Synthesis of Polyesters Containing Long Aliphatic Methylene Units by ADMET Polymerization and Synthesis of ABA-Triblock Copolymers by One-Pot End Modification and Subsequent Living Ring-Opening Polymerization.

The synthesis of high-molecular-weight (Mn up to 62,000 g/mol) polyesters has been achieved by acyclic diene metathesis (ADMET) polymerization of α,ω-dienes prepared from biobased bis(undec-10-enoate) and diols [ethylene glycol (M1), propylene glycol (M2), 1,9-nonanediol (M3), 1,4-benzenedimethanol (M4), and hydroquinone (M5)] using ruthenium-carbene catalysts. Replacement of the solvent during the ADMET polymerization was effective for obtainment of the high-molecular-weight polymers (expressed as P1-P5). The melting temperatures (Tm) in the resultant polyesters were dependent upon the diol (middle) segment employed, and the polymer prepared from M5 exceeded 100 °C (a Tm value of 122.5 °C). The polymerization of M3 and M4 in the presence of 1,4-cis-diacetoxy-2-butene (DAB, as the chain transfer agent) afforded the telechelic polyesters [P3(OAc)2 and P4(OAc)2, respectively] containing acetoxy end groups exclusively. The resultant polymers containing hydroxy group termini [P3(OH)2 and P4(OH)2], prepared by the selective deprotection of the acetoxy end groups, were treated with AlEt3 followed by addition of ε-caprolactone to afford the ABA-type triblock copolymers exclusively, through a living ring-opening polymerization. The depolymerization (hydrolysis) under basic conditions (NaOH aqueous solution) of P3 was explored.

Synthesis of Network Biobased Aliphatic Polyesters Exhibiting Better Tensile Properties than the Linear Polymers by ADMET Polymerization in the Presence of Glycerol Tris(undec-10-enoate).

Development of biobased aliphatic polyesters with better mechanical (tensile) properties in film has attracted considerable attention. This report presents the synthesis of soluble network biobased aliphatic polyesters by acyclic diene metathesis (ADMET) polymerization of bis(undec-10-enyl)isosorbide diester [M1, dianhydro-D-glucityl bis(undec-10-enoate)] in the presence of a tri-arm crosslinker [CL, glycerol tris(undec-10-enoate)] using a ruthenium-carbene catalyst, and subsequent olefin hydrogenation using RhCl(PPh3)3. The resultant polymers, after hydrogenation (expressed as HCP1) and prepared in the presence of 1.0 mol% CL, showed better tensile properties than the linear polymer (HP1) with similar molecular weight [tensile strength (elongation at break): 20.8 MPa (282%) in HP1 vs. 35.4 MPa (572%) in HCP1]. It turned out that the polymer films prepared by the addition of CL during the polymerization (expressed as a 2-step approach) showed better tensile properties. The resultant polymer film also shows better tensile properties than the conventional polyolefins such as linear high density polyethylene, polypropylene, and low density polyethylene.

Evaluation of Mitigation Role of L-Phenylalanine-Based Low-Molecular-Weight Gelator against Oil Pollution-Induced Nile Tilapia Toxicity.

A lot of oil is leaked into aquatic environments, significantly impacting fish health and, consequently, human populations. This study aimed to introduce an L-phenylalanine-based low-molecular-weight gelator (expressed as Z-Phe-C18) as a smart remediation tool for oil spills. Several groups of Nile tilapia were allocated in aquaria exposed to different doses of crude engine oil with/without the organogelator for 4 weeks. The results revealed a significant increase in biochemical oxygen demand, chemical oxygen demand, electrical conductivity, and total dissolved solids in water samples of fish aquaria exposed to oil pollution. The antioxidant activity levels, micronucleus formation, and expression patterns of stress-related genes were significantly higher in the livers of fish exposed to crude oil than in those of control fish. On the contrary, fish groups exposed to oil pollution and treated with the organogelator indicated that antioxidant enzymes, micronucleus incidence, and gene expression alteration of stress-related genes declined compared with those exposed to oil pollution only. The results suggest that oil pollution can induce oxidative stress via the enhancement of oxygen free radical formation. On the contrary, oil removal by the organogelator decreases oxidative stress and consequently strengthens fish immunity. So, we can conclude that organogelator treatment is promoting oxidative resistance development by increasing the activities of antioxidant enzymes, which are important in protection against oil pollution and preventing peroxidation of fish tissues. Promisingly, the organogelator could be used as a tool for the remediation of oil pollution in aquatic environments.

