Varying Chain Length Research Articles

Separation and identification of a complex flurbiprofen-polyethylene glycol mono- and diester mixture via a hyphenated HPLC-DAD-HRMS/SPE NMR system

We report the use of a hyphenated HPLC-DAD(diode array detector)-HRMS/SPE NMR system for the separation and isolation of a complex mixture of esters, containing substances with very similar LC retention times. The literature known mono- and diesters of the drug Flurbiprofen and polyethylene glycol, which form a large number of substances with varying chain lengths, were chosen for this study. We demonstrate the use of this hyphenated system to quickly and effectively isolate sixteen of these highly similar individual esters in an automated fashion, demonstrating its applicability in standard pharmaceutical analysis and quality control of drugs. Both, synthetic solutions of these esters and extracts from Flurbiprofen lozenges were used for this purpose. By the sole use of this system, the individual compounds were isolated and UV, HRMS and 1D and 2D NMR data could be collected, enabling the identification and differentiation of the individual esters.

Effects of Thin Film Morphology of Polymer Hole Transfer Material on Photovoltaic Performance of Perovskite Solar Cells

In the present study, the effects of chain length variation of Poly(3-hexyl) thiophene polymer, which is one of the appropriate alternatives of Spiro-O-MeTAD used as a hole transfer layer (HTL) in perovskite-based solar cells (PSC), on thin-film morphology and device performance were investigated. Furthermore, nanowires of long (UZ) and short-chain (KZ) P3HT were obtained in the solution phase and then comparative photovoltaic performance analyses were carried out by fabricating PSC devices. As a result, it was determined that the morphological changes resulting from the polymer chain length directly affect the charge transfer between the active layer and HTL. KZ-P3HT presented better performance than both standard P3HT (5.99) and UZ-P3HT (2.68) polymers with a power conversion efficiency (PCE) of 7.74%. It was demonstrated that the main reason for this is that the fringed structure, detected by AFM images, increases the contact ratio at the perovskite/HTM interface. In addition, thanks to the morphological improvements in nano-wire studies, it was observed that the photovoltaic performance of the PSC device containing UZ-P3HT increased by 5.51%. Contrary to UZ-P3HT, it was determined that after the conversion of KZ-P3HT to the nanowire, the fringed structure on the surface disappeared and therefore the efficiency decreased to 5.81%.

Synthesis and potential application of acylhydrazone functionalized linear poly(glycidol)s

Acylhydrazone functionalized linear poly(glycidol) (HLPG) polymers were synthesized as novel nonionic surfactants, where acylhydrazone bond was used as convenient connection to conjugate hydrophobic alkyl chains of various lengths. A comprehensive study of their surface property, foamability/foaming stability and biocompatibility allowed us to establish the corresponding structure–activity profile, which indicated that the physical and biological properties of those surfactants were closely related to the length of attached alkyl side chains. In addition, the drug encapsulation/release tests were conducted to further demonstrate the utility of this type of materials. Thus, our study offered as a valuable reference for their potential practical applications.

Modification of nanocellulose films in deep eutectic solvents using vinyl esters

The hydrophilicity of nanocellulose materials mitigates their good mechanical and oxygen barrier properties when exposed to humid conditions. It also limits nanocellulose use in many applications where water is present. This study reveals hydrophobic modification of cellulose nanofiber (CNF) films with vinyl esters of variable alkyl chain length using deep eutectic solvent (DES) of imidazole and triethylmethylammonium chloride as a reaction medium. Additionally, the influence of ultraviolet-ozone (UV/O3) pretreatment on CNF film modification in DES was addressed. The esterification of CNF films in DES was proven to be a simple and fast approach to increase the hydrophobicity of the films (increasing the contact angle from 38° to 107°), requiring only a 15 min reaction time and reaction temperature of 80 °C. Moreover, the modification improved water vapor barrier properties of the films and resulted in improved mechanical properties at wet state, especially with films treated with UV and ozone before modification.

Modulating superabsorbent polymer properties by adjusting the amphiphilicity.

