Different Types Of Monomers Research Articles

Revisiting the Determination of the Degree of Deacetylation Using Potentiometric Titration: A New Equation for Modified Chitosan.

Chitosan is a biopolymer that can be subjected to a variety of chemical modifications to generate new materials. The properties of modified chitosan are affected by its degree of deacetylation (DDA), which corresponds to the percentage of D-glucosamine monomers in its polymeric structure. Potentiometric titration is amongst the simplest, most readily available, and most cost-effective methods of determining the DDA. However, this method often suffers from a lack of precision, especially for modified chitosan resins. This is in large part because the equation used to calculate the DDA does not consider the molecular weight of the chemically modified monomeric units. In this paper, we introduce a new equation that is especially suited for modified chitosan bearing three different types of monomers. To test this equation, we prepared naphthalene-chitosan resins and subjected them to potentiometric titration. Our results show that our new equation, which is truer to the real structure of the polymeric chains, gives higher DDA values than those of the routinely used equations. These results show that the traditional equations underestimate the DDA of modified chitosan resins.

Evaluation of the amount of residual monomer released from different flowable composite resins

Today, resin materials are used in the restoration of permanent and deciduous teeth or as fissure sealants. The materials can contain different types of monomers (Bis-GMA, UDMA, TEGDMA). These monomers can be released into the oral cavity after polymerization. Residual monomers released from resin-containing restorative materials after polymerization have been reported to have negative effects on mechanical properties. The aim of our study is to evaluate the amount of residual monomers released after polymerization of different flowable composite resin materials using two different modes of LED light source. Composite disc samples (8 mm diameter/2 mm depth) prepared for each material group were polymerized using two different modes of the LED light device (Standard mode and extra power mode). HPLC (High Performance Liquid Chromatography) device was used to measure the amount of residual monomer release at 1 h, 1 day, 3 days and 7 days periods. Pairwise comparison of the differences between the materials was performed by Post-hoc test. For each residual monomer, the Kruskal Wallis test was used to analyze the difference between the materials in standard mode and the difference between the materials in extra power mode. According to the results of the study; Grandio flow flowable composite showed the highest release of TEGDMA and Bis-GMA while SDR® Flow flowable composite showed the lowest release of TEGDMA, Bis-GMA and UDMA. For all materials, the extra power mode resulted in more residual monomer release. TEGDMA and Bis-GMA release was detected in all tested flowable composites at all time periods.

Polymeric surfactants at liquid–liquid interfaces: Dependence of structural and thermodynamic properties on copolymer architecture

Polymeric surfactants are amphiphilic molecules with two or more different types of monomers. If one type of monomer interacts favorably with a liquid, and another type of monomer interacts favorably with another, immiscible liquid, then polymeric surfactants adsorb at the interface between the two liquids and reduce the interfacial tension. The effects of polymer architecture on the structural and thermodynamic properties of the liquid–liquid interface are studied using molecular simulations. The interface is modeled with a non-additive binary Lennard-Jones fluid in the two-phase region of the phase diagram. Block and gradient copolymer surfactants are represented with coarse-grained, bead-spring models, where each component of the polymer favors one or the other liquid. Gradient copolymers have a greater concentration at the interface than do block copolymers because the gradient copolymers adopt conformations partially aligned with the interface. The interfacial tension is determined as a function of the surface excess of polymeric surfactant. Gradient copolymers are more potent surfactants than block copolymers because the gradient copolymers cross the dividing surface multiple times, effectively acting as multiple individual surfactants. For a given surface excess, the interfacial tension decreases monotonically when changing from a block to a gradient architecture. The coarse-grained simulations are complemented by all-atom simulations of acrylic-acid/styrene copolymers at the chloroform-water interface, which have been studied in experiments. The agreement between the simulations (both coarse-grained and atomistic) and experiments is shown to be excellent, and the molecular-scale structures identified in the simulations help explain the variation of surfactancy with copolymer architecture.

Threshold of Surface Initiator Concentration for Polymer Brush Growth by Surface-Initiated Atom Transfer Radical Polymerization.

