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Large-amplitude oscillatory shear alignment of a hierarchically ordered system of comb-shaped supramolecules and the preparation of core−corona nanorods thereof are reported. The supramolecules consist of nearly symmetric polystyrene-b-poly(4-vinylpyridine) diblock copolymers with pentadecylphenol side chains hydrogen bonded to the poly(4-vinylpyridine) blocks. The polystyrene blocks, accounting for approximately 20% (w/w) of the supramolecules, are segregated in hexagonally ordered cylinders inside a matrix formed by the comb-shaped poly(4-vinylpyridine)-based blocks. The matrix further self-organizes in a layered structure below the order−disorder transition temperature of 70 °C. Thus, a cylinder-within-lamellar morphology is formed. Imposing shear leads to considerable alignment of both structures. The cylinders align along the shear flow with the (10) plane parallel with respect to the shear plane. The matrix layers align perpendicular to the cylinders, transverse to the flow. After elimination of pentadecylphenol by dialysis, crew-cut rods of 20−25 nm in diameter and 5−10 μm in length are obtained.

We report self-organized polymer electrolytes based on poly(styrene)-block-poly(4-vinylpyridine) (PS-block-P4VP). Liquidlike ethylene oxide (EO) oligomers with sulfonic acid end groups are bonded to the P4VP block, leading to comb-shaped supramolecules with the PS-block-P4VP backbone. Lithium perchlorate (LiClO4) has been added to the EO-rich domains. Small- and wide-angle X-ray scattering in combination with Fourier transformation infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), ac impedance, and dynamic mechanical spectroscopy (DMA) suggests alternating lamellae of reinforcing glassy PS domains and ionically conducting “nanochannels” consisting of poly(4-vinylpyridinium), oligomeric ethylene oxide sulfonates, and LiClO4. The long period of the self-organization is ca. 300 Å. So far, the ionic conductivity levels remained relatively low, i.e., 10^-7−10^-6 S/cm at room temperature and 10^-5−10^-4 S/cm at 80 °C. However, as self-organization of polymeric supramolecules allows combining glassy reinforcing domains and well-plasticized domains consisting of oligomers with high segmental motions, there may exist possibilities to tune feasible combination of electrical and mechanical properties.

A quantitative theory of anionic copolymerization of an arbitrary number of monomers has been developed to calculate the rate of this process as well as the parameters characterizing the composition and chemical structure of the gradient macromolecules formed. Equations have been derived for the angular dependence of the amplitude of scattering of the melt of these copolymers as well as its spinodal. The theory elaborated for batch “living” anionic copolymerization has been extended to semibatch regimes where the reaction mixture is continuously fed by a solution of monomers. Equations have been derived providing the possibility to establish the dependence of the intramolecular inhomogeneity of the products of semibatch copolymerization on the monomer feed rate and composition. With the theoretical approach developed, it is possible to efficiently control the chemical structure of the copolymers at each stage of their synthesis which is of utmost importance for obtaining polymeric materials with desired properties.

An investigation of side chain microphase separation within a single comb copolymer molecule containing chemically different A and B side chains has been carried out. Expressions for the transition point %@mt;sys@%χ%@sx@%AB%@be@%*%@sxx@%%@mx@% in a good (%@mt;sys@%χ%@sx@%AB%@be@%*%@sxx@%%@mx@% ~ N^-3/8), marginal (%@mt;sys@%χ%@sx@%AB%@be@%*%@sxx@%%@mx@% ~ N^-1/2), θ (%@mt;sys@%χ%@sx@%AB%@be@%*%@sxx@%%@mx@% ~ N^-2/3), and poor (%@mt;sys@%χ%@sx@%AB%@be@%*%@sxx@%%@mx@% ~ N^-1) solvent are derived both by a mean field calculation and by scaling arguments. Properties of the system below and above the transition point are described. Some unusual “bowlike” conformations are predicted for a single molecule in the microphase separated state in a good solvent.

The phase behavior of a melt of monodisperse rod−coil diblocks is studied. We derive a Landau free energy functional for both a compositional and a nematic order parameter. The excluded volume interaction between the rod blocks is modeled by an attractive Maier−Saupe interaction. The incompatibility between rod and coil blocks is modeled by the usual Flory−Huggins interaction. For a large volume fraction of the rods, a transition from isotropic to nematic to smectic C is observed upon decreasing the temperature, whereas for small rod volume fraction, spherical, hexagonal, and lamellar structures prevail. In the smectic C phase, the rod orientation angle with respect to the lamellar normal increases rapidly from 35 to 40° close to the nematic/smectic-C phase boundary to values between 45 and 55°.