The role of amphiphilicity in polysaccharide-based superabsorbent polymers is paramount in determining material properties. While the performance of freeze-dried polymers is improved by maximizing hydrophilicity, this may not be the case for evaporative-dried polymers. In this study, four diglycidyl ether crosslinkers, with varying chain lengths and amphiphilicities, were used to synthesize a series of evaporative-dried carboxymethyl cellulose-based superabsorbent films. Through structural and physiochemical characterization, the effect of amphiphilicity on swelling and mechanical properties was established. Contrary to freeze-dried polymers, it was found that the addition of hydrophobic moieties by crosslinking with novel poly(propylene glycol) diglycidyl ether crosslinkers increased the swelling performance of evaporative-dried polymers. By adding hydrophobic functional groups, a reduction in inter-chain hydrogen bonding occurs during evaporative-drying, reducing the degree of hornification and decreasing the entropy requirement for water uptake. By optimizing the amphiphilic ratio, a poly(propylene glycol)-carboxymethyl cellulose polymer achieved a swelling capacity of 182 g/g which is competitive with freeze-dried cellulose-based hydrogels. The mechanical properties of these films improved with the addition of the crosslinkers, with glycerol-carboxymethyl cellulose polymers achieving a tensile strength of 39 MPa and a Young’s Modulus of 4.0 GPa, indicating their potential application as low-cost, swellable films.

A fast gas chromatography coupled with electron capture negative ion mass spectrometry in selected ion monitoring mode screening method for short-chain and medium-chain chlorinated paraffins.

Chlorinated paraffins (CPs) are a group of anthropogenic pollutants that consist of complex mixtures of polychlorinated n-alkanes of different chain lengths (~C10 to C30 ). Persistence, bioaccumulation, toxicity, and long-range transport of short-chain chlorinated paraffins (SCCPs, C10 - to C13 -CPs) have prompted their classification as persistent organic pollutants (POPs) by the Stockholm Convention in 2017. Due to the varying chain lengths and chlorination degrees, quantification of SCCPs and medium-chain chlorinated paraffins (MCCPs, C14 - to C17 ) using gas chromatography coupled with electron capture negative ion mass spectrometry in selected ion monitoring mode (GC/ECNI-MS-SIM) is not only challenging but also very time consuming. In particular, up to eight GC runs per sample are required for the comprehensive GC/ECNI-MS-SIM quantification of SCCPs and MCCPs. These efforts are high especially if the samples do not contain CPs above the limit of detection (LOD), subsequently. We developed a semi-quantitative and sensitive method for the examination of SCCPs and MCCPs in one GC run. This GC/ECNI-MS-SIM screening method was based on the recording of Cl- (m/z 35 and 37), Cl2 - (m/z 70 and 72), and HCl2 - (m/z 71 and 73) isotope ions and evaluation of the ratios between them. Correctness of the results of the screening method was verified by analysis of edible oils with and without CPs, CP standards, as well as a technical CP mixture. Polychlorinated biphenyls (PCBs) and other polyhalogenated aromatic compounds, as well as brominated flame retardants, do not form all of the fragment ions analyzed by the screening method. After the screening, only CP-positive samples may need to be measured in detail. Measurement time will already be gained in the case of ~10% samples without CPs.

Surface Engineering Promoted Insulin-Sensitizing Activities of Sub-Nanoscale Vanadate Clusters through Regulated Pharmacokinetics and Bioavailability.

