Melt Condensation Polymerization Research Articles

Poly(ester‐anhydrides) with controlled molecular weight and structure

AbstractWe report on the synthesis of a series of poly(ester‐anhydride) composed of the following dicarboxylic acids: adipic, suberic, sebacic, dodecanedioic acids; and hydroxyalkanoic acids: ricinoleic and 12‐hydroxystearic acid with control molecular weight approaching from a new method in which well‐defined ester monomers are first synthesized by stepwise addition of hydroxyalkanoic acids molecules into melted dicarboxylic acids. The key advantage of the synthesis of ester monomers in this modified method is the full consumption of hydroxy acid devoid of any self‐condensation. The ester monomers are then activated using variable amounts of acetic anhydride followed by melt condensation polymerization. The molecular weights of the synthesized poly(ester‐anhydride) are highly controllable depending upon the degree of activation of the ester monomers; hence the amount of acetic anhydride. All the synthesized poly(ester‐anhydrides) are thoroughly characterized by 1H NMR, Fourier transform infrared, and gel permeation chromatography.

Self-healing polyurethane coatings of eugenol-based polyol incorporated with linseed oil encapsulated cardanol-formaldehyde microcapsules: A sustainable approach

The development of eco-friendly materials is a major challenge tackled by preparing polymers of renewable origin as an alternative to the petroleum sources and by reducing repairing cost via formulating self-healing materials. In this study, cardanol and eugenol are used as renewable-phenols for the formulation of microcapsule based self-healing anticorrosive coatings. Cardanol was used to prepare microcapsules through an oil-in-water (O/W) emulsion system, whereas eugenol was utilized for the synthesis of polyester polyol by solvent-less melt condensation polymerization. The structure of polyol was confirmed by FTIR and NMR spectroscopies, while formation and surface morphology of microcapsules was confirmed by the FE-SEM. The thermal stability of microcapsules stood up to 232 °C as tested by TGA. The prepared microcapsules were dispersed in polyol formulations and crosslinked with methylene diphenyl diisocyanate to obtain self-healing smart PU coatings. The self-healing property of the prepared coatings was observed under FE-SEM. The developed coatings showed good physico-chemical properties such as gloss, crosscut adhesion, flexibility, pencil hardness, and MEK rub test. The corrosion resistance of the formulated self-healing coatings was found to be increased with increase in the quantity of microcapsules as studied by immersion and electrochemical methods.

Novel Biobased Polyamide Thermoplastic Elastomer with Medium Hardness

AbstractThermoplastic elastomers (TPEs) are useful in various engineering and healthcare applications. A new fully biobased polyamide TPE (PA36,9) with medium hardness is reported. The elastomer is synthesized using a fatty dimer amine and azelaic acid, via one‐pot melt condensation polymerization. The resulting elastomer shows a melting temperature of 83.6 °C, a medium hardness (Shore A/Shore D = 90/35), a large elongation at break (1220%), good resilience, and impact resistance, while maintaining high tensile strength (31.8 MPa), low density (0.93 g cm−3), and hydrophobicity. The chemical structure of the repeating unit, together with the molecular weight and molecular weight distribution, of the polymer governs the properties of the resulting polyamide, which differ from those of conventional aliphatic polyamides. This biobased polyamide elastomer is a promising candidate to substitute some fossil fuel‐based medium‐hardness TPEs for applications, such as insulation, sealing, automotives, and construction.

Malleable and Sustainable Poly(ester amide) Networks Synthesized via Melt Condensation Polymerization

Polymers synthesized directly from plant oils such as castor oil usually exhibit poor mechanical properties and cannot be reprocessed due to the soft, highly cross-linked and permanent cross-linkin...

Poly (l-lactic acid) synthesis using continuous microwave irradiation–simultaneous cooling method

In this study, Poly(l-lactic acid) (PLLA) synthesis was studied using direct melt condensation polymerization (DMP) method in an experimental microwave (MW) system where external cooling was applied to keep both temperature (T) and MW power (P) continuous and constant during the polymerization. T, P, reaction time (t), catalyst type, and catalyst amount were considered to determine appropriate process conditions. In addition, some experiments were carried out under the similar process conditions using MW-assisted ring opening polymerization (MW-ROP) and conventional heating (CH) methods. These methods were compared in terms of process performance and various properties of the oligomeric PLLA. According to results, polymerization rate, polymer yield, average-molecular weight, the dispersity, and thermal properties of PLLA products were similar in both MW methods but higher than CH counterparts. Furthermore, low crystallinity of PLLA products synthesized by MW methods showed the effect of MW on the optical purity (L or D) of products. Finally, energy saving was accomplished by 73% and an increase of polymer production rate by 37.7% in MW-DMP method.