The surface modification of various materials by grafting functional molecules has attracted much attention from fundamental research to practical applications because of its ability to impart various physical and chemical properties to the surfaces. One promising approach is the use of polymer brushes synthesized by atom transfer radical polymerization (ATRP) from surface-tethered initiators (SIs). In this study, for the purpose of controlling the grafting amounts/densities of polymer brushes, we developed a facile method to precisely regulate SI concentrations of SI layers (SILs) by serial dilution based on a sol-gel method. By simply mixing organosilanes terminated with and without an initiator group ((p-chloromethyl) phenyltrimethoxysilane (CMPTMS) and phenyltrimethoxysilane (PTMS), respectively) with tetraethoxysilane (TEOS), SI concentrations of SILs could be arbitrarily tuned precisely by varying dilution factors of (CMPTMS + PTMS)/CMPTMS (DFs, 1-107). The resulting SILs prepared at different DFs were highly smooth and transparent. X-ray photoelectron spectroscopy (XPS) also confirmed that the SIs were homogeneously distributed at the topmost surface of the SILs and their concentrations were proven to be accurately and precisely controlled from high to extremely low, comparable to theoretical values. Subsequent SI-ATRP in air ("paint-on" SI-ATRP) of two different types of monomers (hydrophobic/nonionic (2,3,4,5,6-pentafluorostyrene) and hydrophilic/ionic (sodium 4-styrenesulfonate)) demonstrated that polymer brushes with different grafting amounts/densities were successfully grafted only from SILs with DFs of 1-104 (theoretical SI concentrations: 3.9 × 10-4 ∼ 3.5 units/nm2), while at DFs of 105 and above (theoretical SI concentrations: <3.9 × 10-5 units/nm2), no sign of polymer brush growth was confirmed by thickness, XPS, and water contact angle data. Therefore, we are the first to gather evidence that the approximate threshold of SI concentration required for "paint-on" SI-ATRP might be on the order of 10-4 ∼ 10-5 units/nm2.

Prediction of Serum Adsorption onto Polymer Brush Films by Machine Learning.

Using machine learning based on a random forest (RF) regression algorithm, we attempted to predict the amount of adsorbed serum protein on polymer brush films from the films' physicochemical information and the monomers' chemical structures constituting the films using a RF model. After the training of the RF model using the data of polymer brush films synthesized from five different types of monomers, the model became capable of predicting the amount of adsorbed protein from the chemical structure, physicochemical properties of monomer molecules, and structural parameters (density and thickness of the films). The analysis of the trained RF quantitatively provided the importance of each structural parameter and physicochemical properties of monomers toward serum protein adsorption (SPA). The ranking for the significance of the parameters agrees with our general understanding and perception. Based on the results, we discuss the correlation between brush film's physical properties (such as thickness and density) and SPA and attempt to provide a guideline for the design of antibiofouling polymer brush films.

Development of molecularly imprinted polymer for the selective recognition of the weakly interacting fenamiphos molecule

The possible manufacture of Molecularly Imprinted Polymers (MIPs) under the conditions of weak interaction between the functional monomer and template molecule is addressed with the help of the case of the Fenamiphos organophosphorus insecticide. The choice of the functional monomer is addressed by investigating MIPs prepared by the surface imprinting technique using three very different types of monomers (methacrylic acid, 4-vinylpyridine and 2–(methacryloyloxyethyl)trimethylammonium chloride), a solid silica support grafted with 3-mercaptopropyltrimethoxysilane on its surface; ethylene glycol dimethacrylate as the cross-linker and acetonitrile as solvent. The prepared materials were characterized by IR, solid state 13C NMR, TGA, DLS, BET and TEM. Their performance as adsorbents were evaluated by modeling their experimental adsorption isotherms using the Langmuir–Volmer model. All MIPs show similar adsorbent performance although the functional monomers were quite different and the interactions with fenamiphos were weak. The latter were assessed by 1H and 31P NMR experiments in DMSO‑d6 solution. The adsorption process presented weakly exothermic and endothermic behavior onto molecular imprints and non-specific sites respectively. The selectivity for adsorption of fenamiphos with respect to its sulfone and sulfoxide metabolites was quite high.

