Simple bifunctional salts for synthesising block copolymers from anhydrides/epoxides and vinyl acetate.

Herein, we report the first synthesis of poly(ester--vinyl acetate) epoxide/anhydride ring-opening copolymerisation and reversible addition-fragmentation chain transfer polymerisation. This was achieved using simple, robust and bifunctional alkali metal carboxylates featuring a xanthate unit.

Ring-opening polymerization of ε-caprolactone with a macrocyclic tetracarbene indium complex.

The first chiral tetracarbene indium(III) complexes have been synthesized by employing a rigid dianionic macrocyclic tetra-NHC ligand. The macrocyclic indium tetra-NHC bromide and ethoxide complexes are structurally similar to analagous salen complexes. The indium ethoxide complex effectively promotes living ring-opening polymerization of ε-caprolactone at room temperature.

Simple divalent metal salts as robust and efficient initiators for the ring-opening polymerisation of -lactide.

Simple divalent metal benzoxides are reported as robust and efficient catalysts for lactide (LA) polymerisation. Following a "pre-stir" step to aid solubility, the best performing catalyst, Zn(OBn), gave quantitative monomer conversion in just 30 seconds and performed well under industrially relevant settings with high monomer loadings, bulk polymerisation conditions and non-anhydrous conditions using technical grade LA.

Unlocking the Potential of Polythioesters.

As the demand for sustainable polymers increases, most research efforts have focused on polyesters, which can be bioderived and biodegradable. Yet analogous polythioesters, where one of the oxygen atoms has been replaced by a sulfur atom, remain a relatively untapped source of potential. The incorporation of sulfur allows the polymer to exhibit a wide range of favorable properties, such as thermal resistance, degradability, and high refractive index.

Cooperative heterometallic catalysts: balancing activity and control in PCL--PLA copolymer synthesis.

Heterometallic cooperativity is gaining momentum in cyclic ester ring-opening polymerisation, yet remains surprisingly underexplored in their block copolymerisations. Here, we report the first homogeneous heterometallic "ate" catalysts for poly(ε-caprolactone)-poly(lactic acid) block copolymers, showcasing the substantial differences in the polymer structures observed upon exchanging Zn for Mg or Ca.

Exploiting Multimetallic Cooperativity in the Ring-Opening Polymerization of Cyclic Esters and Ethers.

The use of multimetallic complexes is a rapidly advancing route to enhance catalyst performance in the ring-opening polymerization of cyclic esters and ethers. Multimetallic catalysts often outperform their monometallic analogues in terms of reactivity and/or polymerization control, and these improvements are typically attributed to "multimetallic cooperativity". Yet the origins of multimetallic cooperativity often remain unclear.

NacNac-zinc-pyridonate mediated ε-caprolactone ROP.

Herein we report the synthesis, isolation and polymerisation activity of two new zinc compounds based on a 2,6-diisopropylphenyl (Dipp) β-diiminate (NacNac) ligand framework with zinc also ligated by an amidate (2-pyridonate or 6-methyl-2-pyridonate) unit. The compounds crystallised as either monomeric (6-Me-2-pyridonate derivative) or dimeric (2-pyridonate) species, although both were found to be monomeric in solution H DOSY NMR spectroscopy, which was supported by DFT calculations. These observations suggest that both complexes initiate ring-opening polymerisation (ROP) through a single-site monometallic mechanism.

Correction: Main group metal polymerisation catalysts.

Correction for 'Main group metal polymerisation catalysts' by Eszter Fazekas , , 2022, , 8793-8814, https://doi.org/10.1039/D2CS00048B.

Main group metal polymerisation catalysts.

With sustainability at the forefront of current polymerisation research, the typically earth-abundant, inexpensive and low-toxicity main group metals are attractive candidates for catalysis. Main group metals have been exploited in a broad range of polymerisations, ranging from classical alkene polymerisation to the synthesis of new bio-derived and degradable polyesters and polycarbonates ring-opening polymerisation and ring-opening copolymerisation. This tutorial review highlights efficient polymerisation catalysts based on Group 1, Group 2, Zn and Group 13 metals.

Low Formaldehyde Binders for Mineral Wool Insulation: A Review.

Insulating materials are ubiquitous in a built environment and play a critical role in reducing the energy consumed to maintain habitable indoor environments. Mineral wool insulation (MWI) products, including glass, stone, and slag variants, are the most widely used class of insulating materials in Europe and account for more than 50% of the total market by volume. MWI typically consists of two key components: a mesh of inorganic fibers that are several micrometers in diameter, and an organic thermosetting adhesive commonly referred to as the "binder.

