Building Block For Polymers Research Articles

Review of old chemistry and new catalytic advances in the on-purpose synthesis of butadiene.

Increasing demand for renewable feedstock-based chemicals is driving the interest of both academic and industrial research to substitute petrochemicals with renewable chemicals from biomass-derived resources. The search towards novel platform chemicals is challenging and rewarding, but the main research activities are concentrated on finding efficient pathways to produce familiar drop-in chemicals and polymer building blocks. A diversity of industrially important monomers like alkenes, conjugated dienes, unsaturated carboxylic acids and aromatic compounds are thus targeted from renewable feedstock. In this context, on-purpose production of 1,3-butadiene from biomass-derived feedstock is an interesting example as its production is under pressure by uncertainty of the conventional fossil feedstock. Ethanol, obtained via fermentation or (biomass-generated) syngas, can be converted to butadiene, although there is no large commercial activity today. Though practised on a large scale in the beginning of the 20th century, there is a growing worldwide renewed interest in the butadiene-from-ethanol route. An alternative route to produce butadiene from biomass is through direct carbohydrate and gas fermentation or indirectly via the dehydration of butanediols. This review starts with a brief discussion on the different feedstock possibilities to produce butadiene, followed by a comprehensive summary of the current state of knowledge regarding advances and achievements in the field of the chemocatalytic conversion of ethanol and butanediols to butadiene, including thermodynamics and kinetic aspects of the reactions with discussions on the reaction pathways and the type of catalysts developed.

Synthesis and self-assembly of well-defined elastin-like polypeptide-poly(ethylene glycol) conjugates.

A series of stimulus-responsive elastin-like polypeptide-poly(ethylene glycol) (ELP-PEG) block copolymers was synthesized. The polymeric building blocks were conjugated via the efficient and specific strain-promoted alkyne-azide cycloaddition (SPAAC). For this purpose, ELP and PEG blocks were functionalized with azide and cyclooctyne moieties, respectively. Azides were introduced by applying a recently developed pH-controlled diazotransfer reaction on the primary amines present in ELP (N-terminus and lysine side chains). By varying pH, ELP-blocks with one or two azides were obtained, which subsequently allowed us to synthesize both ELP-PEG diblock copolymers and miktoarm star polymers. Triggering the phase transition of the ELP-block resulted in the formation of an amphiphilic block copolymer, which self-assembled into micelles. This is the first example of an ELP-containing hybrid block copolymer in which PEG as the hydrophilic corona-forming domain is combined with a stimulus-responsive ELP-block. The encapsulation of a hydrophobic fluorescent dye was shown to exemplify the potential of the micelles to serve as nanocarriers for hydrophobic drugs, with the PEG corona providing stealth and steric protection of encapsulated materials.

Artificial enzyme cascade to the polymer building block ω-amino caproic acid

Artificial enzyme cascade to the polymer building block ω-amino caproic acid

From zero to hero – Production of bio-based nylon from renewable resources using engineered Corynebacterium glutamicum

Polyamides are important industrial polymers. Currently, they are produced exclusively from petrochemical monomers. Herein, we report the production of a novel bio-nylon, PA5.10 through an integration of biological and chemical approaches. First, systems metabolic engineering of Corynebacterium glutamicum was used to create an effective microbial cell factory for the production of diaminopentane as the polymer building block. In this way, a hyper-producer, with a high diaminopentane yield of 41% in shake flask culture, was generated. Subsequent fed-batch production of C. glutamicum DAP-16 allowed a molar yield of 50%, a productivity of 2.2gL−1h−1, and a final titer of 88gL−1. The streamlined producer accumulated diaminopentane without generating any by-products. Solvent extraction from alkalized broth and two-step distillation provided highly pure diaminopentane (99.8%), which was then directly accessible for poly-condensation. Chemical polymerization with sebacic acid, a ten-carbon dicarboxylic acid derived from castor plant oil, yielded the bio-nylon, PA5.10. In pure form and reinforced with glass fibers, the novel 100% bio-polyamide achieved an excellent melting temperature and the mechanical strength of the well-established petrochemical polymers, PA6 and PA6.6. It even outperformed the oil-based products in terms of having a 6% lower density. It thus holds high promise for applications in energy-friendly transportation. The demonstration of a novel route for generation of bio-based nylon from renewable sources opens the way to production of sustainable bio-polymers with enhanced material properties and represents a milestone in industrial production.

