High Molecular Mass Research Articles

Ubiquitin-like and ubiquitinylated proteins associated with the maternal cell walls of Scenedesmus obliquus 633 as identified by immunochemistry and LC-MS/MS proteomics.

The cell walls of green algae Scenedesmus obliquus are complex, polymeric structures including an inner cellulose layer surrounded by an algaenan-containing trilaminar sheath. The process of autosporulation leads to the formation of sporangial (maternal) cell walls, which are released into the medium after sporangial autolysis. In this study, a fraction of maternal cell wall material (CWM) was isolated from the stationary phase cultures of Scenedesmus obliquus 633 and subjected to immunofluorescence microscopy using polyclonal anti-ubiquitin antibodies. The water-extracted polypeptide fraction from the maternal cell walls was then analyzed using immunoblotting and LC-MS/MS. An immunoanalysis showed the presence of several peptides reactive with polyclonal anti-ubiquitin serum, with apparent molecular masses of c. 12, 70, 120, 200, and > 250kDa. Cell wall-associated peptides were identified on the basis of LC-MS/MS spectra across NCBI databases, including the Scenedesmaceae family (58 records), the Chlorophyceae class (37 records), and Chlamydomonas reinhardtii (18 records) corresponding to the signatures of 95 identified proteins. In particular, three signatures identified ubiquitin and ubiquitin-related proteins. In the maternal cell walls, immunoblotting analysis, immunofluorescence microscopy, and LC-MS/MS proteomics collectively demonstrated the presence of ubiquitin-like epitopes, ubiquitin-specific peptide signatures, and several putative ubiquitin conjugates of a higher molecular mass. These results support the presence of ubiquitin-like proteins in the extramembranous compartment of Scenedesmus obliquus 633 and suggest that protein ubiquitination plays a significant role in the formation and functional integrity of the maternal cell walls in green algae.

Industrial SMB chromatography as an alternative to the conventional refining of raw cane sugar

Simulated moving bed (SMB) chromatography is a well-established and widespread unit operation in the beet sugar industry and has been practiced commercially for more than thirty years. SMB chromatography has proven to be very efficient at removing inorganic ash components and colorants from sugar liquors, particularly those colorants with relatively high molecular masses. Recent optimization of the separation using raw sugar with a color ranging from 2000 IU up to 4000 IU has focused on minimizing the capital and operating costs of a chromatography system to replace the various purification and decolorization steps in conventional raw cane sugar refining. Decolorization levels exceeding 89% have been reliably achieved in the extract fraction from chromatography, along with ash removals ranging from 92% to 97%. As only water is added to purify the sugar, the application of this technology, in combination with modern industrial heat pumps and mechanical vapor recompression, allows for a powerful CO2-neutral process, with all the associated benefits regarding permits and marketability. The potential of this technology includes integration into new refinery projects (either standalone or back-end) by replacing affination, carbonatation and ion exchange decolorization (with raw sugar colors of up to 5000 IU), to expansion of existing refinery sites for slip stream processing of raw sugar syrups or refinery run-off syrups after clarification, and to the introduction of new process steps, such as direct liquid sugar production from cane raw sugar.

Lipophilic derivatives of EGCG as potent α-amylase and α-glucosidase inhibitors ameliorating oxidative stress and inflammation

Uncontrolled hyperglycemia leads to increased oxidative stress, chronic inflammation, and insulin resistance, rendering diabetes management harder to accomplish. To tackle these myriads of challenges, researchers strive to explore innovative multifaceted treatment strategies, including inhibiting carbohydrate hydrolases. Herein, we report alkyl-ether EGCG derivatives as potent α-amylase and α-glucosidase inhibitors that could simultaneously ameliorate oxidative stress and inflammation. 4″-C18 EGCG, the most promising compound, showed multifold improvement in glycaemic management compared to acarbose, with 230-fold greater inhibition (competitive) of α-glucosidase (IC50 0.81 µM) and 3-fold better inhibition of α-amylase (IC50 3.74 µM). All derivatives showed stronger antioxidant activity (IC50 6.16–15.76 µM) than vitamin C, while acarbose showed none. 4″-C18 EGCG also downregulated pro-inflammatory cytokines and showed no significant cytotoxicity up to 50 µM in primary human peripheral blood mononuclear cells (PBMC), non-cancerous cell line, 3T3-L1 and HEK 293. The in silico binding affinity analysis of 4″-C18 EGCG with α-amylase and α-glucosidase was found to exhibit a good extent of interaction as compared to acarbose. In comparison to EGCG, 4″-Cn EGCG derivatives were found to remain stable in the physiological conditions even after 24 h. Together, the reported molecules demonstrated multifaceted antidiabetic potential inhibiting carbohydrate hydrolases, reducing oxidative stress, and inflammation, which are known to aggravate diabetes.