Salt additives as activity boosters: a simple strategy to access heterometallic cooperativity in lactide polymerisation.

Inorganic salt additives can activate carbonyl groups towards organic addition reactions. Here, we translate this concept to ring-opening polymerisation for the first time, generating heterometallic ProPhenol catalysts , which show similar activity enhancements to pre-formed heterometallic complexes. Extremely high activities are observed, with K/Mg and K/Ca combinations converting >85 eq.

Combining alkali metals and zinc to harness heterometallic cooperativity in cyclic ester ring-opening polymerisation.

Heterometallic cooperativity is an emerging strategy to elevate polymerisation catalyst performance. Here, we report the first heterotrimetallic Na/Zn and K/Zn complexes supported by a ProPhenol ligand, which deliver "best of both" in cyclic ester ring-opening polymerisation, combining the outstanding activity (Na/K) and good control (Zn) of homometallic analogues. Detailed NMR studies and density-functional theory calculations suggest that the Na/Zn and K/Zn complexes retain their heterometallic structures in the solution-state.

Advances in heterometallic ring-opening (co)polymerisation catalysis.

Truly sustainable plastics require renewable feedstocks coupled with efficient production and end-of-life degradation/recycling processes. Some of the most useful degradable materials are aliphatic polyesters, polycarbonates and polyamides, which are often prepared via ring-opening (co)polymerisation (RO(CO)P) using an organometallic catalyst. While there has been extensive research into ligand development, heterometallic cooperativity offers an equally promising yet underexplored strategy to improve catalyst performance, as heterometallic catalysts often exhibit significant activity and selectivity enhancements compared to their homometallic counterparts.

Cooperative Heterometallic Catalysts for Lactide Ring-Opening Polymerization: Combining Aluminum with Divalent Metals.

While homometallic (salen)Al catalysts display excellent performance in lactide ring-opening polymerization (ROP), heterometallic (salen)Al complexes have yet to be reported. Herein, we describe four heterobimetallic (salen)Al catalysts and show that the choice of the heterometal is key. Cooperative Al/Mg and Al/Zn combinations improved the catalyst activity by a factor of up to 11 compared to the mono-Al analogue, whereas the mono-Mg and mono-Zn analogues were completely inactive.

Iron Half Salen Catalysts for Atom Transfer Radical and Ring-Opening Polymerizations.

A series of monometallic pentacoordinate Fe chloride complexes have been prepared and characterized by high-resolution mass spectrometry and elemental analysis. X-ray diffraction analysis showed that the bis-chelated Fe complexes bear distorted trigonal bipyramidal geometries. The air- and moisture-stable Fe complexes were screened as mediators in the reverse atom transfer radical polymerization (ATRP) of styrene and methyl methacrylate.

Erratum: Heterodinuclear zinc and magnesium catalysts for epoxide/CO ring opening copolymerizations.

[This corrects the article DOI: 10.1039/C9SC00385A.].

Heterodinuclear zinc and magnesium catalysts for epoxide/CO ring opening copolymerizations.

The ring-opening copolymerization of carbon dioxide and epoxides is a useful means to make aliphatic polycarbonates and to add-value to CO. Recently, the first heterodinuclear Zn(ii)/Mg(ii) catalyst showed greater activity than either homodinuclear analogue ( , 137, 15078-15081). Building from this preliminary finding, here, eight new Zn(ii)/Mg(ii) heterodinuclear catalysts featuring carboxylate co-ligands are prepared and characterized.

Groups 1, 2 and Zn(II) Heterodinuclear Catalysts for Epoxide/CO Ring-Opening Copolymerization.

A series of heterodinuclear complexes are reported where both Zn(II) and a metal from Group 1 or 2 are chelated by a macrocyclic diphenolate-tetra-amine ligand. The complexes are characterized in the solid state, where relevant by single crystal X-ray crystallography and elemental analysis, and in solution, using NMR spectroscopy and mass spectrometry. The complex synthesis is achieved by reaction of the ligand with diethyl zinc to form the monozinc complex, in situ, followed by subsequent coordination of the second metal; this method enables heterodinuclear conversions >90% as determined by NMR spectroscopy.

Stable Fe(iii) phenoxyimines as selective and robust CO/epoxide coupling catalysts.

