4-(4-Ethyl­phenyl­diazen­yl)phenol

The crystal structure of the title compound, C14H14N2O, determined at 100 K, shows that the mol­ecules are not planar in the solid state, in contrast to other diazene (azobenzene) derivatives. The dihedral angle between the planes of the two aromatic rings is 42.32 (7)°. The mol­ecules are linked by inter­molecular O—H⋯N hydrogen bonds, forming an infinite one-dimensional chain

Environmentally benign synthesis of saturated and unsaturated aliphatic polyesters via enzymatic polymerization of biobased monomers derived from renewable resources

Aliphatic polyesters are of great interest due to their broad potential applications and sustainability. Itaconate-based aliphatic polyesters are even more appealing in biomedical and pharmaceutical fields, as they are renewable functional polymers that can be biodegradable, biocompatible, and photo-curable, and might be bioresorbable. Herein, various biobased saturated aliphatic polyesters and itaconate-based un-saturated aliphatic polyesters are successfully produced via Candida antarctica Lipase B (CALB)-catalyzed polycondensation of (potentially) biobased dimethyl itaconate, 1,4-butanediol and various diacid ethyl esters, using a two-stage method in diphenyl ether. The synthetic aliphatic polyesters reach high (M-w) over bar (weight average molecular weight) values up to 94 kg mol(-1). Studies on the effect of diacid ethyl esters on the enzymatic polymerization reveal that CALB prefers diacid ethyl esters having a chain length of more than 2 (n > 2, n is the number of methylene groups between the two carbonyl groups); and CALB shows the highest specificity for diethyl adipate among the tested diacid ethyl esters (n = 2-10). Moreover, the structure-property relationships are discussed by investigating the chemical structures, crystalline properties and thermal properties of the obtained aliphatic polyesters, as well as, the thermal transitions and mechanical properties of the UV cross-linked unsaturated polyesters

A biocatalytic approach towards sustainable furanic-aliphatic polyesters

An eco-friendly approach towards furanic-aliphatic polyesters as sustainable alternatives to aromatic-aliphatic polyesters is presented. In this approach, biobased dimethyl 2,5-furandicarboxylate (DMFDCA) is polymerized with various (potentially) renewable aliphatic diols via Candida antarctica Lipase B (CALB)-catalyzed polymerization using a two-stage method in diphenyl ether. A series of furanic-aliphatic polyesters and oligoesters is successfully produced via enzymatic polymerization. Some products reach very high (M-w) over bar (weight average molecular weight) values of around 100 000 g mol(-1). Studies on the effect of the diol structure on the enzymatic polymerization indicate that CALB prefers long-chain alkane-alpha,omega-aliphatic linear diols containing more than 3 carbons. We also found that the molecular weights of the obtained furanic-aliphatic polyesters increase steadily with the increase of reaction temperature from 80 to 140 degrees C. MALDI-ToF MS analysis reveals that five polyester species may be present in the final products. They were terminated with the ester/-OH, ester/ester, -OH/-OH, no end groups (cyclic), and ester/aldehyde groups, respectively. Furthermore, the structure-property relationships were studied by comparing the crystalline/thermal properties of a series of relevant furanic-aliphatic polyesters

Enzymatic Polymerization of Furan-2,5-Dicarboxylic Acid-Based Furanic-Aliphatic Polyamides as Sustainable Alternatives to Polyphthalamides

Furan-2,5-dicarboxylic acid (FDCA)-based furanic-aliphatic polyamides can be used as promising sustainable alternatives to polyphthalamides (semiaromatic polyamides) and be applied as high performance materials with great commercial interest. In this study, poly(octamethylene furanamide) (PA8F), an analog to poly(octamethylene terephthalamide) (PA8T), is successfully produced via Novozym 435 (N435)-catalyzed polymerization, using a one-stage method in toluene and a temperature-varied two-stage method in diphenyl ether, respectively. The enzymatic polymerization results in PA8F with high weight-average molecular weight ((M-w) over bar) up to 54000 g/mol. Studies on the one-stage enzymatic polymerization in toluene indicate that the molecular weights of PA8F increase significantly with the concentration of N435; with an optimal reaction temperature of 90 degrees C. The temperature-varied, two-stage enzymatic polymerization in diphenyl ether yields PA8F with higher molecular weights, as compared to the one-stage procedure, at higher reaction temperatures. MALDI-ToF MS analysis suggests that eight end groups are present in the obtained PA8F: ester/amine, ester/ester, amine/amine, acid/amine, ester/acid, acid/acid, ester/amide, and no end groups (cyclic). Compared to PA8T, the obtained PA8F possesses a similar T-g and similar crystal structures, a comparable T-d, but a lower T-m

Enzymatic Synthesis of Biobased Polyesters Using 2,5-Bis(hydroxymethyl)furan as the Building Block

2,5-Bis­(hydroxymethyl)­furan is a highly valuable biobased rigid diol resembling aromatic monomers in polyester synthesis. In this work, it was enzymatically polymerized with various diacid ethyl esters by Candida antarctica Lipase B (CALB) via a three-stage method. A series of novel biobased furan polyesters with number-average molecular weights (<i>M</i>_n) around 2000 g/mol were successfully obtained. The chemical structures and physical properties of 2,5-bis­(hydroxymethyl)­furan-based polyesters were fully characterized. Furthermore, we discussed the effects of the number of the methylene units in the dicarboxylic segments on the physical properties of the furan polyesters