The microphase-separated morphology of a melt of a specific class of comb−coil diblock copolymers, consisting of an AB comb block and a linear homopolymer A block, is analyzed in the weak segregation limit. On increasing the length of the homopolymer A block, the systems go through a characteristic series of structural transitions. Starting from the pure comb copolymer, the first series of structures involve a short length scale followed by structures involving a large length scale. A maximum of two critical points exists. Furthermore, in the two parameter space characterizing the comb−coil diblock copolymer molecules considered, a nontrivial bifurcation point exists beyond which the structure factor can have two maxima (two correlation hole peaks).

A characteristic intermediate segregation type chain length dependence of the long period D of the lamellar microdomain structure of a class of comb−coil supramolecules is reported. The supramolecular comb−coil diblock copolymers studied consist of a polystyrene (PS) “coil” block and a “comb” block of poly(4-vinylpyridine) (P4VP) either hydrogen bonded to pentadecyl phenol (PDP) (i.e., P4VP(PDP)-b-PS) or first protonated with methanesulfonic acid (MSA) and then hydrogen bonded to PDP (i.e., P4VP(MSA)(PDP)-b-PS). In both cases we find a scaling D ~ %@mt;sys@%%@ital@%N%@rsf@%%@sx@%tot%@be@%δ%@sxx@%%@mx@% , δ ≅ 0.8, where Ntot denotes the total number of monomers of the P4VP-b-PS backbone. In the case of diblock copolymers this would correspond to a characteristic intermediate segregation regime behavior. Pure PS-b-P4VP, on the other hand, shows the expected strong segregation behavior D ~ %@mt;sys@%%@ital@%N%@rsf@%%@sx@%tot%@be@%δ%@sxx@%%@mx@% , δ ≅ 0.7.

Conditions for the crossover from the strong to the superstrong segregation regime are analyzed for the case of comb−coil diblock copolymers. It is shown that the critical interaction energy between the components required to induce the crossover to the superstrong segregation regime is inversely proportional to mb = 1 + n/m, where n is the degree of polymerization of the side chain and m is the distance between successive grafting points. As a result, the superstrong segregation regime, being rather rare in the case of ordinary block copolymers, has a much better chance to be realized in the case of diblock copolymers with combs grafted to one of the blocks.

In this work we present the orientational behavior of comb copolymer-like supramolecules P4VP(PDP)1.0, obtained by hydrogen bonding between poly(4-vinylpyridine) and pentadecylphenol, during large-amplitude oscillatory shear flow experiments over a broad range of frequencies (0.001−10 Hz). The alignment diagram, presenting the macroscopic alignment in T/TODT vs ω/ωc, contains three regions of parallel alignment separated by a region of perpendicular alignment. For our material, the order−disorder temperature TODT = 67 °C and ωc, the frequency above which the distortion of the chain conformation dominates the materials' viscoelasticity, is around 0.1 Hz at 61 °C. For the first time flipping from a pure transverse alignment via biaxial transverse/perpendicular alignment to a perpendicular alignment as a function of the strain amplitude was found.

Computer simulation modelling of a flexible comb copolymer with attractive interactions between the monomer units of the side chains is performed. The conditions for the coil-globule transition, induced by the increase of attractive interaction, ɛ, between side chain monomer units, are analysed for different values of the number of monomer units in the backbone, N, in the side chains, n, and between successive grafting points, m. It is shown that the coil-globule transition of such a copolymer corresponds to a first-order phase transition. The energy of attraction (ɛ) required for the realisation of the coil-globule transition decreases with increasing n and decreasing m. The coil-globule transition is accompanied by significant aggregation of side chain units. The resulting globule has a complex structure. In the case of a relatively short backbone (small value of N), the globule consists of a spherical core formed by side chains and an enveloping shell formed by the monomer units of the backbone. In the case of long copolymers (large value of N), the side chains form several spherical micelles while the backbone is wrapped on the surfaces of these micelles and between them.