Self-Switchable Polymerization: A Smart Approach to Sequence-Controlled Degradable Copolymers

In the quest for sustainable development, degradable polymers are attractive alternatives to traditional fossil-based plastics. As monocomponent degradable polymers often suffer from unsatisfactory performances, the utilization of corresponding copolymers with tailored block compositions is viable for improved properties. To this end, the emerging field of self-switchable polymerization offers a facile access to the on-demand synthesis of degradable copolymers with controlled sequences, in which the polymerizations were regulated by the monomers themselves. This Perspective outlines state-of-the-art self-switchable polymerization systems based on ring-opening (co)polymerization with various types of monomers. The scope of catalysts and monomer types are summarized. Comprehensive comparison between different types of monomers is offered along with an outlook on possible monomers in the future.

Synthesis and Spectroscopic Analyses of New Polycarbonates Based on Bisphenol A-Free Components.

This paper discusses a new synthesis of bisphenol A-free polycarbonates based on four aliphatic–aromatic systems. In the first stage, different types of monomers (with/without sulfur) derived from diphenylmethane were synthesized. Then, new polycarbonates were prepared in the reactions with diphenyl carbonate (DPC) by transesterification and polycondensation reactions. Three different catalysts (zinc acetate, 4-(dimethylamino)pyridine and benzyltriethylammonium chloride) were tested. The structures of the compounds were confirmed by Nuclear Molecular Resonance spectroscopy (NMR) in each stage. The chemical structures of the obtained polycarbonates were verified by means of Attenuated Total Reflectance Fourier Transform infrared spectroscopy (ATR–FTIR). The presence of a carbonyl group in the infrared spectrum confirmed polycarbonate formation. Thermal studies by differential scanning calorimetry (DSC) were carried out to determine the melting temperatures of the monomers. A gel permeation chromatography analysis (GPC) of the polycarbonates was performed in order to investigate their molar masses. Thermal analysis proved the purity of the obtained monomers; the curves showed a characteristic signal of melting. The obtained polycarbonates were characterized as having high resistance to organic solvents, including tetrahydrofuran. The GPC analysis proved their relatively large molar masses and their low dispersity.

Block Copolymer Synthesis by the Combination of Living Cationic Polymerization and Other Polymerization Methods.

The foremost limitation of block copolymer synthesis is to polymerize two or more different types of monomers with different reactivity profiles using a single polymerization technique. Controlled living polymerization techniques play a vital role in the preparation of wide range of block copolymers, thus are revolutionary techniques for polymer industry. Polymers with good control over molecular weight, molecular weight distribution, chain-end functionality and architectures can be prepared by these processes. In order to improve the existing applications and create new opportunities to design a new block copolymer system with improved physical and chemical properties, the combination of two different polymerization techniques have tremendous scope. Such kinds of macromolecules may be attended by combination of homopolymerization of different monomers by post-modification techniques using a macroinitiator or by using a dual initiator which allows the combination of two mechanistically distinct techniques. This review focuses on recent advances in synthesis of block copolymers by combination of living cationic polymerization with other polymerization techniques and click chemistry.

Synthesis and Applications of Polyacrylate based Water White Clear Polymeric Material Fortified with Carbon Nanotubes for Durable

Acrylates are esters of acrylic acid formed by the reaction of acrylic acid with alcohols. These acrylic esters were produced by polymerization of combination with different acrylic monomers to produce the materials with enhanced characteristics for coating applications. The acrylate-based polymers were prepared by varying the nature and ratios of the monomers. Moreover, the properties of the polymeric materials were further improved by compositing with the nano-fillers i.e. carbon nanotubes. Further, the materials were coated on different surfaces to evaluate the coating characteristics by standard analytical procedures. Composition and morphology of the materials were characterized by different spectroscopic techniques. Polyacrylate based polymers were synthesized by step growth polymerization using different types of monomers moieties (5 different types of acrylic monomer along with one functional monomer and an aromatic monomers) to enhance coating properties and to enhance dispersion of carbon nanotubes. Characterization was done by FTIR (Fourier Transform Infra-Red) and UV-Vis spectroscopy. Study of polymeric coating was done on different surfaces by different techniques like Barcol Hardness, Gloss Test, Salt Spray Test, Cross Hatch Test and Mandrel Dent Measurement as given in standard ASTM methods. The results revealed better adhesion, crack resistance, and abrasion resistance. The graphical abstract is given below as Fig-1.

