New ring-opening polymerizations for copolymers having controlled microstructures

In Vitro Evaluation of Acrylic Adhesives in Lymphatic Fluids-Influence of Glue Type and Procedural Parameters

To evaluate the embolic properties of different acrylic adhesive/iodized oil mixtures for lymphatic interventions. Polymerization of histoacryl (HA) (Bayer Healthcare) and glubran 2 (GL) (GEM) mixed with iodized oil (ratios 1:0–1:7) were investigated in lymphatic fluids with low and high triglyceride (low TG & high TG) contents. Static polymerization time and dynamic polymerization experiments with different volumes of glucose flush (1, 2 and 5 mL) were performed to simulate thoracic duct embolization. For both glues, static polymerization times were longer when the iodized oil content was increased and when performed in high TG lymphatic fluid. In the dynamic experiments, the prolongation of polymerization due to the oil content and TG levels was less pronounced for both glue types. Increased lymphatic flow rates decreased embolization times for low glue/oil ratios while preventing embolization for high glue/oil ratios. Higher glucose flush volumes increased occlusion times. Polymerization times of acrylic glue in a lymphatic fluid are prolonged by increasing the iodized oil concentration and triglyceride concentration as well as by using larger volumes of glucose flush. Increased lymphatic flow rates decrease embolization times for low glue/oil ratios and may prevent embolization for high glue/oil ratios.

Radical Ring-Closing/Ring-Opening Cascade Polymerization

A novel strategy for the synthesis of main-chain polymers through radical ring-closing/ring-opening cascade polymerization is reported. Efficient radical cyclopolymerization was achieved through systematic optimization of the electronic properties of 1,6-diene structures. Fusing 1,6-diene with allylic sulfide or allylic sulfone motifs enabled a ring-closing/ring-opening cascade reaction that provides a strong driving force for the ring-opening polymerization of large macrocyclic monomers. The ability of 1,6-diene-fused allylic sulfone to undergo efficient SO₂ extrusion generated a propagating alkyl radical capable of reversible deactivation. This strategy provides a general platform for the synthesis of polymers incorporating complex main-chain structures and degradable functionalities.

End-functional polyolefins for block copolymer synthesis

Polyolefins that contain polar functionalities are highly desired because they could extend the range of applications of these low production cost materials by modifying surface and other interfacial properties. Block copolymers containing polyolefin and polar segments are among the most sought-after architectures because of their ability to span the phase boundaries. This review focusses on the end-functionalisation of polyolefins by catalytic olefin polymerisation processes, almost invariably by metal-catalysed routes, followed by the growth polar blocks by various polymerisation techniques.

Fluorinated polymer surfactants bearing an alternating peptide skeleton prepared by three-component polycondensation

A new species of fluorinated polymer surfactant was developed by three component polycondensation analogous to Ugi four-component condensation. The surfactant exhibited unique surface properties, which made cellulose-based materials hydrophobic and decreased the surface tension of CHCl₃. It turned out that the polymer forms micelles in CHCl₃.

A new species of fluorinated polymer surfactant was developed by three component polycondensation analogous to Ugi four-component condensation.

One-pot synthesis of alternating peptides exploiting a new polymerization technique based on Ugi's 4CC reaction

A catalyst-free, one-pot synthetic technique for alternating peptides was developed on the basis of Ugi's 4 component condensation reaction.

Synthesis and thermal properties of vinyl copolymers with phenyl vinylethylene carbonate and N-substituted maleimides undergoing color change with acid–base switching

The solution of P(PVEC-co-NMI), having an alternating structure, was a red color in basic solvents and the solution color changed with a high sensitively to acid–base switching.

Exclusive One-Way Cycle Sequence Control in Cationic Terpolymerization of General-Purpose Monomers via Concurrent Vinyl-Addition, Ring-Opening, and Carbonyl-Addition Mechanisms

Cationic terpolymerization of vinyl ether (VE), oxirane, and ketone successfully proceeded via unprecedented concurrent vinyl-addition, ring-opening, and carbonyl-addition mechanisms. In particular, the use of cyclohexene oxide as an oxirane resulted in terpolymerization via an exclusive one-way cycle, i.e., the reactions occurred only in the VE → oxirane, oxirane → ketone, and ketone → VE directions. Terpolymers that have repeating units of (VE_∼2-oxirane_∼2-ketone)_n were obtained under appropriate conditions. In addition, no two-monomer combination achieved efficient copolymerization, which suggests that three specific types of crossover reactions are required for successful terpolymerization. The presence of a ketone, a compound that has rarely been employed as a monomer, is indispensable for a one-way cycle: terpolymerization also proceeded with an aliphatic aldehyde but resulted in two-way crossover reactions at the aldehyde-derived propagating ends.