Background:Persistent airflow limitation may develop in patients with asthma, particularly in adults with nonatopic (intrinsic) disease. Although the underlying mechanisms are still unknown, respiratory infections might be involved. Objective:We investigated the annual loss of lung function in relation to seropositivity to Chlamydia pneumoniaein different subgroups of patients with severe asthma according to age at onset of asthma and atopic status. Methods:One hundred one nonsmoking outpatients with a pulmonologist’s diagnosis of severe asthma (32 men and 69 women; mean age, 46.0 years; range, 18-75 years) were included in a cross-sectional study. C pneumoniae–specific serum IgG and IgA were measured by means of ELISA. The estimated decline in lung function was calculated from the relationship between postbronchodilator FEV1/vital capacity (percent predicted) and the duration of asthma and expressed as the slope of the regression line. Results:Patients with adult-onset nonatopic asthma and positive IgG antibodies to C pneumoniaehad a significantly steeper slope of the regression line compared with the other subgroups of asthmatic patients (P= .001), being indicative of a 4-fold greater estimated decline in postbronchodilator FEV1/vital capacity (2.3% vs 0.5% predicted per year of asthma duration). Conclusion:These results suggest that C pneumoniaeinfection might promote the development of persistent airflow limitation in patients with nonatopic adult-onset asthma. It remains to be established whether viable pathogens that are accessible for therapeutic intervention are still present in the lower airways. (J Allergy Clin Immunol 2001;107:449-54.)

Comb-shaped or hairy rodlike supramolecules can be obtained by hydrogen bonding rigid rod polymers and amphiphilic oligomers. Here we introduce a concept to achieve electrically conducting acid doped PANI to allow cylindrical self-organization. PANI is doped with camphorsulfonic acid (CSA) where 4-hexylresorcinol (Hres) is hydrogen bonded to form supramolecules, which further undergo self-organization. The structure formation of PANI(CSA)0.5(Hres)y complexes is discussed on the basis of small- and wide-angle X-ray scattering and electrical conductivity. Highly ordered hexagonal cylindrical structures were observed with a distance between the cylinders around 35 Å. Electrical conductivity increases 2 orders of magnitude upon formation of cylindrical structures, potentially due to confinement of PANI chains within the cylinders. The method would then allow an easy preparation of nanoscale organic conducting wires, just by mixing the components together.

Expressions are derived for the distributions in size and composition of the macromolecular products of random degradation of diblock copolymers with arbitrary block length distributions. Equations for the calculation of the angular dependence of the static structure factor of these products formed at different depths of degradation are presented. General regularities of the evolution of the spinodal of the polymer melt in the course of this reaction are analyzed. Proceeding from the general theory developed, examples concerning degradation processes of diblock copolymers with particular block length distributions are provided.

An analysis of the cylindrical brush of an isolated comb copolymer molecule, consisting of a semiflexible backbone and rodlike side chains, is presented. Using a mean-field approach and a simplyfying assumption, which is tested by computer simulations, we find that the persistence length of the brush, λ, scales as λ ∝ L²/ln L for large values of the side chain length L. In the cylindrical brush regime the order parameter of the rods is negative, implying that the rods orient normal to the cylindrical axis.

On the basis of the experimentally determined phase behavior in blends of polystyrene and random copolymers of styrene and 4-vinylpyridine, i.e., P(Sx-co-4VP1-x)/PS, the Flory−Huggins interaction parameter is demonstrated to satisfy 0.30 < χS,4VP ≤ 0.35. This value is substantially smaller than reported before. To corroborate our results, a similar study was performed using 2-vinylpyridine leading to 0.09 < χS,2VP ≤ 0.11, in excellent agreement with the well-established value of χS,2VP = 0.1.

An analysis of the cylindical brush of an isolated comb copolymer molecule consisting of a semiflexible backbone and flexible side chains is presented. Using the Alexander−de Gennes approximation, we calculate the free energy of both straight and bent cylindrical brush and the brush persistence length λ, and show that λ scales as a function of the side chain length M as λ ∝ M². The discrepancy between the asymptotic scaling behavior and recent computer simulation results is also discussed.

