The low percentage of recyclability the polymeric materials obtained by olefin transition metal (TM) polymerization catalysis has increased interest in their substitution with more eco-friendly reliable physical and mechanical properties. Among variety known biodegradable polymers, linear aliphatic polyesters produced ring-opening (ROP) cyclic esters occupy a prominent position. polymer properties are highly dependent on macromolecule microstructure, control stereoselectivity is necessary...

Extensive characterizations, mainly by wide-angle X-ray diffraction (WAXD) and Fourier transform infrared (FTIR) techniques, are reported for co-crystalline (CC) poly(2,6-dimethyl-1,4-phenylene)oxide (PPO) films with many different low-molecular-mass guest molecules. These characterizations also the corresponding nanoporous crystalline (NC) phases, as obtained suitable guest-removal procedures. Two well-separated NC forms, hereafter named α β, removal from two groups of CC forms. β forms can...

A model for stereoselective ring opening polymerization (ROP) of rac-lactide promoted by chiral aluminum systems is reported based on DFT calculations. The mechanism enantiomorphic site control dictated the catalyst shows unusual features, including active reorganization reaction path, which add complexity and need to be taken into account when addressing challenge recognition.

Poly(lactic acid) (PLA) is one of the best candidates as a sustainable plastic material for circular economy, being biodegradable, bio-based, recyclable, and displaying good thermal mechanical properties. The industrial production PLA mainly based on ring opening polymerization (ROP) l-lactide (l-LA) promoted by tin(II) 2-ethylhexanoate [Sn(Oct)2] in continuous solvent-free process operating at temperatures between 180 200 °C, above melting point resulting isotactic polymer. Despite huge...

The mechanism(s) for the formation of syndiotactic PLA by ROP <italic>meso</italic>-LA a chiral-Al-complex are disclosed DFT calculations.

The synthesis of functionalized polyolefins through coordination–insertion polymerization is a highly challenging reaction. ideal catalyst, in addition to showing high productivity, has be able control the copolymer microstructure and, particular, way polar vinyl monomer incorporation. In this contribution, we modified typical Brookhart's catalyst by introducing fourth coordination site palladium hemilabile, potentially bidentate ligand, such as thiophenimine (N–S). obtained cationic Pd(II)...

The mechanism(s) of alternating PLGA synthesis by ring-opening polymerization (S)- and (R)-3-methyl glycolide promoted enantiopure aluminum complexes have been rationalized density functional theory (DFT) calculations. high regioselectivity the (S)-MeG is obtained repetitive ring opening at glycolyl site (R)-catalyst whereas a lower predicted ROP (R)-MeG. behavior two monomers unveiling active fluxionality catalyst, identifying rate-limiting steps that encode preference versus lactyl site,...

Switching the preference in stereocontrolled rac -LA ROP.

The enantioselective ring-opening copolymerization (ROCOP) of cyclohexene oxide (CHO) and carbon dioxide (CO 2 ) to produce isotactic poly(cyclohexene carbonate) ( i PCHC) was systematically investigated using chiral C 1 -symmetric zinc β-diiminate (BDI) catalysts. A...

To address the limitations of poly (lactic acid) (PLA), it was blended with (methyl methacrylate) (PMMA) as a toughening component, using MgO nanoparticles (NPs, 0.075-0.15 wt%) catalyst. SEM pictures confirmed good miscibility blends. Mechanical tests showed slight decrease in elastic modulus and tensile strength for PLA/PMMA125 sample containing 0.125% MgO. Yet, elongation at break rose by over 60% impact increased 400% compared to pure PLA. Also, facilitated shifting glass transition...

New 3-coordinated Zn ROP catalysts afford lactide stereo-block copolymers with variable block lengths and steric structures diblock ε-caprolactone-lactide at room temperature in short reaction times.

The mechanical properties and the structural transformations occurring during deformation of some commercial grades ethylene/1-octene multiblock copolymers (OBCs) obtained from chain shuttling technology are analyzed. samples characterized by a statistical architecture, where soft amorphous blocks with high octene concentration (≈18.9 mol %) alternate hard crystalline low (≈0.5 %). length (BL) number blocks/chain (NB) change to according distribution. selected have molecular mass in range...

