Graft Polymerization Research Articles

RAFT Polymerisation by the Radical Decarboxylation of Carboxylic Acids**

AbstractThe controlled grafting of polymers from small‐ and macro‐molecular substrates is an essential process for many advanced polymer applications. This usually requires the pre‐functionalisation of substrates with an appropriate functional group, such as a RAFT agent or ATRP initiator, which requires additional synthetic steps. In this paper, we describe the direct grafting of RAFT polymers from carboxylate containing small molecules and polymers via photochemical radical decarboxylation. This method utilises the innate functional groups present in the substrates, and achieves efficient polymer initiation in a single step with excellent control of molecular weight and dispersity.

Grafting of Polymer Brushes on MOF Surface to Achieve Proton-Conducting Membranes

Grafting of Polymer Brushes on MOF Surface to Achieve Proton-Conducting Membranes

Fabrication of multifunction-integrated adsorbent based on zwitterion functionalized cellulose with high adsorption performance for anionic/cationic dyes and heavy metal ions

A multifunction-integrated adsorbent based on zwitterion functionalized cellulose (MCC@PGMA-IAA) was synthesized by surface grafting polymerization and then modification with polyethyleneimine and sodium chloroacetate in turn. The adsorbent exhibited high functional group contents, switchable surface charge and chelating structure of iminoacetic acid. With the methylene blue, azophloxine, Ni(II) and Cr(VI) as the models of cationic/anionic dyes and heavy metal ions, batch experiments were conducted. The material showed strong adsorption abilities for dyes and heavy metal ions, with maximum adsorption capacities up to 440.5 mg/g, 320.5 mg/g, 59.3 mg/g, and 127.9 mg/g for methylene blue, azophloxine, Ni(II) and Cr(VI), respectively. Especially, the adsorption capacities of methylene blue and Ni(II) after zwitterionic functionalization increased by 50 times and 95.5% than those after polyethyleneimine modification. The adsorption equilibria were achieved within 10–120 min, and the adsorbent exhibited excellent removal efficiency. Furthermore, the adsorbed pollutants were conveniently desorbed by low concentration of HCl or NaOH solution, and the adsorbent had good reusability. Mechanism studies proved that electrostatic attraction and chelation were main driving forces. These results showed that MCC@PGMA-IAA had the characteristics of extensive sources, simple preparation and multifunctional integration, which was poised to develop as universal adsorbent for removing heavy metal ions and dyes.

Preparation and properties of PEEK-g-PNIPAm separation membranes with thermo-responsiveness for emulsion and organic liquid separation

Although poly (ether ether ketone) (PEEK) exhibits excellent solvent resistance, it could not be prepared directly by non-solvent induced phase separation (NIPS) method due to its poor solubility. Herein, PEEK porous membranes were successfully fabricated by combining NIPS and acid hydrolysis. The superhydrophilic thermo-responsive poly (N-isopropylacrylamide) (PNIPAm) polymer was in-situ grafted on the PEEK membrane surface via the UV grafting polymerization and improved the membrane interface hydrophilicity, making the membrane water contact angle changed from 89.5° to 0° at 25 °C. After heating the membrane surface to 40 °C, the membrane exhibited hydrophobicity (100°), realizing the thermo-responsiveness via switching the temperature. Furthermore, due to the transferred membrane wettability at different temperatures, PEEK-g-PNIPAm could separate different types of oil-bearing systems with high rejection above 99.0 %. What’s more, the PNIPAm layer also enhanced the membrane anti-fouling capacity. Benefiting from the extraordinary solvent resistance of the PEEK matrix, PEEK-g-PNIPAm maintains its intact morphology after 6 h immersion in various organic solvents, addressing the commonly reported problem of polymer membranes having certain solubility in solvents. The PEEK-based membranes with excellent solvent resistance could be useful in the oil-bearing separation.