Macroscopic orientation of self-organized supramolecular polymeric materials has been demonstrated by oscillatory shear flow using in-situ small-angle X-ray scattering (SAXS). In the case when a homopolymer poly(4-vinylpyridine) and pentadecylphenol molecules are stoichiometrically complexed to form comb copolymer-like supermolecules, the self-organized lamellar local structures align parallel when sheared below the order−disorder transition temperature at 56 °C using 0.5 Hz frequency and 100% strain amplitude. Therefore, the hydrogen bonds between the phenolic and pyridine groups are strong enough to withstand the applied flow. In the case of a diblock copolymer of polystyrene and poly(4-vinylpyridine) stoichiometrically complexed with pentadecylphenol molecules to form the supermolecules, the self-organization yields lamellar-within-lamellar local structure near room temperature. The larger lamellar diblock copolymer structure showed a parallel orientation relative to the shearing plates upon shearing at 125 °C (i.e., above the order−disorder transition of the short length scale comb copolymer-like structure) with initially 0.5 Hz and finally 1 Hz, both at 50% strain amplitude. On cooling, the short length scale lamellar structure, consisting of poly(4-vinylpyridine) block and pentadecylphenol, is formed inside the layers of the comb copolymer-like material in perpendicular orientation.

We contrasted the effect of instruction-induced expectancies and language intermixing in an English lexical decision task performed by Dutch–English bilinguals. At the start of the experiment, participants were instructed to respond to interlingual homographs and exclusively English words by giving a “yes” response, and to English non-words and exclusively Dutch words by giving a “no” response. In the first part of the experiment the stimulus list did not contain any Dutch words. In the second part of the experiment, Dutch items were introduced. No significant differences were found between interlingual homographs and controls in the first part of the experiment, while strong inhibition effects were obtained for interlingual homographs in the second part. These results indicate that language intermixing rather than instruction-based expectancies drives the bilingual partipants' performance. Consequences for current views on bilingual word recognition are discussed.

We show that polymeric materials characterized by two length scales are obtained if diblock copolymers are mixed with amphiphilic selective solvents, leading to self-organization which combines the “block copolymer length scale” with a much shorter “nanoscale”. In this work, the amphiphilic compound is 3-n-pentadecylphenol (PDP) which is hydrogen-bonded to the pyridine group of polystyrene-block-poly(4-vinylpyridine), i.e., PS-b-P4VP. The molecular architecture resembles comb-coil diblock copolymers A-block-(B-graft-C) but is obtained using the supramolecular assembly route. The structures were determined with a combination of transmission electron microscopy and small-angle X-ray scattering. On the block copolymer scale (300 Å range), the PS blocks are microphase-separated from the P4VP(PDP)x blocks, where x denotes the ratio between the number of phenol and pyridine groups. For PS-b-P4VP block copolymers having a spherical morphology and P4VP as the minority component, the structure of PS-b-P4VP(PDP)x changes from spherical to hexagonal and further to lamellar as a function of the amount of PDP added. For all comb-coil diblock copolymer morphologies, the P4VP(PDP)x domains are further “nanophase-separated” into lamellar structures due to microphase separation of the comb copolymer-like complex between P4VP and PDP. The morphology diagram is presented for stoichiometric conditions (x = 1), using a range of different PS-b-P4VP block copolymers.

In this paper we study the phase behavior of blends of associating homopolymers A and B in the weak segregation regime. The homopolymers are “associating” in the sense that hydrogen bonds are possible between the A chains and the B chains. Hydrogen bonds between two A chains, or between two B chains, are not possible. Each B chain can form at most one hydrogen bond, whereas each A chain might form bonds with several B chains, leading to the formation of block copolymer-like clusters. If the hydrogen bonds are strong enough, the system might undergo a microphase separation transition. However, due to the reversible nature of the hydrogen bonds, the system is in dynamic equilibrium, enabling it to adapt its cluster composition to changing conditions. Therefore, to construct the phase diagram, the free energy should be minimized simultaneously with respect to the cluster composition and the parameters describing the microstructure. We show that in the weak segregation regime this minimization can be split into two independent steps. In the first step, one determines what the cluster composition would have been if the system were homogeneous. In the second step, this composition is inserted into the expression for the Landau free energy without the nonlocal term. We show that the error made in the first step (neglecting the change in cluster composition due to the presence of the microstructure) exactly cancels the error made in the second step (omission of the nonlocal term from the Landau free energy). For the simplest associating homopolymer blend the phase diagram is presented.