Abstract The mechanisms for the formation of N‐substituted hydrazones by coupling alcohols and hydrazine, achieved sequential processes acceptorless dehydrogenation borrowing hydrogen, has been unveiled density functional theory (DFT) calculations. release water molecular hydrogen as subproducts, combined with Mn‐PNN pincer based catalyst describe a green environment. Mechanistically, apart from describing complex system three coupled catalytic pathways, calculations pivotal role two...

Guest molecular features determining the formation of α and β phases poly(2-6-dimethyl-1,4-phenylene) oxide (PPO) are explored by collecting literature data adding many new film preparations, both solution casting guest sorption in amorphous films. Independently considered preparation method, α-form is favored hydrophobic bulky molecules, while hydrophilic small molecules favor β-form. Furthermore, modeling studies indicate that β-form inducer guests establish stronger dispersive...

The stereoselective rac-lactide ring opening polymerization (ROP) promoted by enantiopure Salen catalysts has been studied Density Functional Theory calculations with the aim of understanding role metal atom in both stereoselectivity and activity process. results obtained M = Al, Sc, Y, La were compared to identify steric electronic effects deriving from centre combining a molecular descriptor based on buried volume percentage (%VBur) parameters, including chemical hardness electrophilicity....

Five new Zn(II) complexes bearing pyridylamido ligands with different substituents at the pyridine and amido moieties were synthesized evaluated as catalysts for alternating copolymerization of carbon dioxide cyclohexene oxide. Polymers carbonate linkages ranging between 86 99% a slightly isotactic-enriched structure selectively obtained under variety reaction conditions, including 1 atm CO2 pressure, without any cocatalyst. Some experimental theoretical evidence suggested that initiating...

Mechanism of the ruthenium-catalyzed protodecarbonylation phthalimides into benzamides elucidated by experiments and calculations: various roles bases responsible for control chemoselectivity.

The electrospinning process is an effective technique for creating micro- and nanofibers from synthetic natural polymers, with significant potential biomedical applications drug delivery systems due to their high drug-loading capacity, large surface area, tunable release times. Poly(L-lactic acid) (PLLA) stands out its excellent thermo-mechanical properties, biodegradability, bioabsorbability. Electrospun PLLA nanofibrous structures have been extensively investigated as wound dressings,...

The mechanism for the synthesis of 2,3-bismethylenechromanes obtained by reaction between silylethynyloxyarenes and allylic pivalates catalyzed a palladium complex has been investigated using computational methods rooted in density functional theory. is promoted C–H bond activation consequent cleavage both substrates, followed novel annulation. whole this described together with drawbacks that could block it. main role played allyl rotation, inducing selectivity, lability phosphine ligand...

When norbornadiene is polymerized with TiCl₄/Et₂AlCl catalytic system, a unique 3,5-poly(norbornadiene) obtained. This new polymer able to crystallize notwithstanding the presence of configurational disorder and packing disorder.

The absorption spectra of polymers derived from ortho, meta and para phenylenediamines (o-PDA, m-PDA p-PDA) have been simulated combining periodic density functional theory (DFT) calculations with time-dependent DFT simulations. These latter carried out on finite clusters embedded in a set point charges devised to exactly reproduce the electrostatic potential chains. results are compared those obtained for solvated o-PDA, p-PDA oligomers increasing sizes extracted structures. electronic...

DFT calculations have been performed to compare metathesis of olefin, diene, and arene substrates catalyzed by a 2 nd generation Ru(SIMes)‐based complex. A large screening modified has with the intention explore energetic gaps between acyclically conjugated alkenes arenes in processes. The results are analyzed through effects conjugation vs. aromaticity, as quantified HOMA NICS aromaticity indices, well non‐covalent interactions coplanar rings and/or any ring functional groups nearby.

A novel protocol for the synthesis of complex framework compounds containing a VCP fragment is presented by means UV conversion CP derivatives at r.t., providing high yields target products in an unprecedented atom economical reversible step.