Olefin triblock copolymers based on glassy polystyrene (PS), ethylene butadiene rubber (EBR) and highly crystalline polyethylene (PE) segments were prepared for the first time using a switch strategy from anionic polymerization to coordinative chain transfer (co)polymerization (CCT(co)P). PS chains obtained by anionic polymerization were transmetalated with mesitylmagnesium bromide (BrMgMes) to act as macromolecular chain transfer agents (macro-CTA, PS-MgMes) in the CCTcoP of ethylene and butadiene using {Me2Si(C13H8)2Nd(BH4)2Li(THF)}2 complex (1). Further chain extension by CCTP using pure ethylene in the monomer feed afforded well-defined PS-b-EBR-b-PE triblock copolymers. The structural, rheological and mechanical properties of these materials demonstrate excellent balance between properties and easy processability at moderate temperatures (>150 °C). We demonstrate that such triblock copolymers behave effectively as low-viscosity PS-b-EBR diblock copolymers above the melting point of PE domains and high performance thermoplastic elastomers (TPEs) upon crystallization of PE segments.

Controlled coordination polymerization of olefins and 1,3-dienes enables macromolecular engineering and, in particular, the design of new thermoplastic elastomers with high mechanical properties.

Based on DFT-level computational studies, ZnEt2 was implemented as a chain transfer agent (CTA) to promote the coordinative chain transfer (co)polymerization of ethylene for the first time with a metallocene complex of Nd. The use of ZnEt2 in combination with Mg(nBu)1.5(nOct)0.5 compared to the use of Mg(nBu)1.5(nOct)0.5 alone, improves several key aspects of the polymerization process. When ethylene is polymerized, an increase of catalytic activities is observed and narrower molar mass distributions are obtained due to reduced beta-H transfer and faster reversible chain transfer reactions. In copolymerization of ethylene with butadiene, the presence of ZnEt2 has no impact on the polymerization process in terms of polymerization kinetics and microstructure of the final copolymer. Nevertheless, it acts as an excellent CTA. Using ZnEt2 in combination with MesMgBr rather than Mg(nBu)1.5(nOct)0.5 enables selective chain transfer between neodymium and zinc and promotes a nearly quantitative chain-end functionalization with acyl chloride.

The various steps in the mechanism of olefin polymerizations mediated by neutral rare-earth metallocene complexes are discussed. The complexes are either trivalent hydride and alkyl rare-earth compounds or divalent metallocenes that are activated by the monomer via an oxidation step. The stereospecific polymerizations of conjugated dienes based on the association of a cationic metallocene complex and an alkylaluminum and the polymerization mechanism based on monomer insertion into an aluminum-carbon bond are also discussed. The exploitation of metallocene complexes for the copolymerization of olefins with conjugated dienes is the subject of a third part of this review. The synthesis of new elastomers called ethylene butadiene rubber (EBR) is highlighted. Finally, the use of rare-earth metallocenes in macromolecular engineering is detailed. This includes the synthesis of functional polyolefins and block copolymers including thermoplastic elastomers.

Exploring the surface organometallic chemistry on silica of highly electrophilic yttrium complexes is a relatively uncommon endeavor, particularly when focusing on tris-alkyl complexes characterized by Y-C sigma-alkyl bonds. A drawback with this class of complexes once grafted on silica, is the frequent occurrence of alkyl transfer by ring opening of siloxane groups, resulting in a mixture of species. Herein, we employed a more stable homoleptic yttrium allyl complex bearing bulky eta(3)-1,3-bis(trimethylsilyl)allyl ligand to limit this transfer reaction. This strategy has been validated by comparing the reactivity between [Y{ eta(3)-1,3-C3H3(SiMe3)(2)}(3)] and [Y(o-CH2PhNMe2)(3)] with SiO2-700, where the undesired alkyl transfer reaction occurred for [Y(o-CH2PhNMe2)(3)] leading to a bipodal [(equivalent to SiO)(2)Y(o-CH2PhNMe2)] as major surface species, 2, while [Y{ eta (3)-1,3-C3H3(SiMe3)(2)}(3)] resulted selectively in a monopodal species, [(equivalent to SiO)Y{eta(3)-1,3-C3H3(SiMe3)(2)}(2)], 1. The materials obtained were characterized by DRIFT, solid state NMR, mass balance analysis and EXAFS. Catalyst 1 showed high activity compared to 2 in ethylene polymerization. The catalytic performance of this neutral catalyst 1 was extended to pre-industrial scale in the presence of hydrogen and 1-hexene. An unprecedented activity, up to 7400 g(PE) g(cat)(-1) h(-1) was obtained even with very low concentration of scavenger AliBu(3) (TIBA/Y=1.2). The obtained HDPE exhibited desired spherical particle morphology with broad molar mass distribution.

