PA Polymer Research Articles

Green synthesis of chitosan–phytic acid polymers and nanoparticles

Herein, we aimed to synthesize and characterize chitosan (CS) and phytic acid (PA, CS–PA) polymers and nanoparticles for preparing materials with dye adsorption and drug delivery properties. Based on changes in the solution pH and the molecular weight and concentration of CS and PA, the CS–PA polymers and nanoparticles were prepared using a simple one-step ionic cross-linking protocol. CS–PA nanospheres formed polymers at high CS and PA concentrations, whereas CS–PA nanoparticles were formed at very low concentrations and under suitable pH conditions. Higher concentrations of the material produced denser polymers with a varied nanosphere size. Nanoparticles with different morphologies and sizes were obtained by changing the experimental conditions. Moreover, the self-aggregation of CS molecules in solution was reduced at low concentrations, allowing the easy formation of nanoparticles with regular morphological characteristics with PA. The nanoparticles exhibited good stability under specific conditions. The materials generated here showed promising application in dye adsorption and drug delivery field. This study provides clues for the construction and application of CS-based materials.

Studying the Fabrication and Characterization of Polymer Composites Reinforced with Waste Eggshell Powder

Polymeric and plastic materials currently have numerous positive impacts due to their unique properties that make them important for various engineering applications. However, sustainability is a vital factor that should be considered, because of environmental issues. Eggshells (ES) are an important way to reduce the impact of nondegradable materials when applied to reinforce different types of polymer matrices, whether natural or synthetic polymers. Therefore, this study is an attempt to explore the potential application of waste eggshell fillers for the first time as a natural reinforcement in polyamide 12 (PA) composites. PA was loaded with three different ratios (3, 5, and 10 wt. %) of eggshell powder. Morphological studies of the PA powder, ES powder, and their composites were carried out by scanning electron microscopy (SEM). Furthermore, differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy were performed to study the thermal and chemical properties of the raw materials and the produced composites. The results indicate ES fillers’ potential usage as a reinforcement material to develop the thermal and chemical properties of the PA polymer matrix composites, thereby reducing costs and minimizing the environmental pollution caused by waste eggshells and petroleum-based polymers.

Microplastic pollution in vulnerable karst environments: case study from the Slovenian classical karst region

Since the start of mass production of plastic materials more than a century ago, the problem of accumulating plastic waste in the environment has reached epic proportions. Recently, the problem of smaller plastic particles (microplastic, MP) in the environment has become a widely studied topic, but the amount and types of MP in karst environments are still poorly known. Thus, the objective of this study was to collect and analyse samples from various karst habitats and to try and determine the scope of pollution in karst springs that are in part used as sources for drinking water. Of the potential pollution sources, we sampled rainwater, two discharges from wastewater treatment plants, and a leachate from a landfill. We conducted polymer analyses of potential MP particles using FTIR-ATR. The results showed that eight samples from the Postojna region (Postojna–Planina Cave System, rainfall sample and surface streams) contain up to 444 MP particles per m3. However, 32 samples taken from the Škocjan–Kačna–Jama 1 v Kanjaducah Cave System contain up to 60,000 MP particles per m3, with the bulk of particles found in the sediment samples from Škocjan Caves – Kačna Cave System. Samples from Postojna region contained mostly PET, PU and PA polymers, with a minor inclusion of polymers of plastic sponge used for cleaning. Samples from Škocjan region contained mostly PP, PET and PE polymers, with some of PA and PU polymers. Sediment samples contained much less MP particles compared to water samples, which indicates fast transport through karst aquifer.

Repairing performances of novel cement mortar modified with graphene oxide and polyacrylate polymer

Abstract Most cementitious repair materials have non-ignorable drawbacks such as low strength, insufficient bonding, and low anti-permeability. Although the bonding and anti-permeability of repair mortars modified by polymer will be substantially improved, the compressive strength and component integrity will be decreased. Hereby six groups of cement mortars modified by varied dosages of Graphene Oxide (GO) and PA copolymer (GOPARMs) were prepared. The flexural strength (f t), compressive strength (f c), f t/f c, bond strength (f b), and chloride ion migration coefficient (λ c) of GOPARMs were systematically studied by axial compressive, three-bending, pull-out, RCM method, along with microstructure analysis. When GO and PA dosages are fixed at 0.03 and 5 wt%, respectively, the f t, f c, f t/f c, f b, and λ c of GOPARMs reach the best comprehensive performances, which are 6.4, 46.5, 0.14, 6.73 MPa, and 1.179 × 10−12 m2/s. Compared with the control mortar, the f t, f c, f t /f c, and f b of GOPARMs are improved by 5.7, 12.3, 7, and 103%, respectively, and the corresponding λ c is dramatically reduced by 40.4%. Scanning electron microscope (SEM) shows that trace of GO can play a template nucleation effect on the hydration products’ morphology and microstructure of GOPARMs. Meanwhile, cured PA polymer can form hydrophobic film and fill the interfacial pores among hydration products, finally superior repairing performances of GOPARMs with optimal mix can be achieved.