Synthesis of High Molecular Weight Biobased Aliphatic Polyesters Exhibiting Tensile Properties Beyond Polyethylene.

Synthesis of high molecular weight polyesters prepared by acyclic diene metathesis (ADMET) polymerization of bis(undec-10-enoate) with isosorbide (M1), isomannide (M2), and 1,3-propanediol (M3) and the subsequent hydrogenation have been achieved by using a molybdenum-alkylidene catalyst. The resultant polymers (P1) prepared by the ADMET polymerization of M1 (in toluene at 25 °C) possessed high Mn values (Mn = 44400-49400 g/mol), and no significant differences in the Mn values and the PDI (Mw/Mn) values were observed in the samples after the hydrogenation. Both the tensile strength and the elongation at break in the hydrogenated polymers from M1 (HP1) increased upon increasing the molar mass, and the sample with an Mn value of 48200 exhibited better tensile properties (tensile strength of 39.7 MPa, elongation at break of 436%) than conventional polyethylene, polypropylene, as well as polyester containing C18 alkyl chains. The tensile properties were affected by the diol segment employed, whereas HP2 showed a similar property to HP1.

Synthesis of Biobased Long-Chain Polyesters by Acyclic Diene Metathesis Polymerization and Tandem Hydrogenation and Depolymerization with Ethylene.

Acyclic diene metathesis (ADMET) polymerization of biobased α,ω-dienes of bis(undec-10-enoate) with diols (1,4-butanediol, isosorbide, isomannide, and 1,4-cyclohexanedimethanol) afforded high-molecular weight unsaturated polyesters, and subsequent tandem hydrogenation (H2 1.0 MPa, 50 °C, 3 h) gave the saturated polymers upon addition of a small amount of Al2O3 (1.0-1.7 wt %). Subsequent reaction of the unsaturated polymers with ethylene afforded the oligomers (by depolymerization and degradation).

Precise synthesis of end-functionalized oligo(2,5-dialkoxy-1,4-phenylene vinylene)s with controlled repeat units via combined olefin metathesis and Wittig-type coupling.

The precise synthesis of chemically, analytically pure oligo(2,5-dialkoxy-1,4-phenylene vinylene)s [OPVs, alkoxy = O(CH2)2OSi(i)Pr3] with strictly controlled repeat units (up to 15 repeat units) and well-defined end groups has been achieved by a combined olefin metathesis reaction of 2,5-dialkoxy-1,4-divinylbenzene or their derivatives with a molybdenum-alkylidene complex and the subsequent Wittig-type cleavage with their dicarboxaldehyde analogues. The effects of the repeat units and the end functional groups toward their UV-vis and the fluorescence spectra have been clearly demonstrated.

Precise Synthesis of Amphiphilic Multiblock Copolymers by Combination of Acyclic Diene Metathesis (ADMET) Polymerization with Atom Transfer Radical Polymerization (ATRP) and Click Chemistry.

Various block (graft) copolymers have been prepared by combination of acyclic diene metathesis (ADMET) polymerization of 9,9-dialkyl-2,7-divinyl-fluorene with Cu-catalyzed atom transfer radical polymerization (ATRP) of styrene using macroinitiators prepared by introduction of initiating functionalities into poly(9,9-dialkylfluorene-2,7-vinylene)s (PFVs) chain ends: a precise synthesis of the amphiphilic ABCBA-type block copolymers has also been attained by subsequent combination with click reaction after modification of the chain end with NaN3.