The therapeutic application of vanadium compounds is plagued by their poor bioavailability and potential adverse effects. Herein, 1nm polyoxovanadate (POV) clusters are functionalized with alkyl chains of various lengths and studied for the effect of surface engineering on their preclinical pharmacokinetics and typical insulin-sensitizing activity. The concentrations of surface engineered POVs in plasma, urine, and feces are monitored after a single administration to rats. The POVs exhibit a two-compartment profile of in vivo kinetics, and the surface engineering effect plays an important role in renal clearance of the POVs comparable to small molecules. POVs functionalized with long alkyl chains show much shorter elimination half time t1/2β and higher elimination fractions (50%) within 48h than pristine POVs, suggesting favorable elimination kinetics to mitigate the possible side effects of vanadium. Meanwhile, long alkyl chain modification leads to a 76% increment of oral bioavailability in contrast to unmodified POVs. As suggested by glucose tolerance tests and sub-chronic toxicity tests, the above two factors contribute to the enhanced therapeutic efficacy of POVs while mitigating their adverse effects. The surface engineering protocol provides a feasible approach to the optimization of the bioavailability and pharmacokinetic properties of POVs for promoted insulin-sensitizing activities.

Physical-chemical and toxicological properties of osmolyte-based cationic surfactants and spontaneously formed low-toxic catanionic vesicles out of them

• Synthesis and properties of osmolyte based cationic surfactants. • Spontaneous formation of low toxic catanionic vesicles composed of these osmolyte based cationic surfactants and soaps. • Appearance of facetted vesicles. • High biodegradability of these novel cationic surfactants and the corresponding catanionic vesicles. In the context of efficient drug delivery systems, catanionic vesicles offer several advantages, such as spontaneous formation and long-term stability. However, especially the cationic component of such vesicles is often toxic. Thus, the search for less toxic, biocompatible amphiphiles, while maintaining the desirable aggregation properties is crucial. In this work, we present cytotoxicity towards the human cell line Hela as well as biodegradability data of some cationic surfactants based on the natural osmolytes choline and ectoine. The synthesis, aggregation and solubility behaviour as well as the stability in water of these compounds is discussed. In order to induce the spontaneous formation of vesicles, several of these cationic surfactants are combined with choline carboxylates with varying chain length in different mixing ratios and characterised with cryo-TEM. Further, the cytotoxic effect of such novel catanionics is evaluated as a function of the cationic-anionic ratio and compared to that of classical combinations of sodium dodecylsulfate and dodecyltrimethylammonium bromide.

Enrichment of poly- and perfluoroalkyl substances (PFAS) in the surface microlayer and foam in synthetic and natural waters

Bench-scale experiments were performed to interrogate poly- and perfluoroalkyl substance (PFAS) enrichment in the water surface microlayer (SML). In initial experiments using electrolyte-only solutions, the perfluorooctane sulfonate (PFOS) and perfluorooctane carboxylate (PFOA) enrichment in the SML were reasonably (with a factor of 2) described by the Gibbs adsorption equation coupled with a Freundlich-based interfacial adsorption model. Enrichment in the SML among perfluorinated sulfonates and perfluorinated carboxylates of varying chain lengths was proportional to their surface activity. The PFOS enrichment factor (EF), defined as the PFAS concentration in the SML divided by the concentration in the bulk water, was 18 in a 200 mg/l NaCl solution. The presence of elevated organic carbon levels in synthetic surface waters inhibited PFAS accumulation in the SML, with resulting EF values of approximately 1 for all PFAS. However, in the presence of elevated organic levels coupled with foam, PFAS enrichment in the foam was observed, with a foam EF of 25 measured for PFOS in synthetic surface waters. PFAS EF values measured in several natural surface waters without foam showed little variation among the waters tested, with PFOS EF values ranging between 6 and 10. Together, these results suggest that PFAS accumulation in the SML is largely controlled by PFAS sorption at the air-water interface for the conditions examined in this study, and the presence of foam with natural organics enhances PFAS uptake at the water surface.

Halide-Free Continuous Synthesis of Hydrophobic Ionic Liquids.

Herein, we present a novel approach for the halide-free, continuous-flow preparation of hydrophobic ionic liquids (ILs) relying on the bis(trifluoromethanesulfonyl)imide (bistriflimide, NTf2–) anion. The simple yet fast two-step synthetic route, which involves the formation of different alkyl bistriflimides (R4NTf2), followed by the quaternization with an amine nucleophile, led to the desired ILs in high yields and excellent purities without any byproduct formation. The variable alkyl chain (R4) length and the broad range of the applicable nucleophiles (R1R2R3N) offer considerable flexibility to the synthetic protocol. The quaternization can be performed under solvent-free conditions; moreover, the homogeneous nature of these reactions allows the application of modern continuous-flow technologies. Given these advantages, the methodology can afford not just a fast and efficient alternative for the conventional synthesis of such compounds with reduced waste water production but their negligible halide content might provide a significantly broader application range of the IL products, especially for the field of materials science.