Synthesis, characterizations and application of bisphenol-A based highly branched polyol in polyurethanes coatings

In present work, bisphenol-A based polyol was synthesized by melt condensation polymerization with 2, 2-Bis (hydroxymethyl) propionic acid. FTIR, NMR were used for structural characterization of polyol. Also TGA and DSC were used for the thermal properties determinations. The polyurethanes were obtained using reactions between polyol and isophorone diisocynate in various OH: NCO molar ratios which were applied on mild steel panels and glass plates coating purpose. The coating properties of polyurethanes were determined by gloss, cross cut adhesion, corrosion by emersion test in HCl, NaCl, NaOH and Water.

Pinosylvin-Based Polymers: Biodegradable Poly(Anhydride-Esters) for Extended Release of Antibacterial Pinosylvin.

Pinosylvin is a natural stilbenoid known to exhibit antibacterial bioactivity against foodborne bacteria. In this work, pinosylvin is chemically incorporated into a poly(anhydride-ester) (PAE) backbone via melt-condensation polymerization, and characterized with respect to its physicochemical and thermal properties. In vitro release studies demonstrate that pinosylvin-based PAEs hydrolytically degrade over 40 d to release pinosylvin. Pseudo-first order kinetic experiments on model compounds, butyric anhydride and 3-butylstilbene ester, indicate that the anhydride linkages hydrolyze first, followed by the ester bonds to ultimately release pinosylvin. An antibacterial assay shows that the released pinosylvin exhibit bioactivity, while in vitro cytocompatibility studies demonstrate that the polymer is noncytotoxic toward fibroblasts. These preliminary findings suggest that the pinosylvin-based PAEs can serve as food preservatives in food packaging materials by safely providing antibacterial bioactivity over extended time periods.

Biodegradable polyester films from renewable aleuritic acid: surface modifications induced by melt-polycondensation in air

Good water barrier properties and biocompatibility of long-chain biopolyesters like cutin and suberin have inspired the design of synthetic mimetic materials. Most of these biopolymers are made from esterified mid-chain functionalized ω-long chain hydroxyacids. Aleuritic (9,10,16-trihydroxypalmitic) acid is such a polyhydroxylated fatty acid and is also the major constituent of natural lac resin, a relatively abundant and renewable resource. Insoluble and thermostable films have been prepared from aleuritic acid by melt-condensation polymerization in air without catalysts, an easy and attractive procedure for large scale production. Intended to be used as a protective coating, the barrier's performance is expected to be conditioned by physical and chemical modifications induced by oxygen on the air-exposed side. Hence, the chemical composition, texture, mechanical behavior, hydrophobicity, chemical resistance and biodegradation of the film surface have been studied by attenuated total reflection–Fourier transform infrared spectroscopy (ATR–FTIR), atomic force microscopy (AFM), nanoindentation and water contact angle (WCA). It has been demonstrated that the occurrence of side oxidation reactions conditions the surface physical and chemical properties of these polyhydroxyester films. Additionally, the addition of palmitic acid to reduce the presence of hydrophilic free hydroxyl groups was found to have a strong influence on these parameters.

Isothermal Crystallizaiton Kinetic and Melting Behaviors of Nylon 6/66/510

In this work, nylon 6/66 (S0) and nylon 6/66/510 (S1~S3) containing 5 ~ 15 mol % nylon-510 were synthesized by melt condensation polymerization and the isothermal crystallization kinetics and melting behaviors after isothermal crystallization of copolymer were systematically studied by differential scanning calorimetry (DSC). The chemical structures and molecular weights were characterized by means of nuclear magnetic resonance ( 1 H-NMR). The values of t 1/2 and the equilibrium melting temperature for all samples were calculated by Avrami equation and HoffmanWeeks, respectively. The crystal structure of the copolyamides were also investigated by wide-angle X-ray diffraction (WARD). The results shows that: (1) Avrami model can be used to well describe the isothermal crystallization behavior of the copolyamides, and all the values of t 1/2 increase with increasing the Tc or the mole fraction of nylon 510. (2) The crystallization activation energy ( ∆E) and nucleation constant ( Kg) both increase with increasing the mole fraction of nylon-510, which indicating that the addition of nylon nylon-510 decreases the crystallization rate of copolymer.

