Copolymerization Of Methyl Methacrylate Research Articles

2D ZIF-L(Zn) for Hybrid Copolymerization of Methyl Methacrylate and ε-Caprolactone under Solvent-free Medium

Herein, we report the hybrid copolymerization of methyl methacrylate (MMA) and ε-caprolactone (CL). 2D metal-organic frameworks, ZIF-L as a robust polymerization catalyst, can catalyze this hybrid copolymerization. Though these monomers differ from each other in structure and activity, different characterization techniques (1H-NMR, 13C-NMR, GPC, DSC, fractional precipitation techniques) confirm that they form biodegradable block copolymer PMMA-b-PCL with high molecular weight (1190 kg/mol). Also, PXRD and SEM results of the recovered ZIF-L reveal that the catalyst ZIF-L is remarkably stable even after a long-time polymerization reaction with no significant loss in activity.

PH-Sensitive Acrylic Terpolymers for the Coating of Orally Administered Drugs Used for Colonic Release.

Polymeric coatings are a promising option for the development of delivery systems for orally administered drugs. However, the gastrointestinal conditions to which they are subjected, which include low pH and solubility as well as peristaltic movements, can limit their applications. In this work, different formulations of polymeric coatings were produced using pH-sensitive materials consisting of copolymers of methyl acrylate, methyl methacrylate, and methacrylic acid. The polymers were synthesized by the emulsion polymerization technique, obtaining small average particle sizes (56-190 nm), molecular weights between 200,000 and 400,000 g/mol, and a glass transition temperature above 35 °C, which are suitable for film formation at room temperature. Thus, they were assessed as coatings for hydroxypropyl methylcellulose capsules (HPMC) using the immersion method, showing adequate capacity to protect the capsule at gastric pH (pH 1.2) and dissolve at the simulated intestinal pH (pH= 7.2). In particular, the higher the content of the acidic monomer, the higher the release time of the test molecule contained in the acrylic terpolymer-coated HPMC capsules proposed, which was a curcuminoid derivative due to their bright color and potential medical benefits. In addition, a minimum number of immersions was required for coating the HPMC capsules at high acidic concentrations, which further facilitates the delayed release needed for colonic treatment. However, too high proportions of methacrylic acid may result in cytotoxicity issues. Consequently, a biocompatible formulation containing a proportion of methyl acrylate, methyl methacrylate, and methacrylic acid of 7:3:3 is proposed as the most adequate for colonic release. Thus, by chemically modulating the molar percentages of the acrylic monomers, it was possible to obtain tailored acrylic terpolymer coatings with different characteristics and desired properties in order to modulate the release kinetics of an active substance in a colonic environment.

Synthesis and characterization of PMMA-grafted-ZrO2 hybrid nanoparticles

In this study, we reported a facile synthesis and the characterization of PMMA-grafted ZrO2 hybrid nanoparticles from original ZrO2 (oZrO2) nanoparticles. The synthesis process included of three steps: (i) modification of nano ZrO2 with a vinyl silane agent, (ii) graft copolymerization of methyl methacrylate (MMA) monomers and modified ZrO2 (mZrO2) nanoparticles, and (iii) extraction of homo PMMA to obtain the final product of PMMA-g-ZrO2 (gZrO2) nanoparticles. Fourier transform infrared (FTIR) spectra and thermogravimetric analysis (TGA) of mZrO2, oZrO2, and gZrO2 indicated that the silane coupling agent was grafted onto oZrO2 nanoparticles. FTIR spectra of gZrO2 indicated PMMA had been successfully grafted onto the surface of ZrO2 nanoparticles. Using TGA method, the PMMA grafting content onto ZrO2 nanoparticles was evaluated as 9.03 wt.%. The electron microscopy (SEM) images of gZrO2, mZrO2, and oZrO2 indicated that their primary particle size and shape were almost unchanged after modification processes, their particle size was in the range from 50 nm to 140 nm. XRD analysis showed the monoclinic crystalline structure of three kinds of ZrO2 nanoparticles (nanocrystals). The organic gZrO2 nanoparticles can be a better candidate as an opacifier additive for polymer nanocomposites or acrylic bone cement.

A stable metal ferrite Construction, physical Characterizations, and investigation magnetic properties in thin polymer films

A stable nickel ferrite (NiFe2O4) was constructed as incorporated into starch grafted acrylic acid copolymer matrix by co-precipitations followed by annealing. A sample, as annealed at temperature 600 °C, yields a NiFe2O4 of tailored the magnetic properties. The structural, morphological and magnetic properties were investigated by XRD, FTIR, SEM and VSM characterizations. SEM and XRD analysis indicate that particle size in the nano range. In-situ polymerization process was used to insert prepared material with acceptable surface morphology into a starch-grafted methyl methacrylate copolymer. By using FTIR and VSM to assess the magnetic characteristics, nanocomposite was created in this manner was evaluated. Magnetic properties of (NiFe2O4) arise with saturation magnetization Ms = 19 emµg−1. Studies made at room temperature reveals the soft nature of synthesized ferrites. These approaches outcomes demonstrated the material value as a biodegradable thin film with tunable magnetic characteristics that may be used as magnetic strips in future.