Grafting tetradecyl methacrylate-carbic anhydride (CA) or tetradecyl methacrylate-tetrahydrophthalic anhydride (THPA) co-polymers onto surface-modified nano silica to develop of pour point depressants for diesel

Polymers with alkyl methacrylate as structural unit can significantly improve cold flow properties of diesel. Grafting polymers onto surface-modified nanomaterials can further enhance the low temperature fluidity of diesel. In this study, two molecules containing the structure of dicarboxylic anhydride were used as structural unit with tetradecyl methacrylate to synthesise the polymer pour point depressant (PPD). These polymer PPDs achieved excellent depressive effects, in particular, 1500 ppm of tetradecyl methacrylate–carbic anhydride (9:1) reduced the cold filter plugging point (CFPP) and solid point (SP) of diesel by 8 and 18 ℃, respectively. To further enhance the low-temperature fluidity properties of diesel, silane coupling agents were used to surface-modify nano silica, and then polymers were chemically grafted onto the surface-modified nano silica to prepare the nano PPDs. The well-dispersed nano PDDs achieved higher depressive effects than polymer PPDs on diesel. The diesel treated with 1500 ppm of tetradecyl methacrylate–carbic anhydride–surface modified nano silica (9:1:1) showed a decrease in CFPP and SP of 14 ℃ and 21 ℃, respectively. Transmission electron microscope was used to characterise the morphology and particle size of nano silica before and after surface modification and chemical grafting. The structural features of polymer PPDs and nano PPDs were analysed using fourier transform infrared spectroscopy, gel permeation chromatography and proton nuclear magnetic resonance. Finally, the n-alkane crystallisation habit and wax crystal growth habit of pure diesel and diesel treated with polymer and nano PPDs during cooling process were characterized using differential scanning calorimetry, polarising optical microscopy and rheometry. The effects of polymer and nano PPDs on the nucleation and growth patterns of n-alkanes in diesel were presented and the possible mechanism was inferred.

Synthesis and Application of a Novel Multi-Branched Block Polyether Low-Temperature Demulsifier.

In this paper, a low-temperature thick oil demulsifier with high polarity was prepared by introducing ethylene oxide, propylene oxide block, and butylene oxide using m-diphenol as a starting agent. The main reasons for the difficulty involved in the low-temperature emulsification of extractive fluids were explained by analyzing the synthetic influencing factors and infrared spectra of the star comb polymer (PR-D2) and by analyzing the four fractions, interfacial energies, and zeta potentials of crude oils from the Chun and Gao fields. The effects of PR-D2 surfactant on the emulsification performance of crude oil recovery fluids were investigated via indoor and field experiments. The experimental results indicate that the optimal synthesis conditions for this emulsion breaker are as follows: a quality ratio of ionic reaction intermediates and meso-diphenol of R = 10:1; 1 g of the initiator; a polymerization temperature of 80 °C; and a reaction time of 8 h. Colloidal asphaltenes in the crude oil were the main factor hindering the low-temperature demulsification of the Gao oilfield's extractive fluids, and the reason for the demulsification difficulty of the extractive fluids in the Chun oilfield is that the temperature of demulsification is lower than the wax precipitation point. The demulsification rate of the Chun oilfield's extractive fluids reached more than 98% when the PR-D2 concentration reached 150 mg/L at 43 °C. The demulsification rate of the Gao oilfield's extractive fluids reached more than 98% at a PR-D2 concentration of 150 mg/L at 65 °C. The field experiments show that the Chun oilfield's extractive fluids can still demulsify after the temperature is reduced to 43 °C in winter. The emulsification temperature of the Gao oilfield's extractive fluids was reduced from 73 °C to 68 °C, with an excellent demulsification effect.

Many-body potential for simulating the self-assembly of polymer-grafted nanoparticles in a polymer matrix

Many-body interactions between polymer-grafted nanoparticles (NPs) play a key role in promoting their assembly into low-dimensional structures within polymer melts, even when the particles are spherical and isotropically grafted. However, capturing such interactions in simulations of NP assembly is very challenging because explicit modeling of the polymer grafts and melt chains is highly computationally expensive, even using coarse-grained models. Here, we develop a many-body potential for describing the effective interactions between spherical polymer-grafted NPs in a polymer matrix through a machine-learning approach. The approach involves using permutationally invariant polynomials to fit two- and three-body interactions derived from the potential of mean force calculations. The potential developed here reduces the computational cost by several orders of magnitude, thereby, allowing us to explore assembly behavior over large length and time scales. We show that the potential not only reproduces previously known assembled phases such as 1D strings and 2D hexagonal sheets, which generally cannot be achieved using isotropic two-body potentials, but can also help discover interesting phases such as networks, clusters, and gels. We demonstrate how each of these assembly morphologies intrinsically arises from a competition between two- and three-body interactions. Our approach for deriving many-body effective potentials can be readily extended to other colloidal systems, enabling researchers to make accurate predictions of their behavior and dissect the role of individual interaction energy terms of the overall potential in the observed behavior.

