Preparation Of Polymeric Materials Research Articles

Improving the marine biodegradability of poly(alkylene succinate)-based copolymers

AbstractWe report the syntheses of novel marine biodegradable poly(ethylene succinate) (PES)- and poly(butylene succinate) (PBS)-based copolymers containing different dicarboxylic acid (DCA) units with various carbon numbers and different feed ratios. Biochemical oxygen demand tests demonstrated that some of the obtained PES- and PBS-based copolymers were biodegradable in seawater. Specifically, polymers with longer-chain DCA units, even at low contents, exhibited marine biodegradability. The thermomechanical properties of the copolymers, such as their thermal stabilities, melting points, glass transition temperatures, tensile moduli, strains at break, and stresses at break, also varied with the DCA contents. These results indicated that the thermomechanical properties and the marine biodegradabilities of the PES- and PBS-based copolymers were regulated by controlling their structures and DCA contents. The polymers obtained in this study may replace general-purpose polymers. Our approach may also be applicable to other polymeric materials. Furthermore, our findings pave the way for the rational design and preparation of polymeric materials that are biodegradable in environments other than oceans and have good thermomechanical properties.

Reversed Controlled Polymerization (RCP): Depolymerization from Well-Defined Polymers to Monomers

Controlled polymerization methods are well-established synthetic protocols for the design and preparation of polymeric materials with a high degree of precision over molar mass and architecture. Exciting recent work has shown that the high end-group fidelity and/or functionality inherent in these techniques can enable new routes to depolymerization under relatively mild conditions. Converting polymers back to pure monomers by depolymerization is a potential solution to the environmental and ecological concerns associated with the ultimate fate of polymers. This perspective focuses on the emerging field of depolymerization from polymers synthesized by controlled polymerizations including radical, ionic, and metathesis polymerizations. We provide a critical review of current literature categorized according to polymerization technique and explore numerous concepts and ideas which could be implemented to further enhance depolymerization including lower temperature systems, catalytic depolymerization, increasing polymer scope, and controlled depolymerization.

Stretchable elastomers with self-healing and shape memory properties based on functionalized TMC and DLLA copolymers

The preparation of polymeric materials with many advantages is a hot topic in materials research. However, the development of materials with simultaneous self-healing ability, high mechanical properties, and shape memory remains a challenge. This study successfully prepared novel multifunctional polycarbonate elastomers of 5-methyl-5-benzyloxycarbonyl-1,3-dioxane-2-one (MBC) and d, l-lactic acid (DLLA), using mPEG as the initiator. The structures of the elastomers were characterized by FT-IR, indicating that the resulting polymers are physically cross-linked structures formed by hydrogen bonding. The physical properties of the elastomers were investigated using DSC, TGA, self-healing tests, uniaxial tensile tests, and shape memory tests. The resulting elastomer (MBC: DLLA = 4: 1) exhibited an impressive tensile strain as high as 1443% and completed its self-healing behaviour within 110 min at room temperature, the elastomer (MBC: DLLA = 6: 1) showed markedly greater tensile stress of 1.38 MPa, and the elastomer (MBC: DLLA = 7: 1) recovered more than 98% of its original shape within 51 sec. Due to their unique properties, the obtained elastomers could be promising candidates for intelligent medical materials.

(Invited) A New Frontier in Hybrid Inorganic-Organic Membranes for Redox Flow Batteries: The Polyketone-Based Membranes

Zinc iodide flow batteries (ZIFBs) are amongst the most promising chemistries to substitute the expensive and less energy intensive Vanadium Flow Batteries (VFBs). One of main problems related to this technology is the crossover of water due to the transport of Zn2+. One possible approach is the development of new ion-exchange membranes (IEMs). For practical applications they are required to possess high ionic conductivity, high thermal stability, long lifetime, and electrical insulation. The preparation of polymeric materials with such high-performance properties is still challenging and can lead to high prices, hindering their widespread use in energy conversion technologies. This is even more difficult when considering anion conducting membranes [1-3].Polyketones (PK) are known to be high performance thermoplastic polymers with applications ranging from fire-retardants film coatings, packaging, and fibers, resulting from their high thermal and chemical stability. They can be obtained in high yields by copolymerization of inexpensive and readily available feedstocks such as ethylene and carbon monoxide. Our group proved that PK with alternating 1,4-dicarbonyl repeating units constitute an ideal starting point to access a wide class of modified polymers by simple Paal-Knorr cyclization, to gain pyrrole-N-bound functional groups stemming from the aliphatic backbone [4-5].Different ion-conducting membranes have been developed and the effect of reaction conditions on their thermal properties, chemical stability, and their conductivity in a wide range of frequencies have been assessed by broadband electric spectroscopy to shed light on the conduction mechanisms [4, 6]. The more promising material developed has been tested in a single cell redox flow battery obtaining promising results.The proposed conducting polymers combine the thermal stability of the aliphatic PK structure with the chemical flexibility given by the groups derived from functionalized amines branching out, proving to be highly tailorable, with possible applications in current energy conversion technologies. Acknowledgements: The authors wish to thank the Research Projects of Relevant National Interest (PRIN 2017) of the Italian Ministry of Education, University and Research “Novel Multilayered and Micro-Machined Electrode Nano-Architectures for Electrocatalytic Applications (Fuel Cells and Electrolyzers)” (Prot. 2017YH9MRK) and SID2020 Project of Department of Industrial Engineering, University of Padova “A New frontier in Hybrid Inorganic-Organic Membranes for Energy Conversion and Storage Devices” (Prot. BIRD201244) for funding.