Attapulgite and Graphene‐Based Molecular Imprinted Polymers as 5‐FU Delivery Systems for the Treatment of Cervical Cancer**

AbstractMolecularly imprinted polymers and non‐imprinted polymers based on attapulgite and graphene composite were synthesized by coating with copolymer of acrylamide and methyl methacrylate. The adsorption results showed that the molecularly imprinted polymers and non‐imprinted polymers could reach the maximum drug loading of 2.4 and 1.6 mg/g, respectively. The in vitro release studies demonstrated that molecularly imprinted polymers and non‐imprinted polymers can control the release of 5‐fluorouracil and reach maximum release at approximately 48 h. Cytotoxicity analysis showed that 100 μg/mL of molecularly imprinted polymers loaded with 5‐fluorouracil gradually increased the inhibition rate of HeLa with increasing time and approached the maximum inhibition rate of 20 % at 72 h.

Chameleon-like Photoluminescent Janus Nanoparticles as Full-Color Multicomponent Organic Nanoinks: Combination of Förster Resonance Energy Transfer and Photochromism for Encryption and Anticounterfeiting with Multilevel Authentication.

Increasing the security by the multilevel authentication mechanism was the most significant challenge in recent years for the development of anticounterfeiting inks based on photoluminescent nanomaterials. For this purpose, the greatest strategy is the use of multicomponent organic materials and a combination of Förster resonance energy transfer (FRET) with the intelligent behavior of photochromic compounds like spiropyran. Here, the hydroxyl-functionalized polymer nanoparticles were synthesized by emulsion copolymerization of methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA) in different compositions (0-30 wt % of HEMA). Results illustrated that the size of the nanoparticles changed from 64 to 204 nm, and a morphology evolution from spherical to Janus shape was observed by increasing the concentration of HEMA. Photoluminescent inks with red, green, and blue (RGB) fluorescence emissions were prepared by modification of nanoparticles containing 15 wt % of HEMA with spiropyran, fluorescein, and coumarin, respectively. To develop dual-color and multicolor photoluminescent inks that display static and dynamic emission, RGB latex samples were mixed together in different ratios and printed on cellulosic paper. Results display that the fluorescence emission of developed inks can be photoswitched between different statuses, including white to blue, green to blue, green to red/orange, purple to pink, and white to pink, utilizing the FRET phenomenon, photochromism, and a combination of both phenomena. Samples containing spiropyran displayed dynamic color changes in the emission to red, orange, and pink depending on the composition. Hence, developed dual-color and multicolor photoluminescent inks were used for printing of security tags and also painting of some hand-drawn artworks, which obtained results indicating high printability, maximum fluorescence intensity, high resolution, and fast responsivity upon UV-light irradiations of 254 nm (for static mode) and 365 nm (for dynamic mode). In addition, the multilevel authentication mechanism by a static emission under UV-light irradiation of 254 nm, a dynamic emission under UV-light irradiation of 365 nm, and photochromic color change was observed, resulting in increasing the security of developed inks. Actually, developed multicolor photoluminescent inks are the most efficient candidates for developing a new category of chameleon-like high-security anticounterfeiting inks that have tunable optical properties and complex multilevel authentication mechanisms.

Poly(methyl methacrylate‐co‐butyl acrylate) copolymer/Ag nanocomposites prepared by latex mixing for multifunctional coatings

AbstractInspired by mussel chemistry, we presented a facile and eco‐friendly method to synthesize silver nanoparticles (AgNPs) using dopamine as a reductant and stabilizer. The synthesized AgNPs as an antibacterial agent and photothermal filler were further introduced to random copolymers of methyl methacrylate and butyl acrylate (MMA‐co‐BA) via latex mixing. The morphology and structure of the formed AgNPs were confirmed by transmission electron microscopy (TEM), UV–Vis spectrum, and x‐ray powder diffraction (XRD). The results showed that the synthesized AgNPs were spherical in the size of 5–30 nm with the characteristic crystalline structure of AgNPs. Mechanical properties of MMA‐co‐BA were significantly enhanced by the introduction of AgNPs. The MMA‐co‐BA/Ag nanocomposite films showed antibacterial activity against E. coli and S. aureus. Moreover, the scratches on the MMA‐co‐BA/Ag nanocomposite film can be healed under infrared light irradiation, which indicated that AgNPs enhanced the self‐healing ability of the MMA‐co‐BA. This work offers a viable avenue for developing antibacterial activity and self‐healing multifunctional coatings.Highlights Silver nanoparticles modified by dopamine are introduced to acrylic copolymer. Acrylic copolymer/Ag nanocomposites exhibit antibacterial activity. Acrylic copolymer/Ag nanocomposites have photothermal performance. Acrylic copolymer/Ag nanocomposites have self‐healing ability.