Toughening modification of PLLA by combination of copolymerization and in situ reactive blending

PLLA/PLLA-b-PBAT-b-PLLA/(PLLA-b-PGMA)3 blends with different ratio.

Polyhydroxyester Films Obtained by Non-Catalyzed Melt-Polycondensation of Natural Occurring Fatty Polyhydroxyacids

Free-standing polyesters films from mono and polyhydroxylated fatty acids (C16 and C18) have been obtained by non-catalyzed melt-condensation polymerization in air at 150°C. Chemical characterization by Fourier Transform Infrared Spectroscopy (FTIR) and 13C Magic Angle Spinning Nuclear Magnetic Resonance (13C MAS-NMR) has confirmed the formation of the corresponding esters and the occurrence of hydroxyl partial oxidation which extent depends on the type of hydroxylation of the monomer (primary or secondary). Generally, polyester films obtained are hydrophobic, insoluble in common solvents, amorphous and infusible as revealed by X-ray Diffraction (XRD) and Differential Scanning Calorimetry (DSC). In -polyhydroxy acids, esterification reaction with primary hydroxyls is preferential and, therefore, the structure can be defined as linear with variable branching depending on the amount of esterified secondary hydroxyls. The occurrence side oxidative reactions like the diol cleavage are responsible for chain cross-linking. Films are thermally stable up to 200-250°C though this limit can be extended up to 300°C in the absence of ester bonds involving secondary hydroxyls. By analogy with natural occurring fatty polyesters (i.e. cutin in higher plants) these polymers are proposed as biodegradable and non-toxic barrier films or coatings to be used, for instance, in food packing

Novel alkyd-type coating resins produced using cationic polymerization

Novel, partially bio-based poly(vinyl ether) copolymers derived from soybean oil and cyclohexyl vinyl ether (CHVE) were produced by cationic polymerization and investigated for application as alkyd-type surface coatings. Three different polymers were produced and cured clear coatings and free films characterized as a function of CHVE comonomer content and curing conditions. CHVE comonomer content was varied at 0, 25, and 50 wt%, and the three different curing conditions were 1 week at room temperature, 120°C for 1 h, and 150°C for 1 h. The results of the study showed that the thermal, mechanical, and physical properties of the coatings produced from these novel polymers varied considerably as a function of polymer composition and cure temperature. Overall, the results suggest a good potential for these novel copolymers to be used for coatings cured by autoxidation. Compared to conventional alkyd resins, which are produced by high temperature melt condensation polymerization, these poly(vinyl ether)s provide several advantages. These advantages include milder, more energy efficient polymer synthesis, elimination of issues associated with gelation during polymer synthesis, production of polymers with well-defined composition and relatively narrow molecular weight distribution, and elimination of film formation and physical property issues associated with entrained monomers, dimers, trimers, etc.

Long-Chain Polyhydroxyesters from Natural Occurring Aleuritic Acid as Potential Material for Food Packaging

Fatty polyhydroxyesters (C≥16) are present in nature as barrier polymers like cutin in some protective tissues of higher plants. The mimicry of these biopolymers is regarded as a strategy to design nontoxic and fully biodegradable food packaging films and coatings. To obtain cutin inspired materials we have used a natural occurring polyhydroxylated monomer like aleuritic (9,10,16-trihydroxypalmitic) acid and a direct and scalable synthesis route consisting in the noncatalyzed melt-condensation polymerization in air. To reduce the number of hydroxyl groups and to increase hydrophobicity, palmitic acid has been used as a capping agent. Aleuritic-palmitic polyhydroxyesteres films have been obtained and characterized.