The solid state of comb copolymer-like systems obtained by blending poly(4-vinylpyridine) with pentadecylphenol was studied by a combination of techniques. Depending on the amount of pentadecylphenol, several regimes are present. For 0.5 ≤ x ≤ 1.0 (x is the ratio between the number of phenol and pyridine groups) the alkyl tails form an interdigitated hexagonally packed crystalline layer. Small-angle X-ray scattering measurements show that for x = 1.5 and 2.0 the excess pentadecylphenol cocrystallizes with the associated pentadecylphenol, with the free phenol groups probably aggregating near the middle of the crystalline layer. For x ≥ 2.0 the orthorhombic crystal modification also appears. Finally for x ≥ 3.0, part of the excess pentadecylphenol macrophase separates on crystallization, forming an additional phase of pure pentadecylphenol with the familiar orthorhombic packing. These findings are similar to results obtained for real comb copolymer systems, i.e., containing covalently bonded side chains. However, our systems are essentially different due to the dynamic hydrogen-bonding equilibrium, which implies that the equilibrium solid state may always involve some form of macrophase separation.

We report the results of a Monte Carlo simulation study of isolated comb copolymer cylindrical brushes. The conformational characteristics of molecules consisting of a flexible backbone densely grafted with side chains strongly depend on the rigidity of the side chains, which is exemplified by using both fully flexible and totally rigid side chains. The short length scale fluctuations of the backbone are not affected by the presence of rigid rod side chains, whereas flexible side chains induce local stretching of the backbone. However, at the large length scale, the persistence length λ of the cylindrical brush is considerably larger for rigid rod side chains than for flexible side chains. Moreover, for rigid side chains the ratio between the persistence length λ and the diameter D of the brush increases approximately linearly as a function of the rod length L, thus supporting the possibility of lyotropic behavior. In contrast to this, in the case of flexible side chains, λ/D is approximately independent of the side chain length M.

Fluctuation effects on the order−disorder transition (ODT) in correlated random copolymers (polydisperse A/B multiblock copolymers with block lengths having an exponential Flory distribution, and a large average number of blocks per chain) are studied with due regard for the strong temperature dependence of the period of the arising ordered phases, characteristic for the system under consideration. To this end, following a field theoretical variational method, the free energy is minimized with respect to both the concentration profile ψ and the correlation function G, assumed to belong to certain classes of trial functions. The trial function for G contains an extra adjustable parameter as compared to the situation typical for monodisperse A/B block copolymer melts. The shape of the correlation function and its temperature dependence are determined both for the disordered phase and for the ordered phases. In the vicinity of the critical point the phase diagram is calculated and presented in a universal form by using reduced variables. It is shown that near the ODT and for A-monomer fractions f close to ¹/2, the profiles are strongly fluctuating:  in the ordered phase the amplitude of the fluctuations is equal to the amplitude of the average profile, and in the disordered phase the concentration inhomogeneities are comparable to those in the ordered phase. In the same region the disordered phase has an anomalously large correlation length, indicating some kind of local ordering. In connection with this, we discuss the close relationship between the disordered phase and the random wave structure.

The theoretical modeling of the relaxation behavior of polymers in the glass transition region, advocated by Moynihan and co-workers, has been used to analyze the heat flow and the relaxation of polymer systems during isothermal modulated DSC experiments in the glass transition region. An analytic solution for the frequency dependent fictive temperature is obtained, which takes a particularly simple form in the high-frequency region. The maximal phase lag of the fictive temperature Tf is βπ/2, where the exponent of the stretched-exponential characterizing the enthalpy relaxation, β, is on the order of 0.1−0.7. The corresponding maximal phase lag in the heat flow is much smaller, on the order of 2−5 deg. It is once more iterated that, as observed long ago by Birge and Nagel, the loss heat capacity corresponds to the entropy production due to a redistribution of energy over the heat baths. The possibility of using specific-heat spectroscopy as a tool to determine miscibility in polymer blends whose constituents possess similar glass transition temperatures is discussed. Compared to conventional differential scanning calorimetry, the resolution is enhanced. However, in many cases an unambiguous conclusion still requires additional enthalpy relaxation of the blend induced by physical aging in the glassy state.