The effects of poly(ethylene glycol) grafting density on the extensional solution flows of high molecular weight polyacrylamide

AbstractControlling the extensional rheological properties of solutions is of great interest for a number of applications, such as printing and coatings, as polymeric additives can modify a fluid's droplet size, formation, and breakup. We have measured the extensional flows of polyacrylamide graft poly(ethylene glycol) amine (PAM‐g‐PEGa) solutions as a function of grafting density. PAM‐g‐PEGa is synthesized with grafting densities of 2.5%, 5.5%, 8%, and 30% and extensional flow was analyzed with drop‐on‐substrate rheology. Flow time scales and profiles are then compared to understand the effects of backbone extension from the addition of side chains. At low grafting densities, the viscous friction from the added side chains is comparable to, and in some cases, counteracts the losses in extensibility to the graft polymer's backbone, leading to increases in the relaxation time of the polymer. At higher grafting densities, the extension of the backbone reduces the relaxation time. By characterizing the effects of the graft density architecture on extensional flows, we are able to fine‐tune and control the breakup dynamics of elastic solutions.

Ultra-thin SiO2 nanoparticle layered separators by a surface multi-functionalization strategy for Li-metal batteries: Highly enhanced Li-dendrite resistance and thermal properties

Mechanical and thermal failure of a polyolefin separator often causes the internal short-circuit of batteries, which leads to abrupt heat generation in a short time, so-called thermal runaway. For this, we introduce grafting polymer layers with cross-linking to make a superior, thin, and uniform SiO2 layer with strong chemical binding to the surface of a polypropylene separator (PPS). The surface of the PPS was modified with i) coating of double bond-contained PVDF, ii) grafting with poly(ethylene glycol) methacrylate, 3-(trimethoxysilyl)propyl methacrylate, and ethylene glycol dimethacrylate, and iii) coating with SiO2 nanoparticles via immersing (GDPS-SNPI) or casting (GDPS-SNPC) methods. The pore structure and distribution, electrolyte affinity, thermal stability, and mechanical properties were progressively improved after respective modification steps. The GDPS-SNPC cell shows excellent capacity retention of 100% at 1 C after 100 cycles and the lowest increase in the cell impedance, whereas the LFP half-cell with PPS exhibited capacity retention of 88.32%. Furthermore, it is found that the coating method for SiO2 nanoparticles substantially influences the long-term cycling stability of Li-symmetric cells. The GDPS-SNPC cell survived after cycling over 1,000 h at a current density of 1 mA cm−2, whereas the GDPS-SNPI cell died before 500 h. Post-mortem analysis of the cycled Li-metal surface shows that smooth Li-plating occurred at the GDPS-SNPC cell, presumably due to a high Li-ion transference number. This work provides a solid methodology for producing a novel and robust separator and advances the understanding of separators' impact on electrochemical and physical phenomena within the cell.

Preparation and catalytic activity evaluation of a novel poly(ionic liquid)-modified silica nanoparticle

In this paper, a novel silica nanoparticle modified with a poly(ionic liquid) is synthesized by an ion exchange reaction and graft polymerization on the surface of the nanoparticle. By utilizing FT-IR, TGA, and TEM, the diverse products prepared are characterized. The modified silica nanoparticles are subsequently used as supporters to generate a catalyst containing Au. To evaluate the catalytic activity of the catalyst, methyl orange is degraded in the presence of H2O2. The results of the experiments indicate the catalyst possesses a level of catalytic activity comparable with that of TiO2 nanoparticles.