Comb-shaped polyfluorene with variable alkyl chain length for application as anion exchange membranes

To fabricate anion exchange membranes (AEMs) with high ionic conductivity and excellent chemical stability, in this study, we develop a series of comb-shaped polyfluorene copolymers with side chains of different lengths by superacid-catalyzed Friedel-Grafts polycondensation. Direct introduction of comb-shaped alkyl side chains induce obvious micro-phase separation in these AEMs, as confirmed by atomic force microscopy. PHPFP-QA with the longest side chain has the lowest IEC and the highest ionic conductivity (24.3 mS cm−1 at 20 °C) and power density (596 mW cm−2 at 80 °C) because of its loose structure, which causes more water to be absorbed and a greater hydration number (λ). Owing to a stable piperidinium cation and ether-free backbones, these polyfluorene-based AEMs exhibit excellent alkaline stability. The conductivities of PMPFP-QA, PBPFP-QA, and PHPFP-QA decrease by approximately 23%, 21%, and 17% after immersing them in 2 M KOH at 80 °C for 30 days, respectively. Hence, polyfluorene grafting with comb-shaped side chains can be used to design alkaline electrochemical energy conversion and storage devices.

Synergistic effect of low saline ion tuned Sea Water with ionic liquids for enhanced oil recovery from carbonate reservoirs

In recent decades, low salinity water flooding (LSWF) has gained much attention from both the industry and academia due to its effectiveness in oil recovery. Many efforts are still going on to harness the effect of LSWF combined with chemical enhanced oil recovery (CEOR). However, studies identifying Ionic Liquids (ILs) as potential candidates for CEOR with LSWF are not available in the literature. This study aims to evaluate the synergistic effect of ILs with varying chain lengths ([C8mim] [BF4], [C10mim] [BF4], [C12mim][BF4]) with the low saline ion tuned seawater (ITSW) for enhanced oil recovery (EOR) from carbonate reservoirs. A comprehensive analysis viz. stability and compatibility of ILs, IFT, zeta potential, contact angle, and adsorption analysis were performed to establish the mechanisms. Finally, oil recovery potential was quantified by core flooding. ILs showed a better synergistic effect with ITSW than SW. The IFT value was found to be decreasing with increasing chain length and reduction in salinity. ILs with ITSW demonstrated a strong ability to alter the wettability of rock surfaces to less oil-wet conditions. Zeta potential values turned towards the positive side with adding ILs at the oil/brine and rock/brine interfaces. In addition, ILs have shown significantly less adsorption density in ITSW than SW at the simulated reservoir temperature of 90 °C. IL having the longest chain length ([C12mim] [BF4]) showed superior properties compared to other ILs and reported an incremental recovery of 12% of original oil in place (OOIP) with low saline ITSW. The primary mechanisms involved for better performance of [C12mim] [BF4] with ITSW are calcite dissolution, the interplay of potential determining ions, and enhanced ion pair formation.

Mechanistic Approach to Reveal Interaction of Uranyl Ions in Alkyltriphenylphosphonium Bromide-Based Deep Eutectic Solvent.