Dynamic mechanical spectroscopy (DMS) is used to further investigate the recently observed order−disorder transition (ODT) in comblike block copolymers obtained by hydrogen bonding between poly(4-vinylpyridine) and pentadecylphenol (P4VP−PDPx). For stoichiometric amounts of pyridine and phenol, i.e., x = 1.0, the ODT to a lamellar structure occurs at T ≃ 65 °C. The dynamic moduli G‘ and G‘‘ simultaneously show a crossover from a liquidlike behavior (G‘ ~ ω^1.5 and G‘‘ ~ ω) to a response intermediate between a Newtonian fluid and a solid (G‘ ≈ G‘‘ ~ ω^1/2). The behavior above TODT differs slightly from a homopolymer melt (G‘ ~ ω^2.0) due to composition fluctuations, whereas the behavior below TODT is characteristic for quenched block copolymer lamellar phases with local uniaxial order and global isotropy. Near room temperature, a transition to solid behavior (G ~ ω⁰) takes place due to crystallization of the alkyl side chains. Larger amounts of PDP lower the TODT temperature, and for x = 2.0 the transition to solid response occurs directly from the disordered state. Small and wide angle X-ray scattering (SAXS and WAXS) experiments and differential scanning calorimetry (DSC) corroborate these findings. Furthermore, SAXS and WAXS demonstrate that the low-temperature state of P4VP−PDP2.0 is not stable and indicate that ultimately macrophase separation into a pure crystalline PDP phase and a microphase separated P4VP−PDP phase occurs.

This paper addresses concentration fluctuations in comblike copolymer systems obtained by hydrogen bonding between polymers and end-functionalized oligomers. Monodisperse block copolymer systems in the homogeneous melt exhibit small-angle X-ray scattering peaks at finite nonzero angle due to characteristic correlation hole concentration fluctuations. In comblike copolymer systems obtained by hydrogen bonding, the dominant fluctuations have been found by us to vary experimentally between conventional long wavelength fluctuations (for weak hydrogen bonding) and finite wavelength fluctuations (strong hydrogen bonding). Monte Carlo computer simulations show that both regimes occur in one and the same system depending on the temperature. The transition between both regimes is directly related to the fraction of free oligomers, which depends on the temperature and the interactions. The structure factors are analyzed in terms of the random phase approximation applied to a mixture of free oligomers and comb copolymers, using a uniform distribution of teeth along the polymer chains and a binomial distribution in the number of polymers with a given number of teeth, confirmed numerically, as input. The agreement is excellent at both high and low temperatures.

Properly selected hydrogen bonding suffices to induce mesomorphic structures in mixtures of flexible polymers and nonmesogenic surfactants. For poly(4-vinylpyridine)−3-pentadecylphenol (P4VP(PDP)x) complexes, the long period of the lamellar structure decreases as x^-1 (x is the number of PDP molecules per P4VP repeat unit) in complete contrast to similar polyelectrolyte systems. Upon cooling from 80 °C to the room temperature, the long period gradually increases and levels off at around 30 °C at a value which is approximately 4 Å above the starting value. After an induction time, a structural transformation occurs in the highly complexed samples, due to the crystallization of the alkyl side chains. It is accompanied by a sudden decrease in the long period of approximately 5 Å. However, the structure is not stable and after an additional induction time both structures are present in the samples. Arguments to explain most of the observed phenomena will be given.

A technique is described for the synthesis of segmented block copolymers of polybutadiene and poly(styrene-co-maleic anhydride) through a polymeric therma iniferter based on polybutadiene, which was used as an initiator for the thermal copolymerization of styrene and maleic anhydride. The polymeric iniferters and block copolymers were characterized by GPC, elemental analysis, 1H NMR, FT-IR spectroscopy, and differential scanning calorimetry. The compositions and SMA block lengths in the block copolymer could be regulated by varying the polymeric iniferter concentration. The maleic anhydride content of the SMA blocks was regulated by adjusting the monomer feed composition. The synthesized block copolymers are very promising materials for use as compatibilizers for nylon-based blends, in particular for blends of nylon with ABS or polyethylene.

A technique is described for the synthesis of poly((styrene-co-acrylonitrile)-block-butadiene-block-(styrene-co-acrylonitrile)) (SAN-PB-SAN) triblock copolymers through polybutadiene-based photoiniferters. Dihydroxy- and dicarboxy-terminated polybutadienes were transformed into the chloro-terminated compounds, which were subsequently reacted with sodium diethyldithiocarbamate into macro-photoiniferters. The dicarboxy-terminated polybutadiene was found to produce unstable dithiocarbamate end groups because of loss of CS2. The dihydroxy-terminated polybutadiene (Mn = 3300 g/mol) was successfully transformed into a macro-photoiniferter, which was used as a photoinitiator for the “living” copolymerization of styrene/acrylonitrile mixtures to obtain the title compounds. By variation of the polymerization time and macroiniferter concentration, the vinyl sequence length and composition of the triblock copolymers could be regulated. The macroiniferters and block copolymers were characterized by GPC, elemental analysis, and ¹H NMR.

