsiveness against cyclohexane vapor is also discussed. It is concluded that the composite of LDPE filled with PE‐b‐PEO‐grafted CB could be a promising material to use when preparing gas sensors. Copyright © 2000 John Wiley & Sons, Ltd.     

Brute Force Orientation of Matrix‐Isolated Molecules: Reversible Reorientation of Formaldehyde in an Argon Matrix toward Perfect Alignment

Brute force orientation by an electric field is a promising way of controlling the orientation of polar molecules in the gas phase, but its application to condensed‐phase molecules has been very limited. We studied the reorientation of formaldehyde molecules in a solid Ar matrix under the influence of a strong electric field using reflection absorption infrared spectroscopy. Asymptotically perfect alignment of the formaldehyde molecules along the field was achieved at field strengths exceeding 1×10⁸ V m⁻¹. The vibrational bands of the aligned molecules exhibited a unidirectional Stark shift proportional to the field strength. The reorientation of the molecules was reversible despite the cryogenic solid environment of the system.     

Electrocoagulation of waterborne polymers in the presence of carbon black

Electrodeposition of paint is an electrochemical process, starting from water-borne polymers. The electrode reactions are water decomposition, leading to diffusion layers of an extreme pH. Coagulation of polymers proceeds in these layers as an acid / base reaction rather than as a direct discharge of macroions at the electrodes. The electrodeposited film behaves like a weak acid or alkaline ion exchanger. Under polarization, high electric field strength leads to charge separation and the formation of a double space charge. Current / voltage-behavior is nonlinear. The mechanism of charge transport is purely ionic. Resistivities are in the order of p = 10⁸ Ohm·cm in the wet film. The stoved film is an insulator. Electrodeposition of a second film is impossible. However, electrodeposition of the primary film in the presence of dispersed carbon black, studied in detail for the first time, leads to an appreciable electronic conductivity in the stoved film. ρ is in the order of 10⁵ - 10⁷ Ohm·cm even with a carbon black concentration of only a few wt.-%. This has been explained in terms of a stick percolation model and the preferential formation of transversal carbon black chains in the film. The relatively high resistivities found along these chains is due to the need of electron tunneling through ultrathin polymer films around the polymer wetted individual carbon black particles. Temperature behavior of resistivities, field effect and other proofs are given for this model. For practical application, the most important findung is the possibility of an electrodeposition of a coherent second layer and even of multilayers in the presence of only 1 - 5 wt.-% of an appropriate carbon black filler.     

Miscibility behavior and single chain properties in polymer blends: a bond fluctuation model study

Computer simulation studies on the miscibility behavior and single chain properties in binary polymer blends are reviewed. We consider blends of various architectures in order to identify important architectural parameters on a coarse grained level and study their qualitative consequences for the miscibility behavior. The phase diagram, the relation between the exchange chemical potential and the composition, and the intermolecular pair correlation functions for symmetric blends of linear chains, blends of cyclic polymers, blends with an asymmetry in cohesive energies, blends with different chain lengths, blends with distinct monomer shapes, and blends with a stiffness disparity between the components are discussed. For strictly symmetric blends the Flory‐Huggins theory becomes quantitatively correct in the long chain length limit, when the χ parameter is identified via the intermolecular pair correlation function. For small chain lengths composition fluctuations are important. They manifest themselves in 3D Ising behavior at the critical point and an upward parabolic curvature of the χ parameter from small‐angle neutron scattering close to the critical point. The ratio between the mean field estimate and the true critical temperature decreases like √χ/(ρb³) for long chain lengths. The chain conformations in the minority phase of a symmetric blend shrink as to reduce the number of energeticaly unfavorable interactions. Scaling arguments, detailed self‐consistent field calculations and Monte Carlo simulations of chains with up to 512 effective segments agree that the conformational changes decrease around the critical point like 1/√N. Other mechanisms for a composition dependence of the single chain conformations in asymmetric blends are discussed. If the constituents of the blends have non‐additive monomer shapes, one has a large positive chain‐length‐independent entropic contribution to the χ parameter. In this case the blend phase separates upon heating at a lower critical solution temperature. Upon increasing the chain length the critical temperature approaches a finite value from above. For blends with a stiffness disparity an entropic contribution of the χ parameter of the order 10^–3 is measured with high accuracy. Also the enthalpic contribution increases, because a back folding of the stiffer component is suppressed and the stiffer chains possess more intermolecular contacts. Two aspects of the single chain dynamics in blends are discussed: (a) The dynamics of short non‐entangled chains in a binary blend are studied via dynamic Monte Carlo simulations. There is hardly any coupling between the chain dynamics and the thermodynamic state of the mixture. Above the critical temperatures both the translational diffusion and the relaxation of the chain conformations are independent of the temperature. (b) Irreversible reactions of a small fraction of reactive polymers at a strongly segregated interface in a symmetric binary polymer blend are investigated. End‐functionalized homopolymers of different species react at the interface instantaneously and irreversibly to form diblock copolymers. The initial reaction rate for small reactant concentrations is time dependent and larger than expected from theory. At later times there is a depletion of the reactive chains at the interface and the reaction is determined by the flux of the chains to the interface. Pertinent off‐lattice simulations and analytical theories are briefly discussed.     

Properties of Star-Branched Polymer Chains Near a Surface

We considered two model systems of star-branched polymers near an impenetrable surface. The model chains were constructed on a simple cubic lattice. Each star polymer consisted of f = 3 arms of equal length and the total number of segments was up to 799. The excluded volume effect was included into these models only and therefore the system was studied at good solvent conditions. In the first model system polymer chain was terminally attached with one arm to the surface. The grafted arm could slide along the surface. In the second system the star-branched chain was adsorbed on the surface and the strength of adsorption was were varied. The simulations were performed using the dynamic Monte Carlo method with local changes of chain conformations. The internal and local structures of a polymer layer were determined. The lateral diffusion and internal mobility of star-branched chains were studied as a function of strength of adsorption and the chain length. The lateral diffusion and internal mobility of star-branched chains were studied as a function of strength of adsorption and the chain length. It was shown that the behavior of grafted and weakly adsorbed chains was similar to that of a free three-dimensional polymer, while the strongly adsorbed chains behave as a two-dimensional system.     

Optical, dynamic, and electro-optical properties of poly(N-acryloyl-11-aminoundecanoic acid) in solutions

The optical, electro-optical, and dynamic characteristics of poly(N-acryloyl-11-aminoundecanoic acid) in organic solvents and of the sodium salt of its monomer in water were studied via the methods of flow birefringence, equilibrium and nonequilibrium electric birefringence, and dynamic light scattering. It is shown that, in aqueous solutions, the monomer forms coarse particles of both symmetric and asymmetric shapes. The linear dimensions of these particles are estimated from the data of translational and rotational diffusion. Polymer macromolecules in organic solvents feature negative anisotropy of optical polarizability. Contributions of optical microform and macroform effects to the observed flow birefringence are analyzed in detail. The intrinsic optical anisotropy of the monomer unit of the polymer, which correlates well with the corresponding values for comb-shaped polymers of a similar structure, is estimated. It is shown that polymer molecules lack marked intrinsic permanent macromolecular dipoles and that electric birefringence in their solutions is associated with macroscopic induced dipole moments that appear during orientation of the dipole moments of polar groups in side chains of the polymer under application of an electric field.