Molecular and biochemical characterization of a plant-like iota-class glutathione S-transferase from the halotolerant cyanobacterium Halothece sp. PCC7418.

This study identifies a unique glutathione S-transferase (GST) in extremophile using genome, phylogeny, bioinformatics, functional characterization, and RNA sequencing analysis. Five putative GSTs (H0647, H0729, H1478, H3557, and H3594) were identified in Halothece sp. PCC7418. Phylogenetic analysis suggested that H0647, H1478, H0729, H3557, and H3594 are distinct GST classes. Of these, H0729 was classified as an iota-class GST, encoding a high molecular mass GST protein with remarkable features. The protein secondary structure of H0729 revealed the presence of a glutaredoxin (Grx) Cys-Pro-Tyr-Cys (C-P-Y-C) motif that overlaps with the N-terminal domain and harbors a topology similar to the thioredoxin (Trx) fold. Interestingly, recombinant H0729 exhibited a high catalytic efficiency for both glutathione (GSH) and 1-chloro-2, 4-dinitrobenzene (CDNB), with catalytic efficiencies that were 155- and 32-fold higher, respectively compared to recombinant H3557. Lastly, the Halothece gene expression profiles suggested that antioxidant and phase II detoxification encoding genes are crucial in response to salt stress. Iota-class GST was identified in cyanobacteria. This GST exhibited a high catalytic efficiency toward xenobiotic substrates. Our findings shed light a diversified evolution of GST in cyanobacteria and provide functional dynamics of the genes encoding the enzymatic antioxidant and detoxification systems under abiotic stresses.

Statistical optimization, kinetic modeling, and techno-economic analysis for the production of high molecular mass dextran using sugarcane industrial waste-molasses

This study focuses on the transformation of industrial wastes to wealth by utilizing treated sugarcane molasses (TCM) to produce dextran. The fermentation conditions for maximum dextran production were initially optimized using central-composite design in shake-flasks. The highest titer of dextran (60.0 ± 2.0 g/L) was obtained with optimized variables of 150 g/L substrate (TCM), 12.8 g/L yeast extract, 39.8 g/L K2HPO4, and 48 h fermentation time. Then, the profiles of dextran production, TCM consumption, and microbial growth were fitted by kinetic models to obtain the following kinetic parameters: 0.35 h−1 maximum specific growth rate (μmax), 0.48 g dextran/g substrate yield coefficient (Yps), 0.07 maintenance coefficient (ms), and 10.73 g product/g cell growth-associated constant (α). For determining the scale-up factors, the fermentation conditions were replicated in a 3 L fermenter at various stirring speeds (50–250 rpm), and a scale-up strategy based on constant P/V was used to predict the power consumption (1.88–285.51 W) for a pilot-scale of 2000 L working volume fermenter at various stirring speeds (10.8–54 rpm). The dextran produced was characterized using gel permeation chromatography to determine the molecular mass variations (3–4000 kDa) with fermentation conditions. The rheological variations of fermentation broth at different stirring speeds were also studied and related to the molecular mass of the dextran produced. Techno-economic analysis for dextran production explored a gross margin of 22.65 %, a return on investment of 16.80 %, and a pay-back time of 5.95 years.

Application of Cyrene solvent for the fabrication of polymethyl methacrylate, polyethyl methacrylate and composite films containing hydroxyapatite and diamonds

AbstractCyrene is a new biodegradable solvent, which represents a green alternative to many traditional toxic solvents for advanced polymers. Therefore, this investigation is motivated by interest in applications of Cyrene for polymer processing. The feasibility of solubilization of polymethyl methacrylate (PMMA) and polyethyl methacrylate (PEMA) in Cyrene is demonstrated. The ability to form relatively concentrated solutions of the high molecular mass polymers is an important factor for the formation of PMMA and PEMA films by a dip coating method. It was found that the polymer coatings provide corrosion protection of stainless steel in 30 g L−1 NaCl solutions. Another important finding is that the use of Cyrene facilitates the fabrication of stable suspensions of hydroxyapatite (HAp), microdiamond, and nanodiamond particles. Therefore, the problems of the dispersant selection for dispersion of chemically inert diamond and development of biocompatible dispersants are avoided using Cyrene. For the fabrication of composite films, HAp nanorods with reduced particle size are obtained using rutin as a chelating capping agent. Composite films containing HAp, microdiamond and nanodiamond in the PMMA or PEMA matrix are obtained. The composite films are promising for biomedical applications. It was found that the film morphology, composition and microstructure are influenced by the solvent–particle–polymer interactions and processing conditions.