The critical interaction strength to induce mesomorphic structures in flexible polymers by complexing with surfactants is determined by using surfactants with different hydrogen-bonding strengths. Two essential requirements have to be satisfied:  (i) the association has to be strong enough, otherwise the structure dissociates. (ii) The polar−nonpolar repulsion has to be sufficiently strong to induce microphase separation. If the latter requirement is not satisfied, but the association is sufficiently strong, a characteristic comb polymer-like SAXS peak will still be present in the homogeneous melt state. To address these issues experimentally, poly(4-vinylpyridine) (P4VP) was combined with different classes of hydrogen-bonding surfactants:  alkyl aromatic alcohols, alkyl carboxylic acids, alkyl aliphatic alcohols, and alkyl aliphatic amines. FTIR, SAXS, WAXS, and optical microscopy demonstrate that alkyl aromatic alcohols, such as 1-dodecyl 3,4,5-trihydroxybenzoate yield mesomorphic structures at not too high a temperature. Alkyl carboxylic acids are somewhat less effective. In the melt state, the SAXS data still show a peak, but because no birefringence could be found, the peak is attributed to block copolymer-like concentration fluctuations in an otherwise homogeneous state. Aliphatic alkyl alcohols yield still weaker hydrogen bonding. In the melt the short alkyl aliphatic alcohol surfactants form a homogeneous mixture with P4VP, but a SAXS peak is no longer observed. The longer ones macrophase separate. Both the alkyl carboxylic acids and the short alkyl aliphatic alcohols partly macrophase separate at lower temperatures due to crystallization.

Symmetric diblock copolymer blends AfB1-f/A1-fBf (0 ≤ f ≤ 0.5) are theoretically discussed in terms of a multiorder parameter approach and numerically investigated by Monte Carlo simulations. Theoretically, our main result is that below f ≅ 0.3, but still in the microphase separation region given by 0.21 ≤ f ≤ 0.5, the concentration profiles of the long and short A-blocks as well as the long and short B-blocks are out of phase. Monte Carlo simulations were used to investigate the nature of the phase transition, micro versus macro, as a function of f. Using the canonical ensemble, the microphase separation temperature (MIST) was determined. The macrophase separation temperature (MAST) was studied with the semi-grand-canonical ensemble combined with the histogram extrapolation technique. The phase diagram differs considerably from the theoretical predictions due to the stretching/polarization of the molecules already far above the transition temperature, thus stabilizing the macroscopically homogeneous state. The out-of-phase behavior between the long and short blocks near the critical value f ≅ 0.21, separating the micro- and macrophase separation regimes, was confirmed by the simulations.

We present a theory for nonlinear dynamics of confined polymer melts under oscillatory flow. Using a Rouse-like model of chains with finite extensibility, we calculate elastic and dissipative stresses and corresponding storage and loss moduli. The effect of bridges and surface slip are taken into account. Several features have been discovered:  the storage modulus G‘ passes through a maximum with increasing strain amplitude in the range of intermediate frequencies, when adsorption is weak and surface slip is important; the elastic σ‘ and dissipative σ‘‘ stresses and the corresponding moduli G‘ and G‘‘ show a jump with increasing strain amplitude when polymer bridges between the surfaces are formed.

A Monte Carlo study is presented to discuss the influence of the side-chain topology on the enhancement of the persistence length of a molecular bottle-brush in a dilute athermal solution due to the excluded volume interactions between the side chains. The structures investigated consisted of freely jointed backbones of 100 hard spheres (beads) of diameter 1 to which 50 equally flexible side chains were grafted. The diameter of the side-chain beads was varied from 1 to 3 in the same units. For every given size of the side-chain bead, the length of the side chains was varied from 4 to 20 beads. The ratio between the persistence length and the bottle-brush diameter, which is the determining factor for lyotropic behavior of conventional semi-flexible chains, was found to be almost independent of the side-chain length. At the same time, it was found to increase considerably with increasing size of the side-chain beads, suggesting that by a proper choice of the chemistry lyotropic behavior of molecular bottle-brushes due to excluded-volume interactions between the side chains might be achieved. Moreover, relatively short side chains can be used since the side-chain length has only a minor influence on the ratio between the persistence length and the diameter. These findings are in a good agreement with recent experimental observations.