Coordinative chain transfer polymerization (CCTP) of ethylene and its copolymerization with 1,3-butadiene is conducted in toluene at 80 degrees C using a combination of {(Me2Si(C13H8)2)Nd(mu-BH4)[(mu-BH4)Li(THF)]}2 (1) metal complex and various organomagnesium compounds used as chain transfer agents including n-butyl-n-octyl-magnesium (BOMAG), n-butyl-mesityl-magnesium (n-BuMgMes), n-butyl-magnesium chloride (n-BuMgCl), n-pentyl-magnesium bromide (n-C5H11MgBr), pentanediyl-1,5-di(magnesium bromide) (PDMB) and isobutyl-magnesium chloride (i-BuMgCl). Kinetics and performance in terms of control of the (co)polymerization are comparatively discussed particularly considering the presence of ether and the nature of the organomagnesium compounds employed. Taking advantage of the well-known reactivity between nitrile and molecular organomagnesium compounds, the functionalization of the chains is further carried out by deactivation of the polymerization medium with benzonitrile or methoxybenzonitrile compounds leading to ketone omega-functionalized chains. The success of the functionalizations is extended to coupling strategies using dinitrile reagents and to the functionalization of high molar mass ethylene butadiene rubber (EBR). Polyolefins such as polyethylene and poly(ethylene-co-butadiene) are synthesized by coordinative chain transfer polymerization (CCTP). The catalytic system is based on a combination of {(Me2Si(C13H8)2)Nd(mu-BH4)[(mu-BH4)Li(THF)]}2 metal complex and various organomagnesium compounds used as chain transfer agents. Nitrile compounds are implemented for the chain end functionalization and coupling reaction. image

Block copolymers based on polyethylene (PE) and ethylene butadiene rubber (EBR) were obtained by successive controlled coordinative chain transfer polymerization (CCTP) of a mixture of ethylene and butadiene (80/20) and pure ethylene. EBR-b-PE diblock copolymers were synthesized using the {Me2Si(C13H8)(2)Nd(BH4)(2)Li(THF)}2 complex in combination with n-butyl,n-octyl magnesium (BOMAG) used as both the alkylating and chain transfer agent (CTA). Triblock and multiblock copolymers featuring highly semi-crystalline PE hard segments and soft EBR segments were further obtained by the development of a bimetallic CTA, the pentanediyl-1,5-di(magnesium bromide) (PDMB). These new block copolymers undergo crystallization-driven organization into lamellar structures and exhibit a variety of mechanical properties, including excellent extensibility and elastic recovery in the case of triblock and multiblock copolymers.

The activity of various additives promoting siloxane equilibration reactions is examined and quantified on model compounds. We found in particular that the "superbase" phosphazene derivative P4 -t Bu can promote very fast exchanges (a few seconds at 90 °C) even at low concentration (<0.1 wt %). We demonstrate that permanent silicone networks can be transformed into reprocessable and recyclable dynamic networks by mere introduction of such additives. Annealing at high temperature degrades the additives and deactivates the dynamic features of the silicone networks, reverting them back into permanent networks. A simple rheological experiment and the corresponding model allow to extract the critical kinetic parameters to predict and control such deactivations.

The phenoxyimine cationic complex [(LY)-Y-1(CH2SiMe2Ph)-(THF)(3)][BArF] (L-1 = (3-Bu-t)-(O)-C6H3-CH=N-(2,6-iPr-C6H3)) was prepared starting from the homoleptic [Y(CH2SiMe2Ph)(3)(THF)(2)] yttrium complex and the phenoxyimine ligand HL1 and the subsequent cationization by the anilinium borate salt. The resulting complex was characterized by different techniques such as elemental analysis, NMR (H-1, C-13, and Y-89), and more specifically by the H-1-coupled Y-89 INEPT. The reactivity of the cationic complex toward isoprene polymerization was evaluated in the presence of trialkylaluminum. This catalyst enables the living cis-1,4 polymerization of isoprene selectively. The influence and the role played by alkylaluminum are discussed based on the screening of a set of aluminum reagents. By means of a computational mechanistic investigation performed at the DFT level, a cationic complex that accounts for the cis/trans/3,4 selectivities experimentally observed is identified. Additionally, the in silico speciation of complexes resulting from the precatalytic mixture revealed the formation of stable Y/Al heterobimetallic complexes. Finally, for comparison purposes, the cationic amidinate yttrium complex [(LY)-Y-2(CH2SiMe2Ph)(THF)(3)][B(C6F5)(4)] (L-2 = PhC(N-2,6-(Pr2C6H3)-Pr-i)(2)) was synthesized and evaluated toward isoprene polymerization under similar conditions. This complex turned out to be active and selective toward the formation of 3,4-units.