Speciation is known to control fundamental aspects of metal processing and electrochemical behavior such as solubility and redox potentials. Deep eutectic solvents (DESs) are an emerging class of green, low-cost and designer solvents and are being explored as alternatives for recycling nuclear fuel and critical materials. However, there is a lack of knowledge about the behavior of metals in them. Here, for the first time, we synthesized three new DESs based on alkyltriphenylphosphonium bromide (CnPPh3Br), with varied alkyl chain lengths (n), as the hydrogen-bond acceptor along with decanoic acid (DA) as the hydrogen-bond donor and explored the redox speciation of uranyl nitrate. The changes in the Fourier transform infrared and NMR spectra helped elucidate the formation of hydrogen bonds in DES. The absorption maxima of uranyl in DES was red-shifted by 10 nm compared to the free uranyl, with concomitant increase in intensity and luminescence lifetime, which suggested a strong interaction of uranyl nitrate with DES. Cyclic voltammetry was probed to understand the redox thermodynamics, transport properties, and heterogeneous electron transfer kinetics of the irreversible electron transfer of uranyl ions in the three DESs. Electrochemical and spectroscopic techniques together with density functional theory calculations unlocked microscopic insights into the solvation and speciation of UO22+ ions in three DESs and also the associated unusual trends observed in the physical properties of the DESs. The hydrogen-bonded structure of DES plays a crucial role in the redox behavior of the UO22+ ion due to its strong potent complexation with its components. The basic findings of the present work can have far-reaching consequences for the extraction, electrochemical separation, and future development of redox-based separation processes in the nuclear fuel cycle.

Photoinduced ring-opening olefination of cycloalkanols and access to tunable cycloenones

We have developed a dual-catalytic strategy for the synthesis of linear alpha olefins with variable chain lengths from readily available cycloalkanols. This strategy was realized by combining photocatalyzed ring opening of cycloalkanols and Cu-mediated β-H elimination. The terminal desaturation was achieved at aryl and alkyl ketones’ γ , δ , ε , or more remote sites under mild conditions with remarkable functional group tolerance. The resulting diene products via this approach have the potential to be transformed into challenging tunable medium-sized cycloenones. • Wide functional group tolerance • Readily offer substrates for ring-closing metathesis • Access to tunable enones and cycloenones Alkenes are much preferred building blocks in organic synthesis. They are widely used in developing new reaction patterns and constructing sophisticated molecules. This inspires researchers to develop more alkene synthesis methodology from diverse substrates. Our methodology paved the way to preparation of terminal alkenes from cycloalkanols. Enones and cycloenones were thus achieved with variable chain lengths or ring sizes accordingly. As olefins are important building blocks, this transformation can serve as a powerful tool to enrich the arsenal of organic synthesis. Alcohols areall over the area of organic chemistry and the world. We contributed to the conversion of them into enones with at least one double bond. Enones with two double bonds could be perfectly employed in ring-closing metathesis, affording tunable cycloenones. It is interesting that if these cycloenones were converted into tertiary alcohols, they can be utilized in our methodology again.

Improving the Electrochemical Stability of a Polyester-Polycarbonate Solid Polymer Electrolyte by Zwitterionic Additives.

Rechargeable batteries with solid polymer electrolytes (SPEs), Li-metal anodes, and high-voltage cathodes like LiNixMnyCozO2 (NMC) are promising next-generation high-energy-density storage solutions. However, these types of cells typically experience rapid failure during galvanostatic cycling, visible as an incoherent voltage noise during charging. Herein, two imidazolium-based zwitterions, with varied sulfonate-bearing chain length, are added to a poly(ε-caprolactone-co-trimethylene carbonate):LiTFSI electrolyte as cycling-enhancing additives to study their effect on the electrochemical stability of the electrolyte and the cycling performance of half-cells with NMC cathodes. The oxidative stability is studied with two different voltammetric methods using cells with inert working electrodes: the commonly used cyclic voltammetry and staircase voltammetry. The specific effects of the NMC cathode on the electrolyte stability is moreover investigated with cutoff increase cell cycling (CICC) to study the chemical and electrochemical compatibility between the active material and the SPE. Zwitterionic additives proved to enhance the electrochemical stability of the SPE and to facilitate improved galvanostatic cycling stability in half-cells with NMC by preventing the decomposition of LiTFSI at the polymer–cathode interface, as indicated by X-ray photoelectron spectroscopy (XPS).