Research progress of low dielectric constant polymer materials

Abstract The advent of high frequency communication era presents new challenges for further development of dielectric polymer materials. In the field of communication, efficient signal transmission is critical. The lower the dielectric constant of the dielectric material used, the lower the signal delay and the higher the signal fidelity. The preparation of polymer materials with low dielectric constant or reduce the dielectric constant of polymer materials becomes a key research topic. Summarizing past progress and providing perspective, this paper primarily discusses the intrinsic low dielectric polymers, fluorine doped low dielectric polymers, and microporous low dielectric polymers, while predicting the research trend of low dielectric materials.

Polyketone Functionalization: New Ways to Anion Conducting Polymers

Ion-exchange membranes (IEMs) are at the core of many energy storage and conversion devices, such as fuel cells and redox flow batteries, being responsible for the migration of ionic species, separating the fuel stocks, and providing support to the electrode assemblies. For practical applications they are required to possess not only high ionic conductivity, but also specificity, thermal stability, long lifetime, and electrical insulation. The preparation of polymeric materials with such high-performance properties is still challenging and can lead to high prices, hindering their widespread use in energy conversion technologies. This is even more arduous when considering polymers to be used in anion conducting membranes, due to the need for the extra chemical stability and ability to withstand alkaline conditions at high temperatures for long periods of time [1].Polyketones are known to be high performance thermoplastic polymers with applications ranging from fire-retardants film coatings, packaging, and fibers, resulting from their high thermal and chemical stability. They can be obtained in high yields by copolymerization of inexpensive and readily available feedstocks such as ethylene and carbon monoxide. Our group proved that polyketones with alternating 1,4-dicarbonyl repeating units constitute an ideal starting point to access a wide class of modified polymers by simple Paal-Knorr cyclization, to gain pyrrole-N-bound functional groups stemming from the aliphatic backbone [2].This is a new account on our research on the ion conducting polymeric materials derived from polyketone, obtained by reaction with variously functionalized amines, and their easy conversion to anion exchange materials. The effect of reaction conditions on their thermal properties and chemical stability in alkaline media has been studied, and their conductivity in a wide range of frequencies assessed by broadband electric spectroscopy to shed light on the conduction mechanisms.The proposed conducting polymers combine the thermal stability of the aliphatic polyketone structure with the chemical flexibility given by the groups derived from functionalized amines branching out, proving to be highly tailorable, with possible applications in current energy conversion technologies. Acknowledgements: The authors wish to thank the Research Projects of Relevant National Interest (PRIN 2017) of the Italian Ministry of Education, University and Research “Novel Multilayered and Micro-Machined Electrode Nano-Architectures for Electrocatalytic Applications (Fuel Cells and Electrolyzers)” (Prot. 2017YH9MRK) and the SID2020 Project of the Department of Industrial Engineering, University of Padova “A New frontier in Hybrid Inorganic-Organic Membranes for Energy Conversion and Storage Devices” (Prot. BIRD201244) for funding.

Co-precipitated poly(vinyl alcohol)/chitosan composites with excellent mechanical properties and tunable water-induced shape memory

The preparation of polymeric materials with high performance and functional performance remains a focus of extensive research. In this paper, a good dispersion of regenerated chitosan (RCS) in the poly(vinyl alcohol) (PVA) and a physical cross-linking network of molecular chain entanglements and hydrogen bonding were realized by unique co-precipitation to prepare composites. Dynamic mechanical analysis and tensile tests demonstrated that RCS achieved a significant increase in the mechanical properties. The storage modulus and tensile strength of composites containing 5% RCS were 5205 MPa and 105.7 MPa, which were significantly higher than the 3416 MPa and 60.2 MPa of the pure PVA. Intriguingly, the fabricated PVA/RCS composites exhibited good pH-sensitivity due to internal hydrogen bonding. Moreover, this achieved a tunable water-induced shape memory behavior at different pH environments. This study provides a promising strategy for the use of renewable polysaccharide to achieve high performance and functionality of polymer materials.