Anionic polymerization of butadiene or/and styrene is performed with lithium initiators, functional or not. The polymer chains are subsequently transferred to magnesium. The resulting polymeryl-magnesium compounds were combined with {(Me2 Si(C13 H8 )2 )Nd(μ-BH4 )[(μ-BH4 )Li(THF)]}2 metallocene complex to act as macromolecular chain transfer agents (macroCTAs) in coordinative chain transfer polymerization (CCTP) of ethylene (E) or its copolymerization (CCTcoP) with butadiene (B). Block copolymers were produced for the first time by this switch from anionic polymerization to CCTP. Hard and soft blocks such as PB, polystyrene (PS), poly(styrene-co-butadiene) (SBR) obtained by anionic polymerization and PE or poly(ethylene-co-butadiene) (EBR) produced by CCT(co)P were combined and the corresponding structures were characterized.

Block copolymers based on ethylene (E) and butadiene (B) were prepared using the ansa-bis(fluorenyl) complex {Me2Si(C13H8)(2)Nd(BH4)(2)Li(THF)}(2) in combination with (n-Bu)(n-Oct)Mg (BOMAG) as a chain-transfer agent. The diblock copolymers incorporating a soft poly(ethylene-co-butadiene) segment, called ethylene butadiene rubber (EBR), and a hard polyethylene (PE) one were obtained by simply adjusting the different feeds of monomers during the polymerization. The soluble EBR block was formed first by feeding the catalytic system dissolved in toluene at 70 degrees C with a mixture of ethylene and butadiene (E/B molar ratio 80 : 20). Then the feeding was stopped leading to the consumption of a large part of the residual monomers. The reactor was finally fed with ethylene to form the PE block. By varying the molar mass of the latter, it is shown that the resulting soft-b-hard block copolymers can self-assemble simultaneously to the growth of the PE block in agreement with a polymerization-induced self-assembly (PISA) mechanism. The self-assembly is discussed considering the reaction conditions, the crystallization of the PE block, and the polymerization mechanism involved.

A selective divalent chain transfer agent is designed to exclusively lead to polyolefin chain growth on a divalent pentanediyl moiety via coordinative chain transfer polymerization (CCTP).

A range of thermomorphic polyethylene‐supported organocatalysts is prepared from N ‐alkyl imidazoles and polyethylene iodide (PEI) with good yields (85–92%) and high funtionality (98–99%). The catalytic activity of these species is studied for the ring opening of epoxidized methyl oleate with CO 2 to give the corresponding cyclic carbonate. The reaction is carried out at 100 °C to fully exploit the thermomorphic behavior of the organocatalysts. The optimized conditions (neat, 100 °C, and 20 bar of CO 2 ) are applied to a range of epoxidized fatty acids, including an epoxidized rapeseed oil, to give the corresponding carbonates with good yields (75–96%). The catalyst recycling is also studied, and no significant loss of activity is observed after ten runs. The fatty carbonates are important intermediates for the preparation of non‐isocyanate polyurethanes (NIPUs).

Monocationic complexes of yttrium with various bis-alkyl and bis-allyl ligands Y(CH2SiMe2Ph)(2)(THF)(4)][B(C6F5)(4)], [Y-(CH2C6H4NMe2)(2)(THF)(2)][B(C(6)Fs)(4)], and [Y[1,3-(SiMe3)(2)C3H3](2) (THF)(2)][B-(C6F5)(4)] have been prepared by protonolysis of the corresponding homoleptic tris-alkyl or -allyl complexes using the anilinium borate salt [PhNMe2H][B-(C6F3)(4)]. The resulting ion-pair complexes have been isolated and characterized by different techniques such as elemental analysis, H-1, C-13, and Y-89 NMR, and EXAFS for the allyl cationic complex [Y[1,3-(SiMe3)(2)C3H3](2) (THF)(2)][B(C(6)Fs)(4)]. More specifically, a H-1-coupled Y-89 INEPT sequence has been developed in order to quantify the metal/alkyl ligand stoichiometry of both synthesized neutral tris-alkyl and cationic bis-alkyl yttrium complexes. The activity of the cationic complexes toward ethylene and isoprene homopolymerization has been assessed. In presence of TiBA, polyethylene was produced with activities ranging from 6 to 26 kg(PE) mol(Y)(-1) h(-1) bar(-1). The molar mass of the yielded polymers shows a bimodal distribution. Under similar conditions, polyisoprene was produced up to full conversion of the monomer. The microstructure of the yielded polyisoprene displayed mainly cis-1,4-units (ca. 60-70%) and 3,4-units (ca. 20-30%). Only a few percent of trans-1,4 units was revealed.

