The main development in macromolecular complexation in aqueous media due to hydrogen bonding over the last decade has been a better understanding of the process of complex formation. Meanwhile an ever growing interest has occurred in introducing hydrogen bonding into the polymers which originally lack donor or acceptor groups. For such polymer solutions it has been demonstrated that the transition from separated coils to complex aggregates takes place when the content of introduced interaction sites reaches a certain level. For the blends with controllable hydrogen bonding in the solid state, the relevant experiments have shown that immiscibility-miscibility-complexation transitions occur upon progressive increase in the density of hydrogen bonding.

Interpolymer Complexation and Miscibility Enhancement by Hydrogen Bonding

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 A 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 A. 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.

Mesomorphic Structures in Flexible Polymer−Surfactant Systems Due to Hydrogen Bonding: Poly(4-vinylpyridine)−Pentadecylphenol

A novel cross-linking approach for a carboxylic acid-containing 6FDA-based copolyimide is presented and characterized. This new type of cross-linking renders the polyimide insoluble in typical solv...

Decarboxylation-Induced Cross-Linking of a Polyimide for Enhanced CO2 Plasticization Resistance

Cross-linked membranes for gas separation have been prepared by thermal treatment of carboxylated polymers of intrinsic microporosity (C-PIMs). The optimal cross-linking temperature was investigated and possible cross-linking pathways involving aryl radical-induced thermal decarboxylation are provided, while several other possible mechanisms are ruled out. Carboxylated PIMs are accessible by controlled hydrolysis of the nitrile-containing parent polymer. The resulting cross-linked PIMs were insoluble in typical solvents and were characterized by Fourier transform infrared spectroscopy (FTIR), TGA-MS, TGA-FTIR, and gel content analysis. The decarboxylated PIM (DC-PIM) membranes showed higher selectivities for the O2/N2, CO2/N2, and CO2/CH4 gas pairs, with evidence of suppression of swelling-induced densification under high CO2 pressure.

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Decarboxylation-Induced Cross-Linking of Polymers of Intrinsic Microporosity (PIMs) for Membrane Gas Separation†

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 ...

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Critical interaction strength for surfactant-induced mesomorphic structures in polymer-surfactant systems

This paper reports on the interpolymer complex formation and polymer blends between poly(monomethyl itaconate) (PMMI) and two polymer acceptors poly(N,N-dimethylacrylamide) (PDMA) and poly(ethyloxazoline) (PEOX). We have found that the formation or inhibition of interpolymer complexes for these systems strongly depends upon the solvent medium. The stoichiometry of the complexes prepared from methanol solutions has been calculated from elemental analysis, resulting in a stoichiometry near a 1:1 ratio. Specific interactions of PMMI/PDMA and PMMI/PEOX complexes and blends have been characterized by FTIR. Strong hydrogen bonding for complexes and blends has been found. Finally, a calorimetric and thermogravimetric study of the complexes and blends has been performed in a wide temperature range.

Blends and complexes of poly(monomethyl itaconate) with polybases poly(N,N-dimethylacrylamide) and poly(ethyloxazoline). Association and thermal behavior

Polymer—polymer complexation between poly(monomethyl itaconate) and poly(vinylpyridine)s

The binary polymeric systems formed by some poly(mono-n-alkyl itaconates) and poly(2-vinylpyridine) or poly(4-vinylpyridine) are studied. Depending on the solvent, two different types of material have been synthesized. On the one hand, using methanol as common solvent, we have obained solid polymer-polymer complexes the composition of which is determined by the initial mixing conditions. On the other hand, pyridine avoids the complexation process, allowing to obtain a true solution of both polymers and, therefore, a solid polymer blend of known composition by solvent casting. Yields of the complexation and stoichiometries of the polymer-polymer complexes have been analysed. In this way, a favoured composition in the range from 3 :2 to 1 : 1 for the mole ratio (referring to repeating units) ratio poly(mono-n-alkyl itaconate) : poly(vinylpyridine) was observed depending on the poly-(mono-n-alkyl itaconate used). Differential Scanning Calorimetry and thermogravimetry have been employed to study the thermal behaviour of complexes and blends. Viscometry measurements have been performed to analyse the interactions in solution. One of the aims of this work has been to analyse the effect of the side group of the poly-(mono-n-alkyl itaconate) in the mixing process as well as in the characteristics of the final products. In this way, higher complexation yields have been obtained using poly-(mono-n-alkyl itoconates) with longer n-alkyl side groups due to the additional stabilisation by solvophobic interactions. On the other hand, the poly(mono-n-alkyl itaconates) with longer n-alkyl groups form polymer-polymer complexes with a higher proportion of poly(4-vinylpyridine), presumably due to their slower kinetics of complexation.

Interpolymer association between poly(vinylpyridines) and poly(mono‐n‐alkyl itaconates). Effect of the n‐alkyl substituent

The thermal degradation of the first six members of poly(mono-n-alkyl itaconates) by thermogravimetry (TG), differential scanning calorimetry (DSC), Fourier Transform infrared (FTIR) and FTIR evolved gas analysis (FTIR-EGA) was studied. The degradation mechanism involves cyclic anhydride formation followed by crosslinking due to the linear anhydride formation. In both processes water and/or alcohol evolution was detected. Also, decarboxylation processes take place on all polymers at high temperatures ( > 180°C). A mechanism of the degradation process is proposed.

José L. Velada

Papers

Blends and complexes of poly(monomethyl itaconate) with polybases poly(N,N-dimethylacrylamide) and poly(ethyloxazoline). Association and thermal behavior

Polymer—polymer complexation between poly(monomethyl itaconate) and poly(vinylpyridine)s

Interpolymer association between poly(vinylpyridines) and poly(mono‐n‐alkyl itaconates). Effect of the n‐alkyl substituent

A study of the thermal degradation of poly(mono‐n‐alkyl itaconates)

The kinetics of bulk polymerization of itaconate derivatives