Hyaluronidase inhibitor delphinidin inhibits cancer metastasis

Cancer remains a formidable global health challenge, with metastasis being a key contributor to its lethality. Abundant high molecular mass hyaluronic acid, a major non-protein component of extracellular matrix, protects naked mole rats from cancer and reduces cancer incidence in mice. Hyaluronidase plays a critical role in degrading hyaluronic acid and is frequently overexpressed in metastatic cancer. Here we investigated the potential of targeting hyaluronidases to reduce metastasis. A high throughput screen identified delphinidin, a natural plant compound found in fruits and vegetables, as a potent hyaluronidase inhibitor. Delphinidin-mediated inhibition of hyaluronidase activity led to an increase in high molecular weight hyaluronic acid in cell culture and in mouse tissues, and reduced migration and invasion behavior of breast, prostate, and melanoma cancer cells. Moreover, delphinidin treatment suppressed melanoma metastasis in mice. Our study provides a proof of principle that inhibition of hyaluronidase activity suppresses cancer cell migration, invasion and metastasis. Furthermore, we identified a natural compound delphinidin as a potential anticancer therapeutic. Thus, we have identified a path for clinical translation of the cancer resistance mechanism identified in the naked mole rat.

Trans-complementation of the viral movement protein mediates efficient expression of large target genes via a tobacco mosaic virus vector.

The development of plant virus-based expression systems has expanded rapidly owing to their potential applications in gene functional and disease resistance research, and industrial production of pharmaceutical proteins. However, the low yield of certain proteins, especially high-molecular-mass proteins, restricts the production scale. In this study, we observed that the tobacco mosaic virus (TMV)-mediated expression of a foreign protein was correlated with the amount of the movement protein (MP) and developed a TMV-derived pAT-transMP vector system incorporating trans-complementation expression of MP. The system is capable of efficient expression of exogenous proteins, in particular those with a high molecular mass, and enables simultaneous expression of two target molecules. Furthermore, viral expression of competent CRISPR-Cas9 protein and construction of CRISPR-Cas9-mediated gene-editing system in a single pAT-transMP construct was achieved. The results demonstrated a novel role for TMV-MP in enhancing the accumulation of a foreign protein produced from the viral vector or a binary expression system. Further investigation of the mechanism underlying this role will be beneficial for optimization of plant viral vectors with broad applications.

Quality Control of mRNA Vaccines by Synthetic Ribonucleases: Analysis of the Poly-A-Tail.

The effectivity and safety of mRNA vaccines critically depends on the presence of correct 5' caps and poly-A tails. Due to the high molecular mass of full-size mRNAs, however, the direct analysis by mass spectrometry is hardly possible. Here we describe the use of synthetic ribonucleases to cleave off 5' and 3' terminal fragments which can be further analyzed by HPLC or by LC-MS. Compared to existing methods (e. g. RNase H), the new approach uses robust catalysts, is free of sequence limitations, avoids metal ions and combines fast sample preparation with high precision of the cut.

Influence of swelling on the elasticity of polymer networks cross-linked in the melt state: Test of the localization model of rubber elasticity.

The elasticity of polymer networks, formed by cross-linking high molecular mass polymers in the melt state and then swollen by a solvent, involves contributions from both the presence of cross-link network junctions and the interchain interactions associated with the combined effect of excluded volume interactions and topological constraints that become modified when the network is swollen. We test the capacity of the previously developed localization model of rubber elasticity, a mean field "tube model," to describe changes in elasticity observed in classical experimental studies of the mechanical properties of this type of network. In order to obtain a satisfactory comparison to the experiments, it was found to be necessary to account for the independently observed tendency of the network junctions to become localized in the network with appreciable swelling, as well as the interchain interactions emphasized in previous discussions of the localization model.

Heterogeneous electro-Fenton removal of polyacrylamide in aqueous solution over CoFe2O4 catalyst.