Engineering responsive polymer building blocks with host-guest molecular recognition for functional applications.

CONSPECTUS: All living organisms and soft matter are intrinsically responsive and adaptive to external stimuli. Inspired by this fact, tremendous effort aiming to emulate subtle responsive features exhibited by nature has spurred the invention of a diverse range of responsive polymeric materials. Conventional stimuli-responsive polymers are constructed via covalent bonds and can undergo reversible or irreversible changes in chemical structures, physicochemical properties, or both in response to a variety of external stimuli. They have been imparted with a variety of emerging applications including drug and gene delivery, optical sensing and imaging, diagnostics and therapies, smart coatings and textiles, and tissue engineering. On the other hand, in comparison with molecular chemistry held by covalent bonds, supramolecular chemistry built on weak and reversible noncovalent interactions has emerged as a powerful and versatile strategy for materials fabrication due to its facile accessibility, extraordinary reversibility and adaptivity, and potent applications in diverse fields. Typically involving more than one type of noncovalent interactions (e.g., hydrogen bonding, metal coordination, hydrophobic association, electrostatic interactions, van der Waals forces, and π-π stacking), host-guest recognition refers to the formation of supramolecular inclusion complexes between two or more entities connected together in a highly controlled and cooperative manner. The inherently reversible and adaptive nature of host-guest molecular recognition chemistry, stemming from multiple noncovalent interactions, has opened up a new platform to construct novel types of stimuli-responsive materials. The introduction of host-guest chemistry not only enriches the realm of responsive materials but also confers them with promising new applications. Most intriguingly, the integration of responsive polymer building blocks with host-guest recognition motifs will endow the former with further broadened responsiveness to external stimuli and accordingly more sophisticated functions. In this Account, we summarize recent progress in the field of responsive polymeric materials containing host-guest recognition motifs with selected examples and highlight their versatile functional applications, whereas small molecule-oriented host-guest supramolecular systems are excluded. We demonstrate how the introduction of host-guest chemistry into conventional polymer systems can modulate their responsive modes to external stimuli. Moreover, the responsive specificity and selectivity of polymeric systems can also be inherited from the host-guest recognition motifs, and these features provide extra advantages in terms of function integration. The following discussions are categorized in terms of design and functions, namely, host-guest chemistry toward the fabrication of responsive polymers and assemblies, optical sensing and imaging, drug and gene delivery, and self-healing materials. A concluding remark on future developments is also presented. We wish this prosperous field would incur more original and evolutionary ideas and benefit fundamental research and our daily life in a more convenient way.

Enzyme-Triggered Cascade Reactions and Assembly of Abiotic Block Copolymers into Micellar Nanostructures

Catalytic action of an enzyme is shown to transform a non-assembling block copolymer, composed of a completely non-natural repeat unit structure, into a self-assembling polymer building block. To achieve this, poly(styrene) is combined with an enzyme-sensitive methacrylate-based polymer segment carrying carefully designed azobenzene side chains. Once exposed to the enzyme azoreductase, in the presence of coenzyme NADPH, the azobenzene linkages undergo a bond scission reaction. This triggers a spontaneous 1,6-self-elimination cascade process and transforms the initially hydrophobic methacrylate polymer segment into a hydrophilic hydroxyethyl methacrylate structure. This change in chemical polarity of one of the polymer blocks confers an amphiphilic character to the diblock copolymer and permits it to self-assemble into a micellar nanostructure in water.