Bio-based poly(vinyl ether)s and their application as alkyd-type surface coatings

Novel bio-based poly(vinyl ether) copolymers derived from soybean oil and menthol were produced by cationic polymerization and investigated for application as alkyd-type surface coatings. Compared to conventional alkyd resins, which are produced by high temperature melt condensation polymerization, the bio-based poly(vinyl ether)s were thought to provide several advantages. These advantages include milder, more energy efficient polymer synthesis, elimination of issues associated with gelation during polymer synthesis, production of polymers with well-defined composition and relatively narrow molecular weight distribution, and elimination of film formation and physical property issues associated with entrained monomers, dimers, trimers, etc. As expected, incorporation of the tri-substituted cycloaliphatic groups derived from menthol pendent to the poly(vinyl ether) polymer backbone significantly increased the glass transition temperature and mechanical properties of crosslinked networks produced by autoxidation. Overall, the results of the study suggest a high potential for these novel copolymers with high bio-based content to be used for alkyd-type coatings.

Donor–Acceptor Random Copolyesters containing Perylenebisimide (PBI) and Oligo(p-phenylene vinylene) (OPV) by Melt Condensation Polymerization: Energy Transfer Studies

Novel copolyesters consisting of oligo(p-phenylene vinylene) (OPV) as donor (D) and perylenebisimide (PBI) as acceptor (A) were synthesized by melt polycondensation. Photoinduced energy transfer and photoinduced charge separation in these polyesters were studied in solution as well as in the solid state. Selective excitation of OPV moiety resulted in the energy transfer with >90% efficiency from OPV to PBI chromophore in the solution state. The direct excitation of PBI in the D-A copolyester resulted in reduced fluorescence emission of acceptor, indicating electron transfer between the D and A moieties. The effect of distance between donor and acceptor on the energy transfer efficiency from donor to acceptor was studied. Compared to a physical mixture of D and A polyesters alone, the energy transfer was 4 times more efficient in the D-A copolyester, highlighting the influence of covalently linking D and A in a single polymer chain. A strong fluorescence quenching (∼ 100%) of both chromophores in solid state indicated an efficient photoinduced charge transfer after photoexcitation of either D or A. Thus, OPV-PBI main chain copolyester is an excellent system for the study of energy- and electron-transfer processes in organic semiconductor. Reactive blend of D/A copolyester was also prepared by the transesterification reaction between D and A alone copolyesters. The energy transfer efficiency from D to A moiety upon selective excitation of D chromophore in the D/A copolyester blend was ∼4 times higher compared to a physical mixture of D and A alone copolyesters, which gave direct proof for the transesterification reaction in polyester/polyester reactive blending.

Synthesis and Characterization of a New Kind of Flame-Retardant Thermotropic Liquid Crystal Containing 1,8-octanediamine Softsegment

Using the diacetate of 10-(2,5-dihydroxyphenyl)-10-hydrogen-9-oxa-10-phosphorin-10-oxide, p-acetoxy-benzoic acid, terephthalic acid and the condensation product of terephthalic acid and 1,8-octanediamine as monomers, a new kind of flame-retardant thermotropic liquid crystal copolyester containing phosphorus, nitrogen and 1,8-octanediamine softsegment (PN-TLCP) was synthesized by melt condensation polymerization. The structure and properties of PN-TLCP, such as molecular structure, texture of liquid crystal and thermal properties were investigated by fourier transform infrared spectra, X-ray diffraction, hot-stage polarizing optical microscope, differential scanning caborimetry and thermal gravimetric analysis. The results showed that the texture of PN-TLCP was the type of nematic liquid crystalline within the bounds of 180∼330°C, and its melting point was 148°C. It was proved that there were P-O and P=O stretching vibration absorption bands and C-N and C=N mixed absorption bands in Fourier transform infrared spectra of PN-TLCP. Also, the thermal stability and the char yield of PN-TLCP are favorable.

Structure, tensile properties and cytotoxicity assessment of sebacic acid based biodegradable polyesters with ricinoleic acid.