Structural, molecular and thermal properties of cardanol based monomers and polymers synthesized via atom transfer radical polymerization (ATRP)

Cardanol, a byproduct of the cashew processing industry, has been widely studied feeedstock for sustainable monomers and polymers. In this article, the Atom Transfer Radical Polymerization (ATRP) of three radically polymerizable monomers, namely, cardanyl acrylate (CA), hydrogenated cardanyl acrylate (PA) and hydrogenated cardanyl methacrylate (PMA), was studied. The monomers as well as the polymers were structurally characterized and studied by differential scanning calorimetry (DSC) to understad their thermal behavior. The PA monomer showed melting (Tm) at 35 °C and crsytallization (Tc) at −3.27 °C. The synthesized polymer shows Tm of 16.5 °C and the Tc increased to 7.2 °C. In PMA monomer, the Tm was observed at 15.21 °C and Tc at −11 °C and the correponding values for the polymer decreasing to 1 °C and −18 °C, respectively. The coressponding transitions of CA monomer and its polymer were broad and less defined. The homopoymerization of CA and PMA yielded good conversions but the PA polymer yield was low under identical conditions, probably due to the higher monomer crystallinity of PA. The effect of different ATRP ligands, viz, pentamethyldiethylenetriamine (PMDETA) and bipyridine (dNbpy), on the conversion, molecular weight and polydispersity was also investigated.

Dynamic reversible adhesives based on crosslinking network via Schiff base and Michael addition.

It is of practical interest to obtain polymers with complex material properties in a simplified synthetic manner for a broader range of practical applications. In this work, we constructed a dynamic reversible adhesive based on branched polyamine (PA) and p-formylphenyl acrylate (FPA) by simultaneously performing Michael addition reaction and Schiff base reaction. Branched polyamines provide a large number of amino groups as reaction sites that can react with both carbon–carbon double bonds and aldehyde groups. This enables the branched polymeric adhesive system to have a large number of Schiff base bonds within it, an important property of Schiff base bonds is that they are dynamically reversible. This allows us to prepare adhesives with hyperbranched crosslinking networks and recycling properties, and we have verified that FPA–PA adhesives do not exhibit significant fatigue after multiple recycling through the gluing-destruction-gluing process. The resulting FPA–PA adhesives produce tough bonding on multi-substrates such as steel, aluminum, glass, PVC, PTFE, birch and moso bamboo, which exhibited by lap shear strength of 2.4 MPa, 1.7 MPa, 1.4 MPa, 1.3 MPa, 0.4 MPa, 1.6 MPa, and 1.8 MPa, respectively. The feasibility of the synthesis idea of simultaneous Michael addition reaction and Schiff base reaction was demonstrated, as well as the excellent performance and great application potential of FPA–PA adhesives to be recyclable on multi-substrates.

Overview of global status of plastic presence in marine vertebrates.

The presence of plastic in the environment is generating impacts on all habitats and has become a major global problem in marine megafauna. Macroplastics can cause entanglement, ingestion and loss of suitable habitats. In addition to entanglement problems, there is evidence that plastics are entering the food web through ingestion by marine organisms, which could ultimately be affecting humans. Much of the available information on the impact of plastic in biota is scattered and disconnected due to the use of different methodologies. Here, we review the variety of approaches and protocols followed to assess macro- and microplastic ingestion in marine vertebrates such as sea turtles, cetaceans and fishes in order to offer a global overview of their current status. The analysis of 112 studies indicates the highest plastic ingestion in organisms collected in the Mediterranean and Northeast Indian Ocean with significant differences among plastic types ingested by different groups of animals, including differences in colour and the type of prevalent polymers. In sea turtles, the most prevalent types of plastics are white plastics (66.60%), fibres (54.54%) and LDPE polymer (39.09%); in cetaceans, white macro- and microplastics (38.31%), fibres (79.95%) and PA polymer (49.60%); and in fishes, transparent plastics (45.97%), fibres (66.71%) and polyester polymer (36.20%). Overall, clear fibre microplastics are likely the most predominant types ingested by marine megafauna around the globe.