Characterization on Lead-Free Hybrid Perovskite [NH3(CH2)5NH3]CuCl4: Thermodynamic Properties and Molecular Dynamics.

It is essential to develop novel zero- and two-dimensional hybrid perovskites to facilitate the development of eco-friendly solar cells. In this study, we investigated the structure and dynamics of [NH3(CH2)5NH3]CuCl4 via various characterization techniques. Nuclear magnetic resonance (NMR) results indicated that the crystallographic environments of 1H in NH3 and 13C on C3, located close to NH3 at both ends of the cation, were changed, indicating a large structural change of CuCl6 connected to N–H···Cl. The thermal properties and structural dynamics of the [NH3(CH2)nNH3] cation in [NH3(CH2)nNH3]CuCl4 (n = 2, 3, 4, and 5) crystals were compared using thermogravimetric analysis (TGA) and NMR results for the methylene chain. The 1H and 13C spin-lattice relaxation times (T1ρ) exhibited similar trends upon the variation of the methylene chain length, with n = 2 exhibiting shorter T1ρ values than n = 3, 4, and 5. The difference in T1ρ values was related to the length of the cation, and the shorter chain length (n = 2) exhibited a shorter T1ρ owing to the one closest to the paramagnetic Cu2+ ions.

Quality-by-design approach for development of aqueous headspace microextraction GC-MS method for targeted metabolomics of small aldehydes in plasma of cardiovascular patients

Lipid peroxidation products, such as short chain aldehydes, are powerful biomarkers of oxidative stress, due to the advantage of long lifetime compared to other metabolites of the lipidome. This work proposes an advanced combined derivatization/solvent-less extraction procedure from plasma followed by rapid Gas Chromatography with Mass Spectrometric detection (GC-MS). A new sample pretreatment protocol is presented which is based on a combination of aldehyde derivatization with methoxyamine under fully aqueous-based conditions of diluted plasma samples followed by headspace solid-phase microextraction (HS-SPME) which is faster compared to methods in the literature serving the same purpose. Being the smallest oximation reagent, methoxyamine derivatization does not require a silylation step of hydroxyl groups as customary and made it possible to have the shortest run times for this series of aldehydes by GC-MS. A Response Surface Methodology (RSM) is employed to optimize the HS-SPME of the aldehyde methoximes to provide insights into the Design Space (DS) of HS-SPME of aldehydes of variable chain lengths and unsaturation. The workflow includes a Quality by Design (QbD) approach for optimization of sample microextraction and derivatization methodology under fully aqueous conditions, in contrast to all reported non-aqueous tedious and long extraction methods in the literature followed by development of a rapid GC-MS assay. The optimal sample preparation obtained from the RSM, and multiple linear regression procedure involved addition of 15 mg methoxyamine (CH3ONH2) and 160 mg Na2SO4 to 0.5 mL plasma diluted to 1 mL with water in an extraction vial followed by HS-SPME using Polydimethylsiloxane/Divinylbenzene fiber at 750 rpm and 77 °C for 15 min. The developed HS-SPME-GC-MS method was validated according to FDA guidelines in SIM mode and applied for targeted determination of lipid peroxidation aldehyde metabolites in plasma of 24 cardiovascular patients vs 20 healthy controls. The run time of the GCMS method was less than 15 min and the LOQ of the 10 targeted aldehydes were 0.5 nM for decanal, 5 nM for hexanal, heptanal, octanal, citronellal and citral, 7 nM for malondialdehyde, 35 nM for 4- hydroxynonenal, 105 nM for 4- hydroxyhexenal and 500 nM for glyoxal. Hexanal, Malondialdehyde and Hydroxynonenal concentrations were significantly higher in patients (p-value<0.05) in the targeted study, while citral was significantly lower as obtained from the untargeted study. Reporting an aldehydic profile signature -whether predictive or diagnostic-for cardiovascular patients would support proper medical intervention at the initiation or progression phases of the disease when expanded on larger number of subjects.

Efficient Dye-Sensitized Solar Cells Based on a New Class of Doubly Concerted Companion Dyes.