Synthesis of highly pure poly(aryleneethnylene)s using palladium supported on calcium carbonate as an eco‐friendly heterogeneous catalyst

ABSTRACTMetal catalyst contamination is a major concern in the preparation of polymeric materials. For conjugate polymers, trace amount of metal catalyst is detrimental to the optoelectronic properties. In this work, a method for synthesizing highly pure fluorescent polymers, poly(aryleneethynylene)s (PAEs), was developed using heterogeneous Pd/CaCO3 catalytic system. Polymerization between a variety of aryl diethynes and aryl diiodides or dibromides were achieved using a catalytic amount of Pd/CaCO3, CuI, and PPh3 at 80 °C in good to excellent yields (79–100%). Resulting polymers possess degree of polymerization ranging from 8 to 50 with polydispersity index of 1.5–3.6. Importantly, PAEs from Pd/CaCO3 catalytic system contain considerably lower level of Pd and Cu contamination (1.9 and 3.4 ppm, respectively) than those obtained from classical homogeneous catalyst, Pd(PPh3)4 and PdCl2(PPh3)2 or heterogeneous catalyst Pd/C. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1556–1563

Sulfur Chemistry in Polymer and Materials Science.

Sulfur and its functional groups are major players in an area of exciting research taking place in modern polymer and materials science, both in academia and industry. In fact, manifold sulfur-based reactions that are both exceptionally versatile as well as tremendously useful have been implemented, and further utilized for the design and preparation of polymeric materials that lead to a plethora of applications ranging from medicine to optics and nanotechnology to separation science. Hence, within this review, an overview of strategies and developments used over the last 5 years to reinforce the importance of the sulfur functional group in modern polymer and materials science is presented. In particular, many important references in the primary literature of sulfur chemistry are referred to, including thiol-ene, thiol-yne, thiol-Michael addition, disulfide cross-linking, and thiol-disulfide exchange, among others, by explaining and illustrating the important principles. Last but not least, the grand aim to underpin the importance of sulfur in modern polymer and materials science is achieved by presenting selected examples in diverse fields and postulating the respective potential for real-world applications.

Establishing optimal conditions for catalytic obtaining of allyl-1,3,4-trimethylcyclohex-3-encarboxylate

Kinetics of the reaction of the catalytic cyclic addition of 2,3-dimethylbuta-1,3-diene and allyl methacrylate by the Diels-Alder reaction was studied. Reaction rate constants k=0.9·10 -3 l/(mol·s) at T=303 K; k=1.6·10 -3 l/(mol·s) at T=313 K; k=2.3·1 -3 l/(mol·s) at T=323 K; k=2.9·10 -3 l/(mole·s at T=333 K and the activation parameters of the reaction E akt =32.6 kJ/mol, ΔS=−203.7 J/(mol·K), ΔH=30.0 kJ/mol were determined. Influence of temperature, molar ratio of reagents and catalyst on the yield of the target product was investigated. At temperature increase from 303 to 333 K, ATMCGC yield increases from 58 % to 76 %. With further increase in temperature, DMB boils and AMA remains in a liquid state, accordingly it is not expected that the target product yield will materially increase. An increase in the excess of DMB:AMA=from 1.5:1 to 4:1 makes it possible to increase yield of ATMCGC from 54 % to 76 %. According to decreasing of the catalytic activity in the reactions of [4+2]-cyclic addition of DMB and esters of acrylic acids, the catalysts are placed in an order: Ag n.p. >Cu 2 Cl 2 >Pd n.p. >Au n.p. . At the established optimal conditions of catalytic production of allyl-1,3,4-trimethylcyclohex-3-enecarboxylate are: temperature of 323−333 K and molar ratio of reagents DMB:AMA=4:1 in the presence of Ag n.p. catalyst (0.25 % mol), the yield of ATMCGC reaches 72−76 % at productivity of 111−117 g/(l/h). Based on the obtained reaction rate constants and the activation parameters of the catalytic [4+2]-cyclic addition of 2,3-dimethylbuta-1,3-diene and allyl methacrylate, it was found that the reaction under study is subject to the kinetic law of the second order. It was established that in the presence of Agn.p. catalyst, the reaction of [4+2]-cyclic addition of 2,3-dimethylbuta-1,3-diene and esters of acrylic acids proceeds through a two-stage mechanism with the initial stage of formation of a catalytic complex which activates the reaction by reducing its energy barrier by 44 kJ/mol. The synthesized alkyl esters of alkylcyclohexenecarbonic acids have the ability of polymerization and can be used as a raw material for preparation of polymeric materials, compositions and hyper plasticizers for concrete mixtures. Polymer compositions made with allyl-1,3,4-trimethylcyclohex-3-enecarboxylate are recommended for manufacture of contact lenses and artificial crystalline lenses