Outcome of using olive oils for MWCNT functionalization and the influence of –OH modified MWCNTs on PA and PBT nano-composites

The effective utilization of carbon nanotubes (CNTs) in polymer matrix depends strongly on their ability to homogeneously disperse throughout the matrix without destroying the structural integrity. The tendency of the CNTs to agglomerate within polymer matrix increases due to the van der Waals force of attraction between individual nanotubes. Thus, the uniform dispersion of the CNTs can be achieved by modifying their surface with the attachment of different functional groups, most commonly by refluxing them in acids in a process known as Functionalization. Despite achieving the improvement in the dispersion quality of CNTs after functionalization in acids, it was noted that the nanotubes got damaged due to the strong interaction of acids. The acid attack on the structure of CNTs causes unwanted defects onto the CNT surface. Thus, alternate routes of functionalizing the CNTs are in dire need. Thus, an effort has been made to explore the use different functionalization mediums that are not as harsh as acids but still are able to functionalize the CNTs to an acceptable extent. Keeping this in view, the present work focuses on functionalizing the MWCNTs using two types of olive oils and comparing their effectiveness with that of H2O2 acid as an medium for –OH functionalization of MWCNTs. The functionalized MWCNTs are further reinforced into PA and PBT polymer matrices for property evaluation in comparison with the non-functionalized MWCNT reinforced nano-composites.

Nanoparticle induced limitless spiral of polyacetylene isomers

Helical nanomaterials represent an emerging group of nanostructures because of their multiple functionalities enabled by unique spiral geometry and nanoscale dimensions. This study demonstrates that several trans-transoid polyacetylene (Tt-PA) chains can self-spiral limitlessly over the whole length of polymers to form regular multiple helices under the inducement of water cluster, fullerene ball and metallic nanoparticles (NPs). Multi-helices possess random chirality selection which have equal probability of left-handedness and right-handedness. Energy components, geometric parameters and differences of helices induced by different NPs are analyzed to deeply probe the possible mechanism and the nature of the limitless spiral of the PA polymer. Furthermore, the helical self-assembly of cis-formed cis-transoid (Ct-PA) and trans-cisoid (Tc-PA) isomers is further studied. The spiral ability of Ct-PA is much higher, but Tc-PA is much lower than that of Tt-PA. Remarkably, Tc-PAs are always form five-helix at room temperature.

Preparation of polyamide thin film nanocomposite membranes containing silica nanoparticles via an in-situ polymerization of SiCl4 in organic solution

Thin film nanocomposite (TFN) membranes with improved permeability is important in the energy-efficient reverse osmosis membrane processes. In this paper, we demonstrate a facile method for the formation of polyamide/silica TFN membranes by an in-situ interfacial polymerization of aqueous amine and acid chloride/silicon tetrachloride (SiCl4) solutions. Water permeability is greatly enhanced with minimal loss in NaCl rejection. Polyamide/silica TFN membranes with 0.04% w/v SiCl4 exhibit a pure water permeability up to 9.7 L m−2 h−1 bar−1, which is 2.02 times more than that of the pristine thin film composite (TFC) membranes, while high rejection to NaCl (96.5%) is maintained. TEM tomograms confirm the existence of silica nanoparticles (NPs) in the thin PA film. More permeable voids are created in the cross-section of TFN membranes. Outer voids are buried underneath the PA protuberances and overhanging crumples. Inner voids and silica NPs are both encapsulated by polyamide. Top surfaces become more hydrophilic and negatively charged. With the optimal amount of SiCl4 loading, the formation of non-selective voids around the particles is minimized. Covalent and hydrogen bonds are formed between SiCl4 and PA polymers. These polyamide/silica nanocomposite membranes outperform many other TFN membranes in water permeability and salt rejection.