Pemberdayaan masyarakat melalui pelatihan pembuatan ecobrick sebagai upaya mengurangi sampah plastik di Kecamatan Bunga Raya

Plastik adalah bahan sintesis dari hasil polimerisasi berbagai macam monomer. Hampir semua jenis plastik akan melayang ataupun mengapung dalam badan air. Hal ini akan menyebabkan plastik terkoyak-koyak dan terdegradasi oleh sinar matahari, oksidasi dan abrasi mekanik membentuk partikel-partikel plastik. Ecobrick adalah salah satu cara penanganan limbah plastik dengan mengemas plastik yang bersih dan kering ke dalam botol plastik. Pemberdayaan masyarakat untuk mengolah sampah plastik menjadi sesuatu yang berguna dalam jangka waktu yang lama adalah salah satu kunci keberhasilan program daur ulang limbah plastik. Kegiatan pengabdian ini akan memberikan manfaat kepada berbagai pihak, diantaranya bagi peserta pengabdian bagi masyarakat, bagi anggota pelaksana penyuluhan, bagi Perguruan Tinggi dan bagi pemerintah. Khalayak sasaran dalam kegiatan pengabdian ini adalah masyarakat Kampung Bunga Raya Kabupaten Siak. Berdasarkan hasil kegiatan pengabdian kepada masyarakat yang telah dilakukan dapat diketahui bahwa masyarakat sudah bisa membuat tempat duduk dari ecobrick. Dalam kegiatan pengabdian pembuatan ecobrick ini diharapkan masyarakat tidak hanya membuat dalam bentuk kursi-kursi tetapi juga dalam bentuk yang lain. Sehingga bisa dijadikan suatu peluang usaha yang baru bagi masyarakat sasaran.

Tandem Unzipping and Scrambling Reactions for the Synthesis of Alternating Copolymers by the Cationic Ring-Opening Copolymerization of a Cyclic Acetal and a Cyclic Ester.

Cationic copolymerization of different types of monomers, 4-hydroxybutyl vinyl ether (HBVE) and ε-caprolactone (CL), was explored using EtSO3H as an acid catalyst, producing copolymers with a remarkably wide variety of compositions and sequences. In the initial stage of the reaction, HBVE was unexpectedly isomerized to 2-methyl-1,3-dioxepane (MDOP), followed by concurrent copolymerization of MDOP and CL via active chain end and activated monomer mechanisms, respectively. The compositions and sequences of the copolymers were tunable, depending on the initial monomer concentrations. Moreover, a unique method was developed for transforming a copolymer with no CL homosequences into an "alternating" copolymer by removing MDOP from the system using a vacuum pump. This was achieved by the tandem reactions of depolymerization (unzipping) and random transacetalization (scrambling) under thermodynamic control. Specifically, the unzipping of HBVE homosequences proceeded at the oxonium chain end until a nondissociable ester bond emerged next to the chain end, while the scrambling of the main chain via transacetalization transferred midchain HBVE homosequences into the polymer chain end.

Detailed Approach to Investigate Thermodynamically Controlled Supramolecular Copolymerizations.

Elucidating the microstructure of supramolecular copolymers remains challenging, despite the progress in the field of supramolecular polymers. In this work, we present a detailed approach to investigate supramolecular copolymerizations under thermodynamic control. Our approach provides insight into the interactions of different types of monomers and hereby allows elucidating the microstructure of copolymers. We select two monomers that undergo cooperative supramolecular polymerization by way of threefold intermolecular hydrogen bonding in a helical manner, namely, benzene-1,3,5-tricarboxamide (BTA) and benzene-1,3,5-tris(carbothioamide) (thioBTA). Two enantiomeric forms and an achiral analogue of BTA and thioBTA are synthesized and their homo- and copolymerizations are studied using light scattering techniques, infrared, ultraviolet, and circular dichroism spectroscopy. After quantifying the thermodynamic parameters describing the homopolymerizations, we outline a method to follow the self-assembly of thioBTA derivatives in the copolymerization with BTA, which involves monitoring a characteristic spectroscopic signature as a function of temperature and relative concentration. Using modified types of sergeants-and-soldiers and majority-rules experiments, we obtain insights into the degree of aggregation and the net helicity. In addition, we apply a theoretical model of supramolecular copolymerization to substantiate the experimental results. We find that the model describes the two-component system well and allows deriving the hetero-interaction energies. The interactions between the same kinds of monomers (BTA–BTA and thioBTA–thioBTA) are slightly more favorable than those between different monomers (BTA–thioBTA), corresponding to a nearly random copolymerization. Finally, to study the interactions of the monomers at the molecular level, we perform density functional theory-based computations. The results corroborate that the two-component system exhibits a random distribution of the two monomer units along the copolymer chain.