Polyacrylamide (PAM) in environmental water has become a major problem in water pollution management due to its high molecular mass, high viscosity and non-absorption by soil. CoFe2O4 with strong magnetic properties was prepared by solvent-thermal synthesis method and used as the catalyst for the removal on PAM in heterogeneous Electro-Fenton (EF) system. It showed that the removal efficiency of PAM by the heterogeneous EF system using CoFe2O4 catalyst was 92.01% at pH 3 after 120 min. Further studies indicated that ·OH was the most significant active species for the removal of PAM, and the contribution of ·O2- and SO4·- for the removal of PAM was less than 15%. The reusability test and XRD, XPS, FTIR analyses proved that the catalyst had good stability. After a repeated use for five times, the catalyst still had a high PAM removal rate and stable structure. The valence distribution and functional groups of the phase components of the catalyst did not change significantly before and after the reaction. The possible mechanism of catalyst activation of H2O2 was deduced by mechanism investigation. The CoFe2O4 is an efficient and promising catalyst for the removal of PAM wastewater.

Source identification of polycyclic aromatic hydrocarbons (PAHs) in soils around crude oil contaminated area in Ohaji/Egbema, Imo State

ABSTRACT This study aims to determine the source of polycyclic aromatic hydrocarbons (PAHs) in the soils surrounding an area in Ohaji/Egbema, Imo State, that has been contaminated by crude oil. Soil samples were collected in the study area using a soil auger at a depth of 0–20 cm at three sampling locations (sample A, sample B, and sample C) in the Mmahu community in Ohaji/Egbema. In each of the sampling locations, twenty sub-samples were collected from twenty sampling points and pooled together to form representative samples for each of the sampling locations. Prior to GC-MS analysis, the composite samples were air-dried, sieved through a 2-mm mesh, and then kept in pet bottles that had been previously cleaned. The GC-MS investigations were carried out using a Shimadzu Model 2010 GC-MS (Shimadzu, Japan) fitted with an HP-5 MS fused silica column. This was used to quantify the 16 USEPA priority PAHs in the studied soils. The sum of the 16 USEPA priority PAHs in the sample locations ranged from 0.0192 mg/kg in the control sample to 10.73 mg/kg in sample A. Compared to high molecular weight PAHs (4–6 rings), the total concentration of low molecular weight PAHs (2–3 rings) was found to be substantially greater. According to the PAH molecular diagnostic ratio, all sampling points had low to high molecular mass ratios >1, which suggests that the origin of the PAH contamination was petrogenic. The petrogenic source of contamination was attributed to oil spillage around the study area. The knowledge of source identification of PAHs in soils helps in the determination of the most appropriate remediation strategy in order to prevent further contamination and minimise the risks to human health and the environment.

Unraveling the Light‐Absorbing Properties of Brown Carbon at a Molecular Level

AbstractBrown carbon (BrC) exhibits a highly complex chemical composition with diverse light‐absorbing properties, which complicates our understanding of its climate impacts. This study examined the impact of molecular characteristics (including molecular mass, unsaturation, oxidation state, and polarity) and heteroatoms on the light‐absorbing properties (absorptivity and wavelength dependence) of BrC from a molecular perspective, based on the ultraviolet‐visible spectra of over 40,000 light‐absorbing substances in aerosol from different sources and ambience. Our findings reveal that the light‐absorptivity of BrC molecules increases with decreasing polarity and O/C ratio, while it rises with higher molecular mass and unsaturation. We developed predictive models for molecular absorptivity based on its double bond equivalent and O/C ratio. In addition, we observed an inverse correlation between absorptivity and wavelength dependence at the molecular level, as determined through mathematical analysis. This molecular‐level understanding provides valuable insights into BrC absorbing mechanisms, facilitating more accurate characterization in atmospheric models.

Proteomic analysis and lethality of the venom of Aegaeobuthus nigrocinctus, a scorpion of medical significance in the Middle East