Polymer Brushes: Novel Surfaces for Biomedical Applications

Polymer brushes played an important role in surface modification techniques to improve the biocompatibility of modified surfaces inside the human body for different biological and biomedical applications. This modification give the ability to control biointerfacial interactions such as cell attachment, protein adsorption and bacterial biofilm formation. Surface modification with polymer layers can be utilized to alter the surface properties, including biocompatibility, antifouling ability, corrosion resistance and wettability, and it can be achieved by immobilisation or spraying of polymers from solution. Also, it is easy to graft polymers with reactive end groups onto surfaces leading to the formation of polymer brushes at high density, which have specific features, such as chemical robustness, tunable mechanical properties and the flexibility to use polymers of different chemistry or introduction of bifunctional polymers for specific immobilisation of other molecules, especially proteins and enzymes. The specific properties of polymer brushes make them ideal candidates to be used in the biomedical field. For example,

Development and Characterization of Thermoresponsive Smart Self-Adaptive Chitosan-Based Polymer for Wellbore Plugging.

To meet the escalating demand for oil and gas exploration in microporous reservoirs, it has become increasingly crucial to develop high-performance plugging materials. Through free radical grafting polymerization technology, a carboxymethyl chitosan grafted poly (oligoethylene glycol) methyl ether methyl methacrylate acrylic acid copolymer (CCMMA) was successfully synthesized. The resulting CCMMA exhibited thermoresponsive self-assembling behavior. When the temperature was above its lower critical solution temperature (LCST), the nanomicelles began to aggregate, forming mesoporous aggregated structures. Additionally, the electrostatic repulsion of AA chains increased the value of LCST. By precisely adjusting the content of AA, the LCST of CCMMA could be raised from 84.7 to 122.9 °C. The rheology and filtration experiments revealed that when the temperature surpassed the switching point, CCMMA exhibited a noteworthy plugging effect on low-permeability cores. Furthermore, it could be partially released as the temperature decreased, exhibiting temperature-switchable and self-adaptive plugging properties. Meanwhile, CCMMA aggregates retained their reversibility, along with thermal thickening behavior in the pores. However, more detailed experiments and analysis are needed to validate these claims, such as a comprehensive study of the CCMMA copolymer's physical properties, its interaction with the reservoir environment, and its performance under various conditions. Additionally, further studies are required to optimize its synthesis process and improve its efficiency as a plugging material for oil and gas recovery in microporous reservoirs.

Antibacterial Modification of Cotton Fabric Through Argon Plasma-Induced Grafting Polymerization

Antibacterial Modification of Cotton Fabric Through Argon Plasma-Induced Grafting Polymerization

Synthesis and specific biomedical applications of polymer brushes

The modification of surfaces with various polymer chains through interactions involving strong covalent bonds is a current focal point. The relevance of this subject lies in the diversification of polymeric structures, particularly applicable in biomedical engineering and medicine. Presently, designs for drug carrier systems have reached an advanced stage, and novel polymer-based materials have been successfully synthesized. Polymeric brushes find applications in crucial medical areas such as artificial tissue engineering, implants, and biosensors. The advantages of polymeric brushes include their sensitivity to stimuli, a variety of polymer types and synthesis methods, tunability, and high biocompatibility. This study comparatively examines grafting approaches and polymerization techniques frequently encountered in the literature, highlighting their primary medical applications.

ИЗУЧЕНИЕ ГИДРОДИНАМИЧЕСКИХ СВОЙСТВ ХИТОЗАНА В БИНАРНЫХ РАСТВОРАХ УКСУСНАЯ КИСЛОТА-ВОДА

The hydrodynamic properties of chitosan solutions in the acetic acid-water binary system were studied by viscometry and potentiometry methods. The degree of protonation of chitosan macromolecules was determined. The dependence of the degree of chitosan protonation on its concentration in solution and on the acetic acid-water ratio has been established. The obtained results make it possible to formulate optimal conditions for carrying out graft polymerization of chitosan in acetic acid media.