The organocatalytic synthesis of vinylene carbonates from benzoins and acyloins was studied using diphenyl carbonate as a carbonyl source. A range of N-Heterocyclic Carbene (NHC) precursors were screened and it was found that imidazolium salts were the most active for this transformation. The reaction occurs at 90°C under solvent-free conditions. A wide range of vinylene carbonates (symmetrical and unsymmetrical, aromatic or aliphatic), including some derived from natural products, were prepared with 20-99% isolated yields (24 examples). The reaction was also developed using thermomorphic polyethylene-supported organocatalysts as recoverable and recyclable species. The use of such species facilitates the workup and allows the synthesis of vinylene carbonates on the preparative scale (> 30 g after 5 runs).

The organocatalytic synthesis of substituted vinylene carbonates from benzoins and acyloins was studied using diphenyl carbonate as a carbonyl source. A range of N-Heterocyclic Carbene (NHC) precursors were screened and it was found that imidazolium salts were the most active for this transformation. The reaction occurs at 90 degrees C under solvent-free conditions. A wide range of substituted vinylene carbonates (symmetrical and unsymmetrical, aromatic or aliphatic), including some derived from natural products, were prepared with 20-99% isolated yields (24 examples). The reaction was also developed using thermomorphic polyethylene-supported organocatalysts as recoverable and recyclable species. The use of such species facilitates the workup and allows the synthesis of vinylene carbonates on the preparative scale (>30 g after 5 runs).

An imidazolium catalyst supported on thermomorphic polyethylene (PE) was prepared from 1-methylimidazole and polyethylene iodide (PE-I). The catalyst was characterized by H-1 and C-13 NMR, SEC and MALDI-ToF mass spectrometry. Its catalytic activity was evaluated in the ring-opening of epoxides with carbon dioxide to give cyclic carbonates under solvent-free conditions. The catalyst proved to be active at low catalyst loading (down to 0.1 mol%) and allows the reaction to occur at low CO2 pressure (1-5 bar) and moderate temperature (100 degrees C). A range of terminal and internal epoxides was converted to the corresponding cyclic carbonates with high yields and selectivities. The recyclability of the catalyst was studied and no significant loss of activity was observed after 5 runs.

Background Medication errors have a high prevalence in surgery and management of home medication is strongly involved in these errors. In scheduled surgery, the preoperative consultation is a privileged time to inform the patient about the management of her/his home medication before admission. This study assessed the impact of a pre-anesthesia best possible medication history (PA-BPMH) on admission. The PA-BPMH was performed by a clinical pharmacist prior to the anesthesia consultation for anesthesiologists to prescribe admission medical orders for scheduled orthopedic surgery patients. Methods This was a prospective observational study which was carried out in an orthopedic surgery department. All patients over 18 years old with an elective orthopedic surgery were eligible except ambulatory surgery patients. The pharmacist registered the PA-BPMH into the software making it available for anesthesiologists for the pre-admission medication order. Finally, a medication reconciliation was performed at admission. The main outcome was the percentage of patients with at least one unintended medication discrepancy (UMD) at admission. The nature, potential clinical impact and acceptance rate of each UMD detected were assessed. Also, the PA-BPMH process was described and patients and anesthesiologists satisfaction was evaluated. Results A total of 455 patients had a pharmaceutical consultation. Medication reconciliation was performed at admission for 360 patients. Overall, at least one UMD was observed in 13.0% of patients (n = 47). A total of 63 UMD were detected. The most common type of UMD was omission (25.4%) and incorrect drug (23.8%).Two UMD (3.2%) were evaluated as life threatening. All the UMD detected were corrected on the admission medication order. Conclusion A preoperative pharmacist-anesthesiologist teamwork seems to improve the safety of perioperative management of home medication for scheduled orthopedic surgery patients. This process needs a randomized clinical trial across a wider range of surgeries before its implementation.