ADMET Polymerization Research Articles

From Vanillin to Concrete Plasticizers: An Innovative Path through ADMET Polymerization

From Vanillin to Concrete Plasticizers: An Innovative Path through ADMET Polymerization

Furandicarboxylate Polyesters: A Comprehensive ADMET Study of a Novel Class of Furan-Based α,ω-Diene Monomers.

The present research article delves into the preparation of a new class of bio-based polyesters from α,ω-diene furandicarboxylate monomers. In particular, it exploits the use of acyclic diene metathesis polymerisation (ADMET) on 2,5-furandicarboxylic acid (FDCA)-derived compounds. First, a library of furan-based α,ω-diene monomers was prepared via acid- or base-catalyzed transesterification of 2,5-furandicarboxylic acid dimethyl ester (FDME) with commercially available alcohols incorporating terminal olefins, i. e., allyl alcohol, but-3-en-1-ol, hex-5-en-1-ol and dec-9-en-1-ol. Then, the novel monomers were subjected to ADMET polymerisation employing different catalysts and reaction conditions. Interestingly, first-generation Grubbs catalyst was found to be the best promoter for ADMET polymerisation. This catalyst allowed the preparation of a new family of bio-based polyesters with molecular weights up to 26.4 kDa, with good thermal stability, and adaptable cis-trans conformations. Results also revealed that the monomer structure had a direct impact on the polymerisation efficiency and the resulting thermal properties. The effect of green bio-based solvents such as Cyrene™, dimethyl isosorbide (DMI) and γ-valerolactone (GVL) on the polymerisation process was also studied. Data collected showed that the solvent concentration influenced both the yield and length of polymers formed. Furthermore, some co-polymerisation experiments were conducted; the successful integration of different monomers in the resulting copolymer was shown to affect the glass transition temperature (Tg) of the resulting materials.

Regio‐regular and cross‐conjugated poly(thienylene vinylene)s through acyclic diene metathesis

AbstractPoly(thienylene vinylene)s (PTV's) are early examples of conjugated polymers but have not been extensively studied when compared with closely analogous polythiophenes. PTV's synthesized through previously reported techniques are similar in structures that contain various alkyl or alkoxy side‐chains that exert limited impact on the polymer electronic properties. Herein, we report the preparation of a series of regio‐regular PTV's (rr‐PTV's) bearing cross‐conjugated side‐chains through ADMET polymerization of a common brominated di(thienylene vinylene) (DTV) monomer followed by PPM reactions on the resulting brominated PTV. These new polymers contain a bulky silyloxy alkyl side‐chain and a functionalized thiophene moiety on every main‐chain thiophene unit, and their regio‐regular placement is confirmed by NMR spectroscopy. The thienyl based side‐groups broaden polymer absorption ranges and at the same time lead to uncommon emission properties that are results of light‐induced charge transfer events between the polymer main‐chains and side‐chains. Removal of the silyl groups on one of these rr‐PTV's led to insoluble materials and x‐ray diffraction experiments on the collected solids displayed distinct scattering peaks that are absent from similarly functionalized regio‐random PTV's reported previously, thus suggesting better crystallinity originated from regio‐regularity.

Regio-regular poly(thienylene vinylene)s (rr-PTVs) through acyclic diene metathesis (ADMET) polymerization and the impact of alkyl side-chains on polymer molecular weight and solubility

Poly(thienylene vinylene) (PTV) is one of the prototypical conjugated polymers (CPs) that has received relatively little attention. The insertion of one small double bond between every pair of adjacent thiophene units in PTV structures potentially allow direct functionalization of the thienyl rings, which can fine-tune polymer electronic properties without significantly impact main-chain planarity. However, synthetic methods leading to such tailor-designed PTVs are scarce. In this paper, we report a new synthetic strategy that produces a series of regio-regular (rr) PTVs bearing bromine atoms and different alkyl side-chains on every thiophene unit. The methodology starts with synthesis of well-defined dimeric monomers that lead to rr-PTVs upon ADMET polymerization. The monomers and polymers are fully characterized by NMR and absorption spectroscopy. We found that linear and slightly branched alkyl chains led to precipitation during the polymerization process and thus low apparent molecular weight due to limited polymer solubility, while long-branched and bulky silyl-alkyl ether chains led to PTVs with greater solubility and higher molecular weights.

Sequence-regulated vinyl polymers via iterative atom transfer radical additions and acyclic diene metathesis polymerization

Iterative ATRAs and ADMET polymerization enabled the synthesis of sequence-regulated vinyl polymers without statistical distribution of monomer compositions and sequences.