Development of Tailor-Made Superabsorbent Polymers: Review of Key Aspects from Raw Material to Kinetic Model

The ability of superabsorbent polymers (SAP) to absorb and retain a large amount of water and/or aqueous solution enables their applications in areas such as agriculture, medicine and water treatment. This versatility has attracted the attention of researchers interested in developing new materials, especially bio-based polymers. As a result, there are numerous studies reporting different types of monomers and crosslinks to produce SAP. Conversely, in the literature there is a lack of discussion of the modeling approaches to describe SAP production. This paper makes a comprehensive and systematic review of the main issues for the synthesis of new SAP materials: monomer and crosslink types, as well as the kinetic model. A database on the raw materials to produce SAP for the main applications should be useful for those interested in producing new SAP materials. The mathematical model correlates structural properties with the synthesis conditions, thus supporting the development of tailor-made products.

Modeling and process optimization of a full-scale emulsion polymerization reactor

One of the most common but promising processes for the production of paints and coatings is the free radical emulsion polymerization reaction involving different types of monomers. As it is also demonstrated by statistics concerning accidents in chemical industries, polymerizations are one of the most frequent causes of thermal runaway; therefore such syntheses require a very high level of control of all the operating variables, especially at full plant scale where safety problems are of paramount importance.The main aims of this work were the modeling and the industrial scale optimization of a complex polymerization process. Since four different monomers are involved in different proportions in such a process, the pseudo-homopolymer approach together with available literature correlations for the estimation of the main constitutive parameters of the system were used to solve the mathematical model and simulate the dynamics of the synthesis at the full plant scale.The proposed model and all the constitutive parameters estimates were validated through the comparison with both laboratory and full-scale experimental data, demonstrating a good agreement. Finally, the results of the optimization procedure were validated at laboratory scale.

Characterization of Mechanical Property Change in Polymer Aerogels Depending on the Ligand Structure of Acrylate Monomer

In an effort to overcome the weakness of aerogel, polymer aerogels have been prepared by copolymerizing the different types of monomers through sol-gel process. Polymerizing the successive phase of a high internal phase emulsion, which has interconnected porous structure, porous polymer aerogel can be manufactured. In this paper, we use the styrene/divinylbenzene chain as a basic monomer structure, and additionally use 2-ethylhexyl methacrylate (2-EHMA) or 2-ethylhexyl acrylate (2-EHA) as monomers for distinguishing the visible mechanical properties of synthesized polymer aerogel. We can observe the different tendency of polymer aerogels by kinds of monomer or ratio. Flexibility and microstructure can be changed by the types of monomer. EHA polymer aerogel shows high flexibility and thin microstructure, and EHMA polymer aerogel shows high hardness and thick microstructure. EHA/EHMA polymer aerogel shows the intermediate nature between them. By utilizing the mechanical properties of three types of polymer aerogels to adequate situation or environment, polymer aerogels could be used as drug agent, ion exchange resin, oil filter and insulator, and so on.