A new family of ricinoleic acid based polyesters was synthesized using catalyst free melt-condensation polymerization with sebacic acid, citric acid, mannitol and ricinoleic acid as precursors. The use of FT-IR and NMR characterisation techniques confirms the presence of ester linkages in the as-synthesized polymers. Depending on the precursor combination, their relative amount and the degree of curing, a broad range of elastic modulus (22-327 MPa) and tensile strength (0.7-12.7 MPa) can be obtained in the newly synthesized biopolymers. The polymers show rubbery behaviour at a physiological temperature (37 °C) and the contact angles of the synthesized polymers fall in the range of 42° to 71°, making them ideal substrates to study delivery of drugs through polymer scaffolds. The cytocompatibility assessment of the cured polymers confirmed good cell attachment and growth of smooth muscle cells (C2C12 myoblast cells). Importantly, oriented cell growth was observed after culturing myoblast cells for 3 days. The in vitro degradation in PBS indicates that the mild cured polymers follow a first order reaction kinetics and have degradation rate constants in the range of 0.009-0.038 h-1, depending on the relative proportions of monomers. Overall, the results of our study indicate that the physical properties can be tailored by varying the composition of the monomers and curing conditions in the newly developed polyesters. Hence, they may be used as potential substrates for tissue engineering scaffolds and for localized drug delivery.

PolyMorphine: An innovative biodegradable polymer drug for extended pain relief

Morphine, a potent narcotic analgesic used for the treatment of acute and chronic pain, was chemically incorporated into a poly(anhydride-ester) backbone. The polymer termed “PolyMorphine”, was designed to degrade hydrolytically releasing morphine in a controlled manner to ultimately provide analgesia for an extended time period. PolyMorphine was synthesized via melt-condensation polymerization and its structure was characterized using proton and carbon nuclear magnetic resonance spectroscopies, and infrared spectroscopy. The weight-average molecular weight and the thermal properties were determined. The hydrolytic degradation pathway of the polymer was determined by in vitro studies, showing that free morphine is released. In vitro cytocompatibility studies demonstrated that PolyMorphine is non-cytotoxic towards fibroblasts. In vivo studies using mice showed that PolyMorphine provides analgesia for 3days, 20 times the analgesic window of free morphine. The animals retained full responsiveness to morphine after being subjected to an acute morphine challenge.

Syntheses and Evaluation of Copolymer 6-Aminohexanoic Acid and 4R-Hydroxy-L-Proline for Bone Repair

A novel synthetic copolymer (PAA) for bone repair was prepared by melt condensation polymerization with 6-aminohexanoic acid (He) and 4R-hydroxy-L-proline (Hyp). The structure and thermal property were characterized by infrared spectrometer (IR), nuclear magnetic resonance (H1NMR) and differential scanning calorimeter (DSC). The results indicated that the PAA had amide linkages in their polymer chains. The Tg of PAA was 57.56°C and significantly higher than that of nylon6, 50.46°C. Meanwhile, the intrinsic viscosity and mechanical properties were investigated at different He/Hyp ratios. It revealed that appropriate introduction of Hyp group could control the degree of polycondensation and adjusted mechanical properties of PAA obviously close to natural bone. The prepared polymers had about 2.12~18.21 % weight loss after 8-week soaking in PBS, showed degradable properties which was essentials to new bone growth. The copolymer of He and Hyp with ratios of 90/10 had 6.57 % weight loss and maintained the yield compressive strengths with about 67.51 MPa after 8 weeks, which exhibited a compatible mechanical properties and degradation speed for bone repair.

Copolymerization of glycolic, d,l-lactic and d,l-2-hydroxybutyric acid mixtures present in kraft black liquors

A series of copolymers of glycolic acid (GA), d,l-lactic acid (dl-LA) and d,l-2-hydroxybutyric acid (dl-2HBA) were prepared via melt condensation polymerization. The utilized monomers represent mixtures that are present and potentially obtainable from kraft black liquor by fractionation. Polymerizations were performed in 165°C at nitrogen atmosphere and reduced pressure using stannous octoate as catalyst. Copolymerizations were conducted with varying dl-2HBA content in order to observe how the presence of the dl-2HBA monomer affects the properties of the polymers. Prepared copolymers were characterized with 1H NMR and 13C NMR, size exclusion chromatography, differential scanning calorimetry and thermogravimetric analysis. The obtained copolymers had molecular weights between Mw=3500–10,000g/mol. dl-2HBA had a lowering effect on the glass transition temperatures and molecular weights of the copolymers. However, significant lowering of molecular weight was observed only when the amount of dl-2HBA in the feed exceeded 60%. The results indicate that dl-2HBA can be copolymerized with GA and dl-LA and therefore the corresponding kraft black liquor fractions can be utilized for polymerizations.