The scorpion Aegaeobuthus nigrocinctus inhabits areas in Turkey and the Levant region of the Middle East where severe/lethal envenomings have been reported. Previous research indicated its extreme venom lethality to vertebrates and distinct envenomation syndrome. We report on the composition of A. nigrocinctus venom from Lebanese specimens using nESI-MS/MS, MALDI-TOF MS, SDS-PAGE and RP-HPLC. Venom lethality in mice was also assessed (LD50 = 1.05 (0.19–1.91) mg/kg, i.p), confirming A. nigrocinctus venom toxicity from Levantine populations. Forty-seven peaks were resolved using RP-HPLC, 25 of which eluted between 20 and 40 % acetonitrile. In reducing SDS-PAGE, most predominant components were <10 kDa, with minor components at higher molecular masses of 19.6, 26.1, 46.3 and 57.7 kDa. MALDI-TOF venom fingerprinting detected 20 components within the 1,000–12,000 m/z range. Whole venom ‘shotgun’ bottom-up nLC-MS/MS approach, combined with in-gel tryptic digestion of SDS-PAGE bands, identified at least 67 different components belonging to 15 venom families, with ion channel-active components (K+ toxins (23); Na+ toxins (20); Cl− toxins (2)) being predominant. The sequence of a peptide (named α-KTx9.13) ortholog to Leiurus hebraeus putative α-KTx9.3 toxin was fully determined, which exhibited 81–96 % identity to other members of the α-KTx9 subfamily targeting Kv1.x and Ca2+-activated K+ channels. Chlorotoxin-like peptides were also identified. Our study underscores the medical significance of A. nigrocinctus in the region and reveals the potential value of its venom components as lead templates for biomedical applications. Future work should address whether available antivenoms in the Middle East are effective against A. nigrocinctus envenoming in the Levant area.

Occurrence, removal, and risk assessment of polycyclic aromatic hydrocarbons and their derivatives in typical wastewater treatment plants

Wastewater treatment plants (WWTPs) have a certain removal capacity for polycyclic aromatic hydrocarbons (PAHs) and their derivatives, but some of them are discharged with effluent into the environment, which can affect the environment. Therefore, to understand the presence, sources, and potential risks of PAHs and their derivatives in WWTPs. Sixteen PAHs, three chlorinated polycyclic aromatic hydrocarbons (ClPAHs), three oxidized polycyclic aromatic hydrocarbons (OPAHs), and three methylated polycyclic aromatic hydrocarbons (MPAHs) were detected in the influent and effluent water of three WWTPs in China. The average concentrations of their influent ∑PAHs, ∑ClPAHs, ∑OPAHs, and ∑MPAHs ranged from 2682.50 to 2774.53 ng/L, 553.26–906.28 ng/L, 415.40–731.56 ng/L, and 534.04–969.83 ng/L, respectively, and the effluent concentrations ranged from 823.28 to 993.37 ng/L, 269.43–489.94 ng/L, 285.93–463.55 ng/L, and 376.25–512.34 ng/L, respectively. The growth of heat transport and industrial energy consumption in the region has a significant impact on the level of PAHs in WWTPs. According to the calculated removal efficiencies of PAHs and their derivatives in the three WWTPs (A, B, and C), the removal rates of PAHs and their derivatives were 69–72%, 62–71%, and 68–73%, respectively, and for the substituted polycyclic aromatic hydrocarbons (SPAHs), the removal rates were 41–49%, 31–40%, and 33–39%, respectively; moreover, the removal rates of PAHs were greater than those of SPAHs in the WWTPs. The results obtained via the ratio method indicated that the main sources of PAHs in the influent of WWTPs were the combustion of coal and biomass, and petroleum contamination was the secondary source. In risk evaluation, there were 5 compounds for which the risk quotient was considered high ecological risk. During chronic disease evaluation, there were 11 compounds with a risk quotient considered to indicate high risk. PAHs and SPAHs with high relative molecular masses in the effluent of WWTPs pose more serious environmental hazards than their PAHs counterparts.

Converting Bulk Sugars into Functional Fibers: Discovery and Application of a Thermostable β-1,3-Oligoglucan Phosphorylase.

Despite their broad application potential, the widespread use of β-1,3-glucans has been hampered by the high cost and heterogeneity associated with current production methods. To address this challenge, scalable and economically viable processes are needed for the production of β-1,3-glucans with tailorable molecular mass distributions. Glycoside phosphorylases have shown to be promising catalysts for the bottom-up synthesis of β-1,3-(oligo)glucans since they combine strict regioselectivity with a cheap donor substrate (i.e., α-glucose 1-phosphate). However, the need for an expensive priming substrate (e.g., laminaribiose) and the tendency to produce shorter oligosaccharides still form major bottlenecks. Here, we report the discovery and application of a thermostable β-1,3-oligoglucan phosphorylase originating from Anaerolinea thermophila (AtβOGP). This enzyme combines a superior catalytic efficiency toward glucose as a priming substrate, high thermostability, and the ability to synthesize high molecular mass β-1,3-glucans up to DP 75. Coupling of AtβOGP with a thermostable variant of Bifidobacterium adolescentis sucrose phosphorylase enabled the efficient production of tailorable β-1,3-(oligo)glucans from sucrose, with a near-complete conversion of >99 mol %. This cost-efficient process for the conversion of renewable bulk sugar into β-1,3-(oligo)glucans should facilitate the widespread application of these versatile functional fibers across various industries.