Graft polymerization of methyl methacrylate on the surface of poly(vinylidene fluoride) using tributylborane as an initiator

Graft polymerization of methyl methacrylate on the surface of poly(vinylidene fluoride) using tributylborane as an initiator

40 Years of PCE Superplasticizers ‐ Current State of the Art and Future Perspectives

AbstractWith over 15 Mio tons of annual production, polycarboxylates (PCEs) currently dominate the global superplasticizer market. Among them, HPEG and IPEG PCEs have attained a prominent position as they present the most cost‐effective PCEs known at present. Recently, new vinyl ether PCEs designated as EPEG and GPEG PCEs were introduced, thus broadening the family of VPEG PCEs. Furthermore, novel phosphated comb polymers which significantly reduce the stickiness of concrete have been developed. For calcined clay blended cements, HPEG PCEs of specific molecular design as well as zwitterionic (amphoteric) PCEs have proven to be highly effective. Moreover, NaOH activated AAS binder systems were successfully fluidized with APEG or HPEG PCEs exhibiting particularly short side chains (nEO < 10). While for Na2CO3, Na2SiO3 and Na2SO4 activated systems, the search for effective superplasticizers is still ongoing. This review underlines the critical role which chemical admixtures will play in the successful transition of the construction industry to a net zero carbon age.

Modified abaca fiber prepared by radiation-induced graft polymerization as a reinforcement for unsaturated polyester resin composites

Modified abaca fiber prepared by radiation-induced graft polymerization as a reinforcement for unsaturated polyester resin composites

Reducing residual stress in photopolymerized composites by grafting high-mobility polymer chains onto the filler-matrix interface

3D/4D printing of thermosets, composites and hydrogels, lithographic procedures and dental resins are important examples of applications that rely on light-driven polymerization supported on substrates. Adhesion between the polymer and substrate during photopolymerization (and even between printed layers) can restrict the usual polymerization shrinkage, leading to the generation of residual stresses. These residual stresses can result in poor-quality products due to the presence of cracks and occurrence of warpage. In this work, silica nanoparticles were incorporated into photopolymerizable dimethacrylate based networks. These nanoparticles had their surface modified by grafting polymer chains with high mobility at usual room temperatures (low glass transition temperature polymer) and with high affinity towards the polymer matrix in order to test the hypothesis that these high-mobility chains could be helpful in dissipating stress and energy generated during photopolymerization in conditions in which the polymerization shrinkage is restricted. The nanoparticles and composites were analyzed via: electron microscopy (SEM), thermal analysis and mechanical bending tests. The evolution of the monomer-to-polymer conversion during photopolymerization was monitored using real-time infrared (FTIR) spectroscopy. To determine the residual stress generated by the polymerization at restricted contraction conditions, a universal mechanical testing machine was adapted and used. The results showed that silica nanoparticles with grafted high-mobility polymer chains that were able to interpenetrate and interact with the dimethacrylate based networks led to the production of composites having higher mechanical properties and lower polymerization stresses than composites containing only silanized nanoparticles and nanoparticles having immiscible polymer grafts towards the dimethacrylate based network. Results indicate that the modifications of the interface of composites developed in this work can be useful in the formulation of materials with improved mechanical properties and stability regarding polymerization shrinkage and residual stress that can lead to higher-quality products obtained in processes that employ light-driven polymerization supported on substrates or that occur on sequential polymerized layers, such as 3D/4D printing, lithography and in dental applications.

GFN-xTB-Based Computations Provide Comprehensive Insights into Emulsion Radiation-Induced Graft Polymerization.

In this article, a deep insight into emulsion radiation-induced graft polymerization (RIGP) was obtained by computing explicit solvation free energies, conformational entropy, monomer radius and dipole moments with the state-of-the-art Conformer-Rotamer Ensemble Sampling Tool (CREST) package primarily at semiempirical GFN-xTB level. By leveraging the robustness of the CREST package, above parameters provided dynamic nature of methacrylate monomers with the consideration of realistic emulsion conditions. With the chemical and physical importance of the above results, CREST-determined explanatory variables sufficiently led to the building of the prediction models for the RIGP of methacrylate monomers. The machine learning model building resulted in effective reactivity predictions and unveiled important factors for the radiation-induced graft polymerization in a chemically interpretable fashion.