Radical and Atom Transfer Halogenation (RATH): A Facile Route for Chemical and Polymer Functionalization.

This work demonstrates a new halogenation reaction through sequential radical and halogen transfer reactions, named as "radical and atom transfer halogenation" (RATH). Both benzoxazine compounds and poly(2,6-dimethyl-1,4-phenylene oxide) have been demonstrated as active species for RATH. Consequently, the halogenated compound becomes an active initiator of atom transfer radical polymerization. Combination of RATH and sequential ATRP provides an convenient and effective approach to prepare reactive and crosslinkable polymers. The RATH reaction opens a new window both to chemical synthesis and molecular design and preparation of polymeric materials.

Optical control of microphase separation of the photopolymerized composition based on oligo(ester acrylates) for the preparation of polymer materials with the nonuniform nanopore distribution

The possibility of control of microphase separation in the photocured composition bulk with the non-polymerizable component (NC) soluble in the monomer and restrictedly compatible with the polymer was studied for manufacturing polymer materials with the spatially nonuniform nanopore distribution. It is shown by numerical simulation that NC redistribution occurs under the action of radiation with the nonuniform over the surface area intensity distribution in the initial step of photopolymerization when the composition is single-phase. Microphase separation of the composition occurs during polymerization in the regions with an enhanced content of an additive, whereas the composition remains single-phase in the regions with a decreased concentration of NC. After NC removal from the final polymer, a material is obtained in which regions with nanopores and regions of the uniform polymer would coexist. The dependences of the size of these regions on the initial concentration of the neutral component in the composition, diffusion parameters of the polymerized medium, and parameters of actinic radiation were studied. The conclusions of numerical simulation were checked experimentally.

Straightforward synthesis of phosphate functionalized linear polyglycidol

The functionalization of polymers with phosphorus based reagents is of great interest in the preparation of polymeric materials. In this work we present a straightforward method for the introduction of pendant diethyl phosphate groups into polyglycidol by reaction with diethyl chlorophosphate. The degree of functionalization was controlled by the ratio of the phosphorus reagent to the hydroxyl groups attached to the polyether backbone. Resulting polymers were characterized by 1H, 13C, 31P {1H} NMR spectroscopy, FTIR spectroscopy and SEC analysis. The removal of one and both ethyl groups of the phosphate ester was selectively achieved by reaction with sodium iodide or bromotrimethylsilane, respectively.

Research on Preparation and Property of Alternating Multilayer Polymer Electromagnetic Shielding Materials

With the development of materials science and technology, performance and preparation of polymer materials becomes a hot topic. The heat resistance and corrosion resistance of Polymer material are strong and can be manufacture for composite materials. It is widely used in many areas. This paper adds metal shielding materials into polymer materials and uses layered coating technology. This paper treats metal mesh and PET film composite structure as in the electromagnetic shielding layer and prepares the alternating multilayer polymer electromagnetic shielding materials. This paper tests electronic shielding effect of the material. It mainly detects the shielding effect of pass rate, the decay rate, and the electromagnetic intensity of visible light. The result shows that the permeation rate of the materials for visible light is about 40%, and the attenuation effect is 85db. Multilayered metal shielding mesh shields 60% magnetic field strength and obtains good electromagnetic shielding effects. This paper tests the mechanical properties of the material through the polarizing microscope which proves that alternating multilayer polymer material has good continuity mechanical properties and high yield strength and heat resistance. It provides theoretical support for the development of the new type of electromagnetic shielding materials.

Phase field study on the effect of shear flow on polymer phase separation

Shear flow is the main external condition during the preparation of polymer materials. In this paper, microstructural evolution and the size of equilibrium phase during different shear flow in binary polymer systems were investigated via phase field simulation, using Flory-Huggins model and Cahn-Hilliard method. It is found that shear flow greatly affected the microstructure of polymer materials, and anisotropy materials can be prepared by controlling the shear flow.