Crystallization of precisely halogen-substituted polyethylenes induced by ultra-high molecular weight polyethylene fiber

The precisely halogen-substituted polyethylenes prepared by ADMET polymerization, that is, PE21F, PE21Cl and PE21Br were chosen as substituted polymers model to study the epitaxial crystallization of substituted polymers induced by the UHMWPE fiber. The morphology, structure and melting behavior of the crystals were characterized by SEM, WAXD and DSC, respectively. The results showed that ribbon crystals with molecular chains parallel to the fiber axis formed on the UHMWPE fiber surface, and the size and regularity decreased with the increase of substituent volume. PE21F with a small substituent could be induced to form two-component crystals on the UHMWPE fiber surface. However, when the substituent volume increased to Cl and Br, the order of crystal formed on the fiber surface was relatively low, which could not induce the crystallization of peripheral molecules. The melting temperatures of the crystals formed on fiber were much higher than that of the bulk polymers, which was attributed to more ordered crystal structure and the thicker lamellae induced by the UHMWPE fiber. In addition, we also discussed the influence mechanism of different structural characteristics and chemical composition of fillers on the crystallization behavior of substituted polymers. This study will establish a better understanding of interface-induced crystallization.

ADMET polymerization in affordable, commercially available, high boiling solvents

Acyclic diene metathesis polymerization is a powerful technique for creating polymers with precise placement of functional groups. However, due to the need to use high vacuum or other methods to remove the volatile ethylene byproduct and drive the reaction forward, traditional solvents are not feasible. Here we demonstrate the use of three cheap, commercially available solvents as a medium for ADMET polymerizations: propylene carbonate, diethyl phthalate, and dioctyl phthalate. We have shown that by using these solvents, we can increase the molecular weights of ADMET-synthesized polyethylene by over 450% as compared to the bulk polymerization as well as reduce polymerization times from 72 h down to 24 and polymerize challenging, solid monomers.

Hybrid polymers bearing oligo-l-lysine(carboxybenzyl)s: synthesis and investigations of secondary structure.

Hybrid polymers of peptides resembling (partially) folded protein structures are promising materials in biomedicine, especially in view of folding-interactions between different segments. In this study polymers bearing repetitive peptidic folding elements, composed of N-terminus functionalized bis-ω-ene-functional oligo-l-lysine(carboxybenzyl(Z))s (Lysn) with repeating units (n) of 3, 6, 12, 24 and 30 were successfully synthesized to study their secondary structure introduced by conformational interactions between their chains. The pre-polymers of ADMET, narrowly dispersed Lysns, were obtained by ring opening polymerization (ROP) of N-carboxyanhydride (NCA) initiated with 11-amino-undecene, following N-terminus functionalization with 10-undecenoyl chloride. The resulting Lysns were subsequently polymerized via ADMET polymerization by using Grubbs’ first generation (G1) catalyst in 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) generating the ADMET polymers (A-[Lysn]m) (m = 2–12) with molecular weights ranging from 3 to 28 kDa, displaying polydispersity (Đ) values in the range of 1.5–3.2. After chemical analyses of Lysns and A-[Lysn]ms by 1H-NMR, GPC and MALDI-ToF MS, secondary structural investigations were probed by CD spectroscopy and IR spectroscopy in 2,2,2-trifluoroethanol (TFE). In order to study A-[Lysn]ms with defined molecular weights and low polydispersity values (Đ = 1.03–1.48), the ADMET polymers A-[Lysn=3]m=3 and A-[Lysn=24]m=4 were fractionated by preparative GPC, and subsequently analysed by 1H-NMR, analytical GPC, MALDI-ToF MS and CD spectroscopy. We can demonstrate the influence of chain length of the generated polymers on the formation of secondary structures by comparing Lysns with varying n values to the ADMET-polymers with the help of spectroscopic techniques such as CD and FTIR-spectroscopy in a helicogenic solvent.

Introducing the reversible chemistry of CO2with diols mediated by organic superbases into polycarbonate synthesis

The reversible reaction of CO2with alcohols mediated by organic superbases was firstly developed to be a toolbox for capturing CO2into polymerizable carbonate monomers applicable for thiol–ene click and ADMET polymerization to produce new libraries of polycarbonates.

Facile preparation of polycarbonates from bio-based eugenol and 2-methoxy-4-vinylphenol

Polymerization of α,ω-diene functionalized carbonate monomers prepared from bio-based eugenol and 2-methoxy-4-vinylphenol through thiol–ene click and ADMET polymerizations produced polycarbonates with moderate molecular weight satisfactory thermal properties.

High Melting Precision Sulfone Polyethylenes Synthesized by ADMET Chemistry

A series of aliphatic polysulfones is synthesized via ADMET polymerization in which a sulfone group is located precisely after every 8th, 14th, and 20th carbon. Primary structural characterization is accomplished using 1H NMR, 13C NMR, and IR. Polymer morphology is studied by DSC and X-ray scattering, which reveals layered morphologies comprised of polyethylene crystallites along with sulfone groups arranged in sheets. In contrast to other precision polymers with functional groups synthesized by ADMET, this morphology is found at all spacer lengths. Prior to hydrogenation the sulfone polymers show Tm decreasing with increasing sulfone concentration, a typical phenomenon attributed to the mix of cis and trans configurations producing defects in the crystals. However, following hydrogenation, the melting temperature increases as the sulfone group concentration increased rather than decreased, with the highest Tm being 175 °C. This is an increase of 45 °C relative to linear polyethylene synthesized via ADMET chemistry. The precise location of the sulfone groups, which are not tactic, within these polyethylenes increases crystallinity, promotes secondary bonding and increases Tm.