To develop efficient dye-sensitized solar cells (DSSCs), concerted companion (CC) dyes XW60-XW63 constructed from the covalent linkage of a strapped porphyrin dye unit and an organic dye unit have been reported to exhibit panchromatic absorption and excellent photovoltaic performance. However, these CC dyes only afforded moderate VOC values of ca. 763 mV, demonstrating relatively weak antiaggregation ability, which remains an obstacle for further enhancing the photovoltaic behavior. To address this problem, we herein develop porphyrin dyes XW77-XW80 with the macrocycles wrapped with alkoxy chains of various lengths (OC6H13-OC22H45) and the corresponding CC dyes XW81-XW84 containing these porphyrin dye units. Interestingly, the new CC dyes XW81-XW83 exhibit increasing VOC from 745 to 784 mV with the chain lengths extended from C6 to C18, and a lowered VOC of 762 mV was obtained for XW84 when the chain length was further extended to C22. As a result, XW83 afforded the highest PCE of 12.2%, which is, to the best of our knowledge, the record efficiency for the iodine electrolyte-based solar cells sensitized with a single dye. These results can be rationalized by the so-called doubly concerted companion (DCC) effects, that is, the two subdye units exhibit not only complementary absorption but also concerted antiaggregation with the long wrapping chains on the porphyrins unit simultaneously protecting the porphyrin macrocycle and the neighboring organic subdye unit, thus affording panchromatic absorption and strong antiaggregation and anticharge-recombination ability. These results provide a new approach for constructing a class of DCC dyes to achieve high-performance DSSCs without using any antiaggregating coadsorbent or absorption-enhancing cosensitizer.

Effect of aliphatic segment length and content on crystallization and biodegradation properties of aliphatic-aromatic co-polyesters

In this work, dimethyl terephthalate (DMT), 1,4-butanediol (BDO) and different diacids were introduced to investigate the effects of variations in aliphatic chain length and component content in aliphatic aromatic terpolymers on the basic thermal properties, crystalline morphology, mechanical properties and biodegradability of the polyesters. The experimental results from nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FT-IR) and Gel permeation chromatography (GPC) indicate the successful synthesis of the anticipated aliphatic aromatic co-polyesters. The variation of melting and crystallization temperatures with aliphatic chain segment length and content were analyzed by differential scanning calorimetry (DSC). The Wide-angle X-ray diffraction (WAXD) results suggest that the coexistence of both crystals formed by rigid and flexible chain segments can be achieved by varying the length and component content of the aliphatic chain segments in the co-polyesters. The scanning electron microscopy (SEM) and composting experiment results indicate that the type of crystals formed with the more flexible chain segments and the lower degree of crystallinity have a positive effect on the biodegradability.

Chain Length Effect on the Structural and Emission Properties of the CuI/Bis((4-methoxyphenyl)thio)alkane Coordination Polymers.

A systematic chain length variation of the ligand para-MeOC6H4S(CH2)mSC6H4OMe (1 ≤ m ≤ 8) was performed to study its effect on the structures and photophysical properties of the coordination polymers (CP) when reacted with CuI. Indeed, direct correlations are noted between these features and m. When m is an odd number, the secondary building unit is systematically the common closed-cubane Cu4I4 cluster, rendering the material strongly luminescent (i.e., emission quantum yield, Φe > 20%), and the CP is one-dimensional (1D). However, when m is 2, 4, and 6, the SBUs exhibit rare polymeric motifs of (Cu2I2)n: staircase ribbon, fused poly(rhombic pseudo-dodecahedron), and accordion ribbon, respectively, and the emission intensities are either very weak (Φe < 0.001%) or of medium intensity (Φe ∼ 10% when m = 6). When m = 8 (i.e. the most flexible chain), the SBU is a closed-cubane Cu4I4 and the emission intensity is medium (Φe ∼ 10%). A special case was observed for m = 3, where a co-crystallization of the molecular cluster Cu4I4(NCCH3)4 is observed in the lattice, which turns out to be quite important for the stability of the network.