Cooperative Macromolecular Self-Assembly toward Polymeric Assemblies with Multiple and Bioactive Functions

In the past decades, polymer based nanoscale polymeric assemblies have attracted continuous interest due to their potential applications in many fields, such as nanomedicine. Many efforts have been dedicated to tailoring the three-dimensional architecture and the placement of functional groups at well-defined positions within the polymeric assemblies, aiming to augment their function. To achieve such goals, in one way, novel polymeric building blocks can be designed by controlled living polymerization methodology and advanced chemical modifications. In contrast, by focusing on the end function, others and we have been practicing strategies of cooperative self-assembly of multiple polymeric building blocks chosen from the vast library of conventional block polymers which are easily available. The advantages of such strategies lie in the simplicity of the preparation process and versatile choice of the constituent polymers in terms of their chemical structure and functionality as well as the fact that cooperative self-assembly based on supramolecular interactions offers elegant and energy-efficient bottom-up strategies. Combination of these principles has been exploited to optimize the architecture of polymeric assemblies with improved function, to impart new functionality into micelles and to realize polymeric nanocomplexes exhibiting functional integration, similar to some natural systems like artificial viruses, molecular chaperones, multiple enzyme systems, and so forth. In this Account, we shall first summarize several straightforward designing principles with which cooperative assembly of multiple polymeric building blocks can be implemented, aiming to construct polymeric nanoassemblies with hierarchal structure and enhanced functionalities. Next, examples will be discussed to demonstrate the possibility to create multifunctional nanoparticles by combination of the designing principles and judiciously choosing of the building blocks. We focus on multifunctional nanoparticles which can partially address challenges widely existing in nanomedicine such as long blood circulation, efficient cellular uptake, and controllable release of payloads. Finally, bioactive polymeric assemblies, which have certain functions closely mimicking those of some natural systems, will be used to conceive the concept of functional integration.

Ruthenium-catalysed alkoxycarbonylation of alkenes with carbon dioxide

Alkene carbonylations represent a major technology for the production of value-added bulk and fine chemicals. Nowadays, all industrial carbonylation processes make use of highly toxic and flammable carbon monoxide. Here we show the application of abundantly available carbon dioxide as C1 building block for the alkoxycarbonylations of industrially important olefins in the presence of a convenient and inexpensive ruthenium catalyst system. In our system, carbon dioxide works much better than the traditional combination of carbon monoxide and alcohols. The unprecedented in situ formation of carbon monoxide from carbon dioxide and alcohols permits an efficient synthesis of carboxylic acid esters, which can be used as detergents and polymer-building blocks. Notably, this transformation allows the catalytic formation of C-C bonds with carbon dioxide as C1 source and avoids the use of sensitive and/or expensive reducing agents (for example, Grignard reagents, diethylzinc or triethylaluminum).

Cyclic polymers as a building block for cyclic brush polymers and gels

Cyclic polymers, as one of the oldest topological polymers, are undergoing resurgence. This is largely ascribed to the significant achievements in modern polymer chemistry. The novel ring-expansion techniques have conveniently produced varied cyclic polymers with highly topological purity and on large scales, which should facilitate their use in the near future. Beyond the monocyclic molecular conformations, the combination of controlled polymerization techniques and click chemistry have established a robust strategy for preparing cyclic polymers with more complex architectures, such as theta, eight, and tadpole shapes. This diversification in cyclic polymer composition and conformation significantly broadens interest in the cyclic polymers. However, compared to the synthesis achievements, the exploration of cyclic polymer property and application are lagging behind. Recently, we explored the ring-expansion metathesis polymerization on various functional ring-strained olefin monomers to produce cyclic functional polymers, which were then used as the building blocks to fabricate cyclic brush polymers and cyclic gel materials and will be discussed here.