Stabilization of Silver Nanoparticles with a Dithiocarbamate Ligand and Formation of Nanocomposites by Combination with Polythiophene Derivative Nanoparticles

Spherical morphology for silver nanoparticles (Ag NPs) stabilized with dithiocarbamate (DTC) by reducing silver nitrate with sodium borohydride was obtained, while the addition of sodium citrate and hydrogen peroxide allowed the formation of silver nanotriangles (Ag NTs). Solutions of bright yellow and blue colors characteristic of both morphologies were observed. UV-vis optical analysis of NPs stabilized with DTC showed a plasmonic absorption band at 393 nm characteristic for spherical morphology, while two bands were observed at 332 nm and 762 nm, and a shoulder around 500 nm for the triangular morphology; with these spectra each morphology was confirmed. In these spectra an absorption band between 250 and 260 nm confirms the presence of DTC ligand. The stability of the NPs was achieved using an 8.69 × 10-3 mM solution of 4-(ethylaminodithiocarbamate) methylpyridine di-n-butyltin (IV) through a transmetallation reaction. Silver nanoparticles (Ag NPs) with spherical morphology of average diameter of 12.7 ± 1.2 nm and triangular morphology with 28.9 ± 0.8 nm for each side of the triangles were analyzed by high resolution scanning electron microscopy (HR-SEM). UV-vis spectra also showed the stability of NPs with DTC for more than three months. A copolymer derived of 3-hexylthiophene with (E)-2-(ethyl(4-((4-nitrophenyl) diazenyl) phenyl) amino) ethyl 2-(thiophen-3-yl) acetate (PA) was tested to get polymer NPs by reprecipitation method using THF/water systems. PA Polymer NPs having average diameter of 9.0 ± 1.7 nm were found. By quick and easy procedure, the formation of nanocomposite (NC) of spherical Ag NPs and PA polymer NPs was reached. This NC could be used as imaging agent, electrochemical biosensor, and photonic and optoelectronic device materials.

From Fullerene-Polymer to All-Polymer Solar Cells: The Importance of Molecular Packing, Orientation, and Morphology Control.

All-polymer solar cells (all-PSCs), consisting of conjugated polymers as both electron donor (PD) and acceptor (PA), have recently attracted great attention. Remarkable progress has been achieved during the past few years, with power conversion efficiencies (PCEs) now approaching 8%. In this Account, we first discuss the major advantages of all-PSCs over fullerene-polymer solar cells (fullerene-PSCs): (i) high light absorption and chemical tunability of PA, which affords simultaneous enhancement of both the short-circuit current density (JSC) and the open-circuit voltage (VOC), and (ii) superior long-term stability (in particular, thermal and mechanical stability) of all-PSCs due to entangled long PA chains. In the second part of this Account, we discuss the device operation mechanism of all-PSCs and recognize the major challenges that need to be addressed in optimizing the performance of all-PSCs. The major difference between all-PSCs and fullerene-PSCs originates from the molecular structures and interactions, i.e., the electron transport ability in all-PSCs is significantly affected by the packing geometry of two-dimensional PA chains relative to the electrodes (e.g., face-on or edge-on orientation), whereas spherically shaped fullerene acceptors can facilitate isotropic electron transport properties in fullerene-PSCs. Moreover, the crystalline packing structures of PD and PA at the PD-PA interface greatly affect their free charge carrier generation efficiencies. The design of PA polymers (e.g., main backbone, side chain, and molecular weight) should therefore take account of optimizing three major aspects in all-PSCs: (1) the electron transport ability of PA, (2) the molecular packing structure and orientation of PA, and (3) the blend morphology. First, control of the backbone and side-chain structures, as well as the molecular weight, is critical for generating strong intermolecular assembly of PA and its network, thus enabling high electron transport ability of PA comparable to that of fullerenes. Second, the molecular orientation of anisotropically structured PA should be favorably controlled in order to achieve efficient charge transport as well as charge transfer at the PD-PA interface. For instance, face-to-face stacking between PD and PA at the interface is desired for efficient free charge carrier generation because misoriented chains often cause an additional energy barrier for overcoming the binding energy of the charge transfer state. Third, large-scale phase separation often occurs in all-PSCs because of the significantly reduced entropic contribution by two macromolecular chains of PD and PA that energetically disfavors mixing. In this Account, we review the recent progress toward overcoming each recognized challenge and intend to provide guidelines for the future design of PA. We believe that by optimization of the parameters discussed above the PCE values of all-PSCs will surpass the 10% level in the near future and that all-PSCs are promising candidates for the successful realization of flexible and portable power generators.