ADMET polymerization of biobased monomers deriving from syringaresinol

Renewable α,ω-dienes have been prepared from syringaresinol, a naturally occurring bisphenol deriving from sinapyl alcohol, and further studied as monomers in ADMET polymerizations.

Microwave-assisted ADMET polymerization

Microwave-assisted ADMET polymerization is reported on a series of α,ω-diene monomers, both polar and non-polar. Investigations indicate that of the multiple microwave modes possible, constant power is the most advantageous, providing polymers up to M‾w=31,000g/mol. Molecular weight values are nearly triple in comparison with conventional oil bath heating. Polymers are characterized by NMR, GPC, TGA, and DSC. Microwave irradiation provides a highly controllable and energy efficient ADMET polymerization technique.

Synthesis and characterization of precisely-defined ethylene-co-aryl ether polymers via ADMET polymerization

A new family of polyolefins containing various aryl ether units have been designed and synthesized, and their thermal properties were studied. We prepared six acyclic diene monomers di(undec-10-enyloxy)aryl ether by a two-step approach and the corresponding homopolymers and copolymers with 1,9-decadiene by ADMET. Subsequent hydrogenation gave the corresponding ethylene-co-aryl ether polymers. The structures of these polymers were confirmed by 1H NMR, 13C NMR and FT-IR. Additionally, crystallization behaviors and thermal properties were investigated by differential scanning calorimetry (DSC), X-ray diffraction and thermal gravimetric analysis (TGA). The results show that incorporation of these aryl ether units has improved the thermal stability of polymers. And these polymers show a tendency of semicrystallinity to amorphous state with the insertion of more rigid phenyl rings in functional sites of polymers' main chain. Interestingly, DSC analysis reveals that a sequence of melting/crystallization phenomenon occurs in the crystalline saturated homopolymers.

ADMET polymerization of bio-based biphenyl compounds

Bio-based phenols were dimerized and employed as monomers in ADMET polymerization.

Unveiling the hyperbolic thermal behaviour of poly(p-phenylene alkylene)s

A series of poly(p-phenylene alkylene)s with methylene run lengths ranging from 8 to 40 were obtained by ADMET polymerization of symmetrical α,ω-diene monomers and subsequent exhaustive hydrogenation.

Ladder- and bridge-like polynorbornenes with phosphate linkers: facile one-pot synthesis and excellent properties

A novel telechelic double-stranded polymer with two terminal alkenyl groups was prepared through ROMP of the corresponding monomer bearing a phosphate linker, and was then used as a macromonomer in ADMET polymerization to yield a bridge-like polymer.

Renewable polymers derived from ferulic acid and biobased diols via ADMET

Renewable α,ω-diene monomers have been prepared from ferulic acid, biosourced diols (isosorbide and butanediol) and bromo-alkenes using a chemo-enzymatic synthetic pathway then studied as monomers in ADMET polymerization. All monomers and polymers have been thoroughly characterized using NMR, GPC, DSC and TGA. ADMET polymerization was optimized with regard to catalyst loading (Hoveyda–Grubbs II), reaction medium (in mass vs. in solvent), and temperature, which led to polymers with molecular weight up to 25kDa. Thermal analysis of these new poly(ester-alkenamer)s showed excellent thermal stabilities (283–370°C) and tunable Tg depending on the nature of the biobased diol and the chain length of the alkene in the α,ω-diene monomer.

ADMET Polymerization of Amino‐Acid‐Based Diene

1,4‐Di(homo)allyl‐2,5‐diketopiperazines are synthesized and polymerized via ADMET using the Hoveyda–Grubbs 2nd generation catalyst. The but‐3‐enylated diketopiperazine can be converted into unsaturated tertiary polyamide with molar mass of <3000 g mol−1, whereas the allylated diketopiperazine cannot. Double‐bond isomerization occurs regardless of whether or not benzoquinone is present. A polyesteramide with a higher molar mass of ca. 4800 g mol−1 is obtained by the alternating copolymerization (ALTMET) of 1,4‐di(but‐3‐enyl)‐2,5‐diketopiperazine and ethylene glycol diacrylate. A post‐polymerization modification of the poly(ester)amides via radical thiol‐ene chemistry, however, fails. image

Tuning of HOMO energy levels and open circuit voltages in solar cells based on statistical copolymers prepared by ADMET polymerization

A donor–acceptor statistical copolymer series spanning the entire composition window was prepared and studied in organic solar cells.