Syntheses of high molecular mass polyglycolides via ring‐opening polymerization with simultaneous polycondensation (ROPPOC) by means of tin and zinc catalysts

AbstractGlycolide was polymerized in bulk by means of four different ROPPOC catalysts: tin(II) 2‐ethylhexanoate (SnOct2), dibutyltin bis(pentafluoro‐phenoxide) (BuSnOPF), zinc biscaproate (ZnCap), and zinc bis(pentafluoro‐phenyl sulfide) (ZnSPF). The temperature was varied between 110 and 180°C and the time between 3 h and 7 days. For the few polyglycolides (PGAs) that were soluble extremely high molecular masses were obtained. The MALDI TOF mass spectra had all a low signal‐to‐noise ration and displayed the peaks of cyclic PGAs with a “saw‐tooth pattern” indicating formation of extended‐ring crystallites in the mass range below m/z 2500. The shape of DSC curves varied considerably with catalyst and reaction conditions, whereas the long‐distance values measured by SAXS were small and varied little with the polymerization conditions.

Influence of solvent quality on the swelling and shear modulus of polymer gels chemically cross-linked in solution

The effect of temperature (T) is studied on the swelling of model poly(vinyl acetate) (PVAc) gels in isopropyl alcohol. The theta temperature Θ of these gels, at which the second osmotic virial coefficient A2 vanishes, is close to that of the corresponding high molecular mass polymer solution without cross-links so that solvent quality may be defined in the same way as the corresponding precursor polymer solution. We quantified the swelling and deswelling of PVAc gels relative to their size at the theta temperature, and also determined the effect of T on the shear modulus of these gels. It was found that both swelling and deswelling data could be reduced to a universal scaling equation of the same general form as derived from renormalization group (RG) theory for flexible linear polymer chains in solutions.Graphical abstractVariaton of the volumetric swelling factor as a function of the reduced temperature for PVAc gels swollen in isopropyl alcohol.

Chemical characterization of polysaccharides from Gracilaria gracilis from Bizerte (Tunisia)

Polysaccharides were extracted from Gracilaria gracilis collected from Manzel Jemil Lake in Bizerte Tunisia, with two different solvents (water and NaOH 0.3 M). Different assays were performed on samples (total sugars, neutral sugars, uronic acids, anhydrogalactose, proteins, sulphates, pyruvates), followed by high performance anion-exchange chromatography (HPAEC) to observe the monosaccharide composition, high pressure size exclusion chromatography with multi-angle laser light scattering (HPSEC-MALS) to obtain the molecular mass, Fourier transform infrared spectroscopy (FTIR), and 1D and 2D nuclear magnetic resonance (NMR) to access to structural data. Results have shown that the polysaccharide extracted from Gracilaria gracilis collected from Manzel Jemil Lake in Bizerte Tunisia, is of agar type but with high molecular mass and some original structural features. Hence, the sample was found to contain 9 % of pyruvate groups and is partly sulphated at the C4 of β-d-galactose and methylated on C2 of anhydro-α-l-galactose. The polymer from G. gracilis from Bizerte thus presents a never described structure that could be interesting for further rheological or biological activities applications.

Combining Cyclic Units and Unsaturated Pendant Groups by Propene/1,5-Hexadiene Copolymerization Toward Functional Isotactic Polypropylene.

The precise use of a widely available and inexpensive metallocene catalyst enabled the synthesis of isotactic polypropylene copolymers characterized by the copresence of randomly distributed cyclic units in the backbone and unsaturated pendant units employing 1,5-hexadiene as comonomer. Optimization of the polymerization conditions avoided the cross-linking phenomena that negatively affects the material processing and final properties, resulting in good yields of samples featuring high molecular masses and a precisely controlled microstructure. Such polypropylene-based copolymers exhibit a broad spectrum of properties ranging from thermoplastic to surprising elastomeric behavior, with the additional value of being functionalizable by post-polymerization reactions.