Construction of nanoparticles based on amphiphilic PEI–PA polymers for bortezomib and paclitaxel co-delivery

Polymer nanoparticles based on branched polyethyleneimine and palmitic acid conjugates were fabricated for bortezomib and paclitaxel co-delivery.

Electrospun modified silica-polyamide nanocomposite as a novel fiber coating

In the present work, a new solid phase microextraction (SPME) fiber coating based on modified silica-polyamide (PA) nanocomposite was electrospun on a stainless steel wire. Four modified silica-PA nanocomposites together with PA were fabricated by dispersing several typical modified silica nanoparticles in PA polymer solution prior to electrospinning. The surface characteristic of PA nanofibers and modified silica-PA nanocomposites was investigated using scanning electron microscopy (SEM). The homogeneity and the porous surface structure of the modified silica-PA nanocomposites were confirmed by SEM, showing nanofibers diameters lower than 170nm. The applicability of the new fiber coating was examined by headspace SPME of some selected chlorobenzenes (CBs), as model compounds, from aqueous samples. Subsequently, the extracted analytes were transferred into a gas chromatography (GC) by thermal desorption. Influencing parameters on the morphology of nanocomposites such as type of modified silica nanoparticles and the weight ratio of components were optimized. In addition, effects of different parameters influencing the extraction efficiency including extraction temperature, extraction time, ionic strength, desorption temperature, and desorption time were investigated and optimized. Eventually, the developed method was validated by gas chromatography–mass spectrometry (GC–MS). At the optimum conditions, the relative standard deviation values for a double distilled water spiked with the selected CBs at 100ngL−1 were 4–12% (n=3) and the limit of detection for the studied compounds was between 5 and 30ngL−1. The calibration curves of analytes were investigated in the range of 50–1000ngL−1 and correlation coefficients (R2) between 0.9897 and 0.9992 were obtained.

Life Cycle Assessment of multilayer polymer film used on food packaging field

The environmental impact of a multilayer polymer film, Low Density Poly Ethylene/Polyamide system (LDPE/PA), generally used on food packaging field, was estimated using life cycle assessment (LCA). The aim of the work was to understand how to reduce the environmental pressure from plastic packages for its lower recovery and reuse, which can be improved by developing material recovery or other appropriate recycling technology to improve the cyclic materials flows and recycling ratio. LCA is a tool specifically developed for assessing the overall environmental burden of a product, including the system used for manufacturing it and its end-of-life treatment. This work provides a cradle-to-grave LCA study of a food packaging envelope made with a multilayer polymer film, with two different depth of 70 and 90 micron, and a study of the possibility to utilize a 50% of recycled LDPE and PA polymer pellets in order to reduce the environmental impact. A one square meter envelope is used as functional unit.

Periodic density functional theory calculations for 3-dimensional polyacetylene with empirical dispersion terms

We report periodic B3LYP density functional theory calculations for three-dimensional (3D) trans-polyacetylene (t-PA) fibers. Empirical dispersion terms, as proposed by Grimme, are included with an appropriate re-scaling to yield the B3LYP+D* method implemented in CRYSTAL06. The dispersion corrections are critical for obtaining correct unit cell parameters. In our calculations the out-of-phase P2(1)/n structure turns out to be a transition state for the interchain relative translational motion, which lies about 0.35 kcal mol(-1) above the two symmetrically located in-phase P2(1)/a minima. These results provide a possible new explanation for the observed XRD intensities. Our calculations should also be useful for comparison with more costly non-empirical treatments of 3D PA and other pi-conjugated polymers.

Proanthocyanidin Synthesis and Expression of Genes Encoding Leucoanthocyanidin Reductase and Anthocyanidin Reductase in Developing Grape Berries and Grapevine Leaves

Proanthocyanidins (PAs), also called condensed tannins, can protect plants against herbivores and are important quality components of many fruits. Two enzymes, leucoanthocyanidin reductase (LAR) and anthocyanidin reductase (ANR), can produce the flavan-3-ol monomers required for formation of PA polymers. We isolated and functionally characterized genes encoding both enzymes from grapevine (Vitis vinifera L. cv Shiraz). ANR was encoded by a single gene, but we found two highly related genes encoding LAR. We measured PA content and expression of genes encoding ANR, LAR, and leucoanthocyanidin dioxygenase in grape berries during development and in grapevine leaves, which accumulated PA throughout leaf expansion. Grape flowers had high levels of PA, and accumulation continued in skin and seeds from fruit set until the onset of ripening. VvANR was expressed throughout early flower and berry development, with expression increasing after fertilization. It was expressed in berry skin and seeds until the onset of ripening, and in expanding leaves. The genes encoding LAR were expressed in developing fruit, particularly in seeds, but had low expression in leaves. The two LAR genes had different patterns of expression in skin and seeds. During grape ripening, PA levels decreased in both skin and seeds, and expression of genes encoding ANR and LAR were no longer detected. The results indicate that PA accumulation occurs early in grape development and is completed when ripening starts. Both ANR and LAR contribute to PA synthesis in fruit, and the tissue and temporal-specific regulation of the genes encoding ANR and LAR determines PA accumulation and composition during grape berry development.