We report here on the extension to elastomers of the idea of inducing nanoscale ordering in supramolecular polymer systems based on the principle of hydrogen bonding between amphiphiles and (block co-)polymers. Three different networks have been synthesized using 4-vinylpyridine and divinylbenzene (0.5, 1.0, and 2.0 mol %, respectively) and are further complexed with pentadecylphenol or nonadecylphenol. For low degrees of cross-linking (0.5 and 1.0 mol % divinylbenzene), mesomorphic structures are formed, and order−disorder transitions are observed by small-angle X-ray scattering (SAXS) and differential scanning calorimetry. For the highest degree of cross-linking (2.0 mol % divinylbenzene), mesomorphic structures is no longer observed. The presence of ordered lamellar structures is confirmed by transmission electron microscopy (TEM). SAXS and TEM clearly reveal the deteriorating effect of an increasing degree of cross-linking on the structure formation.

Comb copolymer-like systems obtained by hydrogen bonding between flexible polymers and nonmesogenic amphiphiles represent a class of supramolecular materials with interesting self-organizing properties. Here we present the first results of transmission electron microscopy applied to mesomorphic systems of poly(4-vinyl pyridine)−4-nonadecylphenol as a characteristic example. Phase contrast imaging of iodine-stained samples confirms the highly ordered lamellar structures with a long period of around 40 Å inferred also from small-angle X-ray scattering data.

The phase behavior of mixtures of flexible homopolymer chains with oligomers capable of hydrogen bonding with the monomer units of the polymer chains is analyzed in the weak segregation limit. A theoretical model is proposed to describe hydrogen bond (hb) formation depending on temperature, composition, and strength of hydrogen bonding. The conditions for macro- and microphase separation are studied. Microphase separation takes place if the tendency to segregate is not very strong and the degree of association X is large enough. The type of ordered structure depends not only on the composition and the temperature but also on the possibility to minimize the polymer−oligomer contacts. The period of the ordered structures D is minimal for stoichiometric composition of the mixture and increases with an increase of either component. Macrophase separation into ordered and homogeneous phases is typical for these kind of systems. The corresponding regions of phase coexistence occupy a significant part of the phase diagrams. Coexistence between different ordered phases such as lamellar and hexagonal can also take place. It was found that macrophase separation influences hb formation, reducing the average degree of association. The specific temperature dependence of the degree of association can result in the phenomenon of reappearing phases.

Spectra of the generators of time translations (“Liouville operators”) on representation spaces determined by thermodynamic equilibrium states are compared and their nature is investigated.

We present surface force data on three different polystyrene/poly(2-vinylpyridine) block copolymers (PS/P2VP) with a fixed size of the nonadsorbing PS block but widely varying sizes of the adsorbing P2VP block. With respect to the sizes of the two blocks, they range from moderately to highly asymmetric. The equilibrium force profiles are almost overlapping, which means that the variation in layer thickness is very small over a large range of anchor block size. This finding is in disagreement with the predictions of simple scaling models for polymer brushes. However it agrees with findings from neutron reflectivity data on a comparable series of PS/P2VP block copolymers. We also find agreement with recent neutron reflectivity experiments on poly(dimethylsiloxane)/polystyrene and with self-consistent field calculations on selectively adsorbed block copolymers.

Nonequilibrium molecular dynamics computer simulations have been used to study nanoscopically confined oligomer films under shear. Beyond the well-known density layering across such films, other structural and dynamical inhomogeneities exist across such films and are discussed here. When these films are subjected to strong shear flows, slip appears at the confining surfaces or inside the pore, depending on the wall interactions. For strong wall affinities interlayer slip develops between the adsorbed layer and the free chains, resulting in a structural discontinuity; a molecular mechanism, involving shear induced conformational changes of the adsorbed chains, is associated with this interlayer slip. Moreover, the resistance to flow (quantified through an effective viscosity) changes considerably across the film, with a dramatic viscosity increase of the adsorbed layer near attractive surfaces. Shear thinning is mainly taking place inside this more viscous interfacial layer, whereas the dynamics in the middle of the film remain bulklike; thus, there also exists strong inhomogeneity in the dynamics of the system. A comparison with SFA experimental and theoretical studies is also made.