Three phenoxyimine Fe(iii)Cl complexes bearing electronically diverse -Cl, -H or -Bu substituents in the ortho position were synthesised. X-ray crystallographic analysis of the complexes reveals mononuclear structures with pentacoordinate iron centres and trigonal bipyramidal geometries. All three complexes demonstrated excellent catalytic activities towards CO/epoxide coupling to selectively form cyclic carbonates, with catalyst activity correlating with the electron withdrawing nature of the ortho-substituent (Cl > H > Bu) and thus the Lewis acidity of the metal centre.

Di-Zinc-Aryl Complexes: CO Insertions and Applications in Polymerisation Catalysis.

Two new di-zinc-aryl complexes, [LZn Ph ] and [LZn (C F ) ], coordinated by a diphenol tetraamine macrocyclic ligand have been prepared and fully characterised, including by single-crystal X-ray diffraction experiments. The complexes' reactivities with monomers including carbon dioxide, cyclohexene oxide, phthalic anhydride, isopropanol and phenol were investigated using both experimental studies and density functional theory calculations. In particular, [LZn Ph ] readily inserts carbon dioxide to form a carboxylate, at 1 bar pressure, whereas [LZn (C F ) ] does not react.

Heterodinuclear titanium/zinc catalysis: synthesis, characterization and activity for CO/epoxide copolymerization and cyclic ester polymerization.

The preparation of heterodinuclear complexes, especially those comprising early-late transition metals coordinated by a simple or symmetrical ancillary ligand, represents a fundamental challenge and an opportunity to prepare catalysts benefitting from synergic properties. Here, two new mixed titanium(iv)-zinc(ii) complexes, [LTi(OPr)ZnEt] and [LTi(OPr)ZnPh], both coordinated by a diphenolate tetra(amine) macrocyclic ligand (L), are prepared. The synthesis benefits from the discovery that reaction of the ligand with a single equivalent of titanium tetrakis(iso-propoxide) allows the efficient formation of a mono-Ti(iv) complex, [LTi(OPr)].

"Emplotted Narratives" and Structured "Behavioral Observations" Supporting the Diagnosis of Willis-Ekbom Disease/Restless Legs Syndrome in Children with Neurodevelopmental Conditions.

Background: Willis-Ekbom disease/restless legs syndrome (WED/RLS) seems to be a frequent cause of intractable chronic insomnia (ICI) but is under-recognized in children/adolescents with neurodevelopmental conditions (NDCs), as many patients do not have the ability to express the underlying "urge-to-move". In light of this, we aim to develop a protocol for behavioral observations supporting the diagnosis of WED/RLS.

Methods: We investigated 26 pediatric patients (age 1-16 years, median 8) with NDCs, ICI and evidence of familial WED/RLS employing (1) "emplotted narratives" for description of the various "urge-to-move" presentations and (2) self-description and "behavioral observations" during a "suggested clinical immobilization test" (SCIT).

Greater than the Sum of Its Parts: A Heterodinuclear Polymerization Catalyst.

Homodinuclear catalysts have good precedent for epoxide and carbon dioxide/anhydride copolymerizations; in contrast, so far pure heterodinuclear catalysts are unknown. The synthesis and properties of a heterodinuclear Zn(II)/Mg(II) complex coordinated by a symmetrical macrocyclic ligand are reported. It shows high polymerization selectivity, control, and significantly greater activity compared to either of the homodinuclear analogues or any combinations of them.

Dinuclear Zinc Salen Catalysts for the Ring Opening Copolymerization of Epoxides and Carbon Dioxide or Anhydrides.

A series of four dizinc complexes coordinated by salen or salan ligands, derived from ortho-vanillin and bearing (±)-trans-1,2-diaminocyclohexane (L1) or 2,2-dimethyl-1,3-propanediamine (L2) backbones, is reported. The complexes are characterized using a combination of X-ray crystallography, multinuclear NMR, DOSY, and MALDI-TOF spectroscopies, and elemental analysis. The stability of the dinuclear complexes depends on the ligand structure, with the most stable complexes having imine substituents.

Sensory Processing and Sleep in Typically Developing Infants and Toddlers.

Objective: To explore the relationship between sensory processing patterns and sleep problems in typically developing infants and toddlers.

Method: A retrospective chart review of 177 infants and toddlers from a community occupational therapy sleep clinic included descriptive and correlational analyses of data from the Infant/Toddler Sensory Profile and Brief Infant Sleep Questionnaire.

Results: More than half of participants (55%) demonstrated a pattern of increased sensory processing in one or more quadrants, with sensitivity being most common (36%).