Evaluation of pH-dependent membrane-disruptive properties of poly(acrylic acid) derived polymers

Anionic pH-sensitive membrane-disruptive polymers have evolved as a new class of bioactive excipients for the cytosolic delivery of therapeutic macromolecules. A large variety of anionic copolymers and analogues of poly(acrylic acid) (PA) was investigated and compared to a cationic PA copolymer. The pH-responsive membrane-disruptive properties were characterized by employing three in vitro models, such as pH dependent shift of pyrene fluorescence, liposome leakage and lysis of red blood cells. The pH-dependent increase of polarity and membrane disruption in the different model systems was in good agreement for all tested PA polymers. The efficacy of polymer-induced membrane disruption was concentration-dependent and significantly affected by the composition of the membrane. The sensitivity of relatively complex membranes of mammalian cells can be ranked between plain diphosphatidylcholine (DPPC) liposomal membranes and the more rigid cholesterol-containing DPPC membranes. Among the various studied PA polymers, medium and low molecular poly(ethacrylic acid) (PEA) and poly(propacrylic acid) (PPA) were identified as displaying significant pH-dependent disruptive activity. Relative to the disruptive cationic PA polymer (PDMAEM) the ranking is PEA<PPA<PDMAEM. The fine tuning of the pH-responsive hydrophilic–hydrophobic balance is likely to be responsible for the superior effect of PEA and PPA compared to other anionic PA polymers. This thorough investigation of a large variety of different anionic PA polymers and the comparison with an efficient, although rather toxic cationic PA polymer provides a good assessment for further therapeutic applications.

Spectroscopic Investigations on the Inhibition Mechanism of Propargyl Alcohol for Iron Corrosion in Hydrochloric Acid at Elevated Temperatures

Abstract The inhibition mechanism of propargyl alcohol (CH≡CCH2OH [PA]) was investigated for iron (Fe) corrosion in 0.5 M hydrochloric acid (HCl) at elevated temperatures using surface-enhanced Raman scattering (SERS), x-ray photoelectron (XPS), and Fourier transform infrared (FTIR) spectroscopies. SERS spectra of PA adsorbed on an Fe-deposited silver (Ag) electrode revealed that species derived from PA have C=C, =C-H, and C-O bonds. A high inhibitor efficiency (I%) of PA for Fe corrosion in 0.5 M HCl at 70°C was attributed mainly to coverage of the surface with a protective film of PA polymer and partly to adsorption of allyl alcohol (CH2=CHCH2OH [AA]) formed by cathodic reduction of PA. Electroinitiated polymerization of PA at the Fe surface was proposed.

Study of bulk chain coupling reactions. III. Reaction between bisoxazolines or bisoxazlines and carboxy‐terminated oligomers

Abstract2,2′‐Bis(2‐oxazoline) and 2,2′‐bis[5,6‐dihydro‐(4H)‐1,3‐oxazine] have been used as chain coupling reagents (CC) and reacted in the bulk with α,ω‐dicarboxy‐poly(2,2′‐oxydiethylene adipate) (PS) or with α,ω‐dicarboxy‐polyamide 12 (PA). The reactions have been followed by viscosimetry, titration of COOH groups and 1H‐ and 13C‐NMR spectroscopy. Either with the PS/CC or PA/CC systems, or with the model system dodecanoic acid (DA)/CC, the reactions were fast, since in most cases 80% conversion was reached after 15 min reaction. The expected DA dimer or high molar mass PA or PS polymers were obtained. No significant side reaction has been detected. The thermal stability of the resulting polymers is higher than that of starting oligomers. Due to the introduction of CC units in the chains, the crystallinity of PA/CC is slower than that of starting PA. © 1995 John Wiley &amp; Sons, Inc.