Carbon dioxide (CO2) as sustainable feedstock for polyurethane production

A dream comes true: tailor-made polyethercarbonate polyols are synthesised from propylene oxide and CO2. Molecular weight and functionality of these polyethercarbonate polyols are controlled by the use of an appropriate alcohol starter enabling innovative applications as a polymer building block. Interestingly, the properties of the polyethercarbonate polyols can be adjusted in a wide range by tuning CO2 content and architecture. The feasibility of using such tailored polyethercarbonate polyols in the production of polyurethanes is demonstrated as a prime example for a novel CO2 utilization with industrial potential.

A New Building Block for Low Band Gap Polymers

A New Building Block for Low Band Gap Polymers

A New, Strongly Electron-Donating Building Block for Low-Bandgap Polymers

A New, Strongly Electron-Donating Building Block for Low-Bandgap Polymers

Interfacial assembly of protein–polymer nano-conjugates into stimulus-responsive biomimetic protocells

The mechanism of spontaneous assembly of microscale compartments is a central question for the origin of life, and has technological repercussions in diverse areas such as materials science, catalysis, biotechnology and biomedicine. Such compartments need to be semi-permeable, structurally robust and capable of housing assemblages of functional components for internalized chemical transformations. In principle, proteins should be ideal building blocks for the construction of membrane-bound compartments but protein vesicles with cell-like properties are extremely rare. Here we present an approach to the interfacial assembly of protein-based micro-compartments (proteinosomes) that are delineated by a semi-permeable, stimulus-responsive, enzymatically active, elastic membrane consisting of a closely packed monolayer of conjugated protein-polymer building blocks. The proteinosomes can be dispersed in oil or water, thermally cycled to temperatures of 70 °C, and partially dried and re-inflated without loss of structural integrity. As a consequence, they exhibit protocellular properties such as guest molecule encapsulation, selective permeability, gene-directed protein synthesis and membrane-gated internalized enzyme catalysis.

A New, Strongly Electron-Donating Building Block for Low-Bandgap Polymers

Corrected by: A New, Strongly Electron-Donating Building Block for Low-Bandgap PolymersSynfacts 2013; 9(09): 1029-1029DOI: 10.1055/s-0033-1339687

Bis(3-cyano-pentane-2,4-dionato) Co(II) as a linear building block for coordination polymers: combinations with two polypyridines

Two types of bis(β-diketonato) Co(II) complexes, [Co(CNacac)2] (CNacac = 3-cyano-pentane-2,4-dionato), and [Co(dbm)2] (dbm = dibenzoylmethanato or 1,3-diphenyl-propane-1,3-dionato) were examined as linear building blocks for the construction of coordination polymers in combination with two oligopyridines, 1,4-bis(4,2’:6’,4”-terpyridin-4’-yl)benzene (L1) and 1,3-bis(3,2’:6’,3”-terpyridin-4’-yl)benzene) (L2). From combinations of [Co(CNacac)2] with L1 and L2, 2-D coordination polymers, [Co(CNacac)2]2(L1)·(CHCl3)·(CH3OH) (CoCN-1) and [Co(CNacac)2](L2)1/2·(tetrachloroethane)3/2 (CoCN-2), are obtained. Both CoCN-1 and CoCN-2 have 2D (4,4) net structures, in which L1 and L2 are tetradentate. In contrast, combination of [Co(dbm)2] with L2 affords a 1-D coordination polymer, [Co(dbm)2](L2)·4(CH3OH) (Codbm-1), in which L2 is bidentate. L2 as a tetradentate ligand was inhibited by bulky phenyl rings in [Co(dbm)2]. These results indicate that [Co(CNacac)2] with a relatively simplified structure is useful as a linear building block in combinations with bulky oligopyridines.