Controlled Cationic Copolymerization of Vinyl Monomers and Cyclic Acetals via Concurrent Vinyl-Addition and Ring-Opening Mechanisms

Vinyl monomers and cyclic acetals were demonstrated to copolymerize with sufficient crossover propagation reactions in a controlled manner via the generation of long-lived species. Such unusual propagation reactions, mediated by the active species derived from different types of monomers, were shown to require an appropriate dormant–active equilibrium, achieved via the elaborate design of the initiating systems. The controlled copolymerization of 2-chloroethyl vinyl ether (CEVE) and 1,3-dioxepane (DOP) proceeded using SnCl4 as a catalyst in conjunction with ethyl acetate and 2,6-di-tert-butylpyridine, yielding multiblock-like copolymers as a result of several rounds of crossover reactions per chain. Under the same conditions, when 2-methyl-1,3-dioxolane (MDOL) was used instead of DOP, the polymerization proceeded in a highly controlled manner and involved more frequent crossover reactions. In addition, MDOL underwent almost no homopropagation reactions, unlike DOP. The nature of the cyclic acetal-derived ...

Possibilities of 3D printer Rapidshape D30 for manufacturing of cubic samples

The purpose of the present paper is to establish experimentally the possibilities of the 3D printer Rapidshape D30 for the manufacturing of standard cubic samples from different types of monomers and to evaluate their geometrical accuracy and roughness. Standard cubic samples with dimensions 5mm х 5mm х 5mm were printed from all the materials, given by the producer, in two ways of dimensional orientation according to the base – horizontally and inclined at 45о. They were manufactured with 3D printer Rapidshape D30, working on a stereolithography principle with LED light. It was established that: ❖❖ The samples, made of NextDent Surgical Guide, have the highest dimensional accuracy and the lowest deviation interval in both ways of placement. This polymer is characterized with the highest thickness of the polymerization layer – 0.100 mm, but it is transparent, thus ensuring the entire polymerization throughout the depth of the whole layer. NextDent C+B, intended for manufacturing of temporary crowns and bridges, occupies a middle position in comparison to the other 6 materials. ❖❖ Nearly in all the materials the surface roughness of the cube with horizontal placement is lower than that of the cube printed inclined (average values of Ra 0.46-2.69μm and Ra 1.74-2.77, respectively). ❖❖ In 3D printing the surface roughness depends on the thickness of the polymerization layer and the inclination to the printing direction. The thicker the polymerization layer and the larger the slope, the higher the surface roughness.

Concurrent cationic vinyl-addition and ring-opening copolymerization of vinyl ethers and oxiranes

Our recent results in the concurrent cationic vinyl-addition and ring-opening copolymerization of vinyl ethers (VEs) and oxiranes are summarized with particular emphasis on the strategies required to generate crossover reactions between different types of monomers. Most importantly, carbocation generation via the ring-opening reaction of the oxonium ion is indispensable for the crossover reaction from oxirane to VE. This article also summarizes concurrent cationic vinyl-addition, ring-opening and carbonyl-addition terpolymerization, the copolymerization using an alkoxyoxirane through the alkoxy group transfer mechanism and the long-lived species-mediated polymerization using cyclic formals.

Optical and thermal properties of PTh-co-PANI-Ti random copolymer composite for photovoltaic application

In thе present work, a polythiophene (PTh)-co-polyaniline (PANI)-titanium (Ti) copolymer has been synthesized as a novel copolymeric composite material for photovoltaic (PV) application. The focus of the study was to evaluate optical and thermal properties of the PTh-co-PANI-Ti copolymer containing different types of monomers. The optical conductivity was determined from the UV–VIS spectra that were used to calculate the extinction coefficients. The structure and morphology of composite was analyzed through field emission-electron microscopy (FESEM). The PTh-co-PANI-Ti copolymer composite exhibited significant photovoltaic (PV) response to light intensity. J–V analysis showed an increase in conversion efficiency from 0.21 to 1.5 of PTh-co-PANi-Ti with illumination light intensity. PV properties demonstrated that the PTh-co-PANI-Ti exhibited the highest power conversion efficiency ɳ=1.5, with a short circuit current Isc=0.72mA, an open circuit voltage Voc=0.9V and a fill factor FF=0.51. Thermo-gravimetric (TG) and differential thermal (DTA) analyses were carried out for the thermal stability of the PTh-co-PANI-Ti copolymer composite. The results obtained from the characterization of PTh-co-PANI-Ti showed that many properties of PV action are present in as-synthesized material.