Aqueous radical addition-coupling polymerization for the synthesis of hydrophilic periodic polymer

A hydrophilic polymer possessing a [AB_xAC]_n (A = ester, B = ethylene oxide, C = N–O) repeating sequence was synthesized by an aqueous radical addition-coupling polymerization using water-soluble dibromide and a nitroso compound in the presence of a CuBr/ligand.

Combination of ATRA and ATRC for the synthesis of periodic vinyl copolymers

A new approach to periodic vinyl copolymers via combination of atom transfer radical addition (ATRA) and atom transfer radical coupling (ATRC) is reported. The two examples are methyl methacrylate (MMA) and styrene (St) periodic copolymer (P(SMMS)) and acrylonitrile (AN) and St periodic copolymer (P(SAAS)). First, two monomer sequence units (MSU) with built-in sequence, SMMS and SAAS, are synthesized through the controlled ATRA of two ATRP initiators with St. Then, the ATRC of SMMS and SAAS are conducted at high radical conditions to generate two types of high-molecular-weight copolymers, P(SMMS) and P(SAAS). Though side reactions can not be totally avoided, characterizations of the polymer structure with a variety of means confirm that the main chain structures of P(SMMS) and (PSAAS) are predominantly with the periodic sequences from the MSUs. Attempts to suppress the side reactions are successful via the MNP-mediated ATRC of SMMS and SAAS.

Synthesis of Sequence-Specific Vinyl Copolymers by Regioselective ROMP of Multiply Substituted Cyclooctenes

A variety of multisubstituted cyclooctenes were prepared and employed as monomers for ring-opening metathesis polymerization using the Grubbs second or third generation catalysts. The resulting polymers were characterized by NMR spectroscopy, size exclusion chromatography, and differential scanning calorimetry. Monomers possessing a substituent at the 3-position afforded highly regio- and stereoregular polyalkenamers, from which the corresponding sequence-specific vinyl quaterpolymers were obtained upon hydrogenation. Simultaneous control of tacticity was also demonstrated by employing monomers with defined stereochemistry.

Sequence Regulated Poly(ester-amide)s Based on Passerini Reaction

Multicomponent polymerization based on Passerini reaction is described. Room temperature polymerization of dicarboxyl acid, monoaldehyde, and diisocyanide leads to the formation of a new type of sequence regulated poly(ester-amide)s in an efficient one-pot process. The polymerization was confirmed to be a stepwise mechanism, and the resulting polymers were characterized and determined to be linear polymers with a sequence regulated backbone repeating unit of ester-ester-amide-amide. When functional aldehydes were used, functional side groups could be easily introduced at the same time, providing a simple way for further modification.

Metal-catalyzed synthesis of alternating copolymers

The creation of polymers with a high degree of sequence and/or stereocontrol represents an exciting frontier in materials science. In order to obtain alternating polymers, coordination polymerization using well-defined metal complexes has played a leading role in the last two decades. In the following paper, we will describe selected published efforts to achieve these research goals using discrete, structurally well-characterized metal complexes.

Sequence control in polymer synthesis

The control over comonomer sequences is barely studied in macromolecular science nowadays. This is an astonishing situation, taking into account that sequence-defined polymers such as nucleic acids and proteins are key components of the living world. In fact, fascinating biological machines such as enzymes, transport proteins, cytochromes or sensory receptors would certainly not exist if evolution had not favored chemical pathways for controlling chirality and sequences. Thus, it seems obvious that synthetic polymers with controlled monomer sequences have an enormous role to play in the materials science of the next centuries. The goal of this tutorial review is to shed light on this highly important but embryonic field of research. Both biological and synthetic mechanisms for controlling sequences in polymerization processes are critically discussed herein. This state-of-the-art overview may serve as a source of inspiration for the development of new generations of synthetic macromolecules.

Synthesis of copolymers by alternating ROMP (AROMP)

The alternating polymerization of cyclobutene 1-carboxylic esters and cyclohexene derivatives with the precatalyst [(H(2)IMes)(3-Br-pyr)(2)Cl(2)Ru=CHPh] is described. This reaction is synthetically accessible and provides (AB)(n) heteropolymers with an alternating backbone and alternating functionality. The regiocontrol of heteropolymer formation derives from the inability of the cyclobutene ester and cyclohexene monomers to undergo homopolymerization in combination with the favorable kinetics of cross polymerization.