Diketopyrrolopyrrole: A versatile building block for organic photovoltaic materials

In recent years, diketopyrrolopyrroles (DPPs) have become one of the extensively studied organic building blocks of oligomers and polymers having promising optoelectronic properties, especially in organic solar cells. There are a large number of reports on structural modification of DPP cores to improve their properties in devices. There is plenty of room left for research in the field of structural modification and bandgap engineering to maintain energy level alignment and to achieve optimum morphology/crystallinity leading to high performance in organic photovoltaic (OPV) devices. This article reviews the DPP containing materials and their variants as potential active layer materials for OPV devices. An attempt has been made to go through their synthesis, structure and optoelectronic properties in such a way that any future efforts to modify this versatile structure have benefited. Open image in new window

In(SAr)3 As a Building Block for 3D and Helical Coordination Polymers

In(SAr)3 (Ar = phenyl or p-tolyl) was employed as a building block to construct coordination polymers [(In(SPh)3)3(tpt)2] (1, tpt = 2,4,6-tris(4-pyridyl)triazine), [In(SPh)2(2-PCIH)] (2, 2-HPCIH = 2-pyridinecarbaldehyde isonicotinoylhydrazone), and [(In(S(p-tol))2)(2-PCIH)]·2MeOH (3). Compound 1 is an intricate 3D coordination polymer displaying superstructure effects on its X-ray diffraction pattern, which have been additionally studied by transmission electron microscopy (TEM). Compounds 2 and 3 are helical coordination polymers. Whereas 3 comprises helices of both rotational handednesses in its crystal structure, 2 possesses only one enantiomeric form and thus exhibits a noncentrosymmetric structure that displays an SHG effect.

Mild Oxidation of Thiofunctional Polymers to Cytocompatible and Stimuli‐Sensitive Hydrogels and Nanogels

Nanogels consist of three dimensionally cross-linked hydrophilic polymer chains and can thus be easily modified through functionalization of the polymeric building blocks, for example to yield stimuli-sensitive materials. For drug transport and intracellular release, redox-sensitive systems are especially of interest, as the intracellular space is reductive. In this study, parameters that allow preparation of nanogels with tunable size between 150 and 350 nm are systematically evaluated and identified. Most importantly, a new and mild oxidation catalyst, alloxan, is introduced for the preparation of the nanogels. This broadens the range of possible payloads to more-sensitive molecules. Particle stability, degradation in cytosolic conditions, and cytocompatibility in concentrations up to 10 mg · mL(-1) are demonstrated.

Desorption Electrospray Ionization Imaging Mass Spectrometry as a Tool for Investigating Model Prebiotic Reactions on Mineral Surfaces.

Mineral-assisted thermal decomposition of formamide (HCONH(2)) is a heavily studied model prebiotic reaction that has offered valuable insights into the plausible pathways leading to the chemical building blocks of primordial informational polymers. To date, most efforts have focused on the analysis of formamide reaction products released in solution, although several studies have examined the role of mineral catalysts in promoting this chemistry. We show here that the direct investigation of reactive mineral surfaces by desorption electrospray ionization-mass spectrometry imaging (DESI-MSI) gives a new perspective on the important role of the mineral surface in the formation of reaction products. As a proof-of-principle example, we show that DESI-MSI allows interrogation of the molecular products produced on heterogeneous granite samples with minimal sample preparation. Purine and pyrimidine nucleobases and their derivatives are successfully detected by DESI-MSI, with a strong correlation of the spatial product distribution with the mineral microenvironment. To our knowledge, this study is the first application of DESI-MSI to the study of complex and porous mineral surfaces and their roles in chemical evolution. This DESI-MSI approach is generally applicable to a wide range of reactions or other processes involving minerals.

Synthesis of pyridine-capped diketopyrrolopyrrole and its use as a building block of low band-gap polymers for efficient polymer solar cells

A new building block for low band-gap polymers, diketopyrrolopyrrole (DPP) flanked by pyridine (PyDPP), has been synthesized via a simple synthetic route. PyDPP was polymerized with bithiophene (BT) to afford a low band-gap copolymer (PBTPyDPP) which was used as an electron donor of the active layer in polymer solar cells. The solar cell device based on PBTPyDPP exhibited a promising PCE of 4.9% with a high VOC over 0.9 V, which is one of the highest values among DPP-based polymer solar cells.