Novel polymerizable bent‐shaped monomeric molecules

Novel bent‐shaped mesogens based on substituted naphthalene‐2,7‐diol, possessing a double bond at the end of terminal branches, have been synthesized and characterized. A variety of banana‐mesophases has been found, depending on the type of lateral substitution. Increasing the length of the alkyl chain leads to the appearance of the SmCAPA phase for two of the compounds synthesized. Under an electric field a transition into the SmCSPF phase takes place and a tilt angle close to 45° has been found. These materials are appropriate for the preparation of polymeric materials.

A Specific Artificial Antibody toward Mycophenolic Acid Prepared by Molecular Imprinting

Molecular imprinting is the preparation of polymeric materials with specific binding sites for a molecule. A monomer is allowed to interact with the molecule of interest (template) to create low-energy interactions. Polymerization is then induced with a bridging agent and heat or ultraviolet irradiation. During the process of polymerization, the molecule of interest is entrapped within the polymer, which finally can be crushed, sieved, and washed with highly polar solvents to remove the template molecule. The imprint of the template is maintained in the rigid polymer, which is usually made of plastic materials such as acrylics and styrenes. The molecular imprint contains many small crypts with shapes complementary to the interest molecule and which are stabilized by chemical groups oriented during the polymerization process in the presence of the substrate. The imprinted polymer can bind the original molecule with high specificity similar to the specificities observed in enzyme-substrate or antigen-antibody interactions. The high specificity of the binding led to the concept of artificial antibodies (1). The use of artificial antibodies in competitive assays is the most promising application of molecular imprints in clinical chemistry. It has been shown that they can replace monoclonal antibodies from animal origin in certain immunologic assays such as those for cortisol, theophylline, diazepam, morphine, s -propanolol, and methylglucoside (1). Artificial antibodies show numerous advantages compared with natural antibodies:

Electron Beam Technologies for Preparation of Polymeric Materials Used for Waste Water Treatment, Agriculture, and Medicine

Radiation research results in the field of polymeric materials, obtained in the last few years by electron beam irradiation of aqueous solutions containing appropriate monomer mixtures, such as acrylamide, acrylic acid and vinyl acetate, are presented. Two types of polymeric flocculants for waste water treatment and three kinds of hydrogels for agriculture and medicine are described. The effects of radiation absorbed dose, radiation absorbed dose rate, and chemical composition of the irradiated solutions upon the polymeric materials characteristics are discussed. The required absorbed dose levels to produce the polymeric flocculants are in the range of 0.3 to 9 kGy and 4 kGy to 12 kGy for hydrogels. Some experimental results obtained by testing polymeric flocculants with waste water from food industry are given. Polymeric material processing was developed on a pilot plant level with ALID-7 electron linear accelerator of 5.5 MeV and 0.7 kW, built in the Electron Accelerator Laboratory of the Institute of Atomic Physics, Bucharest. A new facility permitting the application of simultaneous electron beam and microwave irradiation is presently under investigation. Preliminary results demonstrated that some polymeric flocculant characteristics, such as linearity, were improved by simultaneous electron beam and microwave treatment. Also, the absorbed dose levels decreased and intrinsic viscosity increased, respectively, by about two times by this new material processing method.

Novel Trends in Ladder Polyheteroarylenes

Abstract Development of several fields of modern engineering has generated a need for the preparation of polymeric materials with working temperatures as high as 300°C. The solution of this problem is largely connected with preparation of new thermally stable polymers. As a consequence, beginning in the middle of the fifties, numerous investigations were carried out in order to obtain new thermally stable macromolecular compounds [1]. These investigations resulted in a considerable number of organo-element [1] and aromatic carbo-chain polymers [1] with a complex of valuable properties; but the chemistry of aromatic polymers containing various heterocycles in the main chains of macromolecules, so-called polyheteroarylenes, has received the most development [1].

Preparation of polymeric materials with semiconductor properties

AbstractThermal treatment of polyacrylonitrile synthesized by means of ionic polymerization, radiation polymerization, or redox initiation yielded substances giving signals in the EPR spectrum and possessing semiconductor properties. From the temperature dependence of the electroconductivity the activation energy was determined, and from the data on the EPR spectra the number of unpaired electrons (1018–5 × 1019/g.) was calculated. The thermoelectromotive force was determined and the existence of a Hall effect established. Addition of copper, iron, and chromium ions to the initial polymer lowers the activation energy and increases the width of the EPR signal. On dehydrobromination of natural rubber bromides and dehydrochlorination of polyvinyl chloride, conjugated double bond polymers were obtained, and their electrical properties were determined. Semiconductor properties were found in condensation products of phthalic anhydride with hydroquinone and the activation energy of these compounds was determined.