Capturing Acidic CO2 Using Surface-Active Difunctional Core-Shell Composite Polymer Particles via an Aqueous Medium.

Multifunctional surface-active polymeric composites are attractive materials for the adsorption of various small molecules. Herein, dual-functionalized micron-sized surface-active composite polymer particles were prepared by a three-step process for CO2 adsorption. First, polystyrene (PS) seed particles were prepared via the dispersion polymerization of styrene. PS/P(MMA-AAm-EGDMA) composite polymer particles were then synthesized by aqueous seeded copolymerization of methyl methacrylate (MMA) and acrylamide (AAm) in the presence of an ethylene glycol dimethacrylate (EGDMA) cross-linker. Finally, the amide moieties of PS/P(MMA-AAm-EGDMA) composite particles were converted into an amine-functionalized composite by using the Hofmann degradation reaction. The presence of primary amine groups on the surface of aminated composite particles was confirmed by some conventional chemical routes, such as diazotization and Schiff's base formation reactions. The formation and functionality of the PS seed, PS/P(MMA-AAm-EGDMA), and aminated PS/P(MMA-AAm-EGDMA) composite polymer particles were confirmed by Fourier transform infrared (FTIR) spectra analyses. Scanning electron microscopy (SEM) analysis revealed spherical shape, size, and surface morphologies of the PS seed, reference composite, and aminated composites. The elemental surface compositions, surface porosity, pore volume, pore diameter, and surface area of both composite particles were evaluated by energy-dispersive X-ray (EDX) mapping, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) analyses. Dynamic light scattering (DLS) and ζ-potential measurements confirmed the pH-dependent surface properties of the functionalized particles. The amount of the adsorbed anionic emulsifier, sodium dodecyl sulfate (SDS), on the surface of aminated PS/P(MMA-AAm-EGDMA) is higher at pH 4 than that at pH 10. A vice versa result was found in the case of cationic surfactant, hexadecyltrimethylammonium bromide (HTABr), adsorption. Synthesized aminated composite particles were used as an adsorbent for CO2 adsorption via bubbling CO2 in an aqueous medium. The changes in dispersion pH were monitored continuously during the adsorption of CO2 under various conditions. The amount of CO2 adsorption by aminated composite particles was found to be 209 mg/g, which is almost double that of reference composite particles.

Cationic β‐Scission of C−H and C−C Bonds for Selective Dimerization and Subsequent Sulfur‐Free RAFT Polymerization of α‐Methylstyrene and Isobutylene

AbstractA series of exo‐olefin compounds ((CH3)2C(PhY)−CH2C(=CH2)PhY) were prepared by selective cationic dimerization of α‐methylstyrene (αMS) derivatives (CH2=C(CH3)PhY) with p‐toluenesulfonic acid (TsOH) via β‐C−H scission. They were subsequently used as reversible chain transfer agents for sulfur‐free cationic RAFT polymerization of αMS via β‐C−C scission in the presence of Lewis acid catalysts such as SnCl4. In particular, exo‐olefin compounds with electron‐donating substituents, such as a 4‐MeO group (Y) on the aromatic ring, worked as efficient cationic RAFT agents for αMS to produce poly(αMS) with controlled molecular weights and exo‐olefin terminals. Other exo‐olefin compounds (R−CH2C(=CH2)(4‐MeOPh)) with various R groups were prepared by different methods to examine the effects of R groups on the cationic RAFT polymerization. A sulfur‐free cationic RAFT polymerization also proceeded for isobutylene (IB) with the exo‐olefin αMS dimer ((CH3)2C(Ph)−CH2C(=CH2)Ph). Furthermore, telechelic poly(IB) with exo‐olefins at both terminals was obtained with a bifunctional RAFT agent containing two exo‐olefins. Finally, block copolymers of αMS and methyl methacrylate (MMA) were prepared via mechanistic transformation from cationic to radical RAFT polymerization using exo‐olefin terminals containing 4‐MeOPh groups as common sulfur‐free RAFT groups for both cationic and radical polymerizations.

Cationic β-Scission of C-H and C--C Bonds for Selective Dimerization and Subsequent Sulfur-Free RAFT Polymerization of α-Methylstyrene and Isobutylene.

A series of exo-olefin compounds ((CH3)2C(PhY)-CH2C(=CH2)PhY) were prepared by selective cationic dimerization of α-methylstyrene (αMS) derivatives (CH2=C(CH3)PhY) with p-toluenesulfonic acid (TsOH) via β-C-H scision. They were subsequently used as reversible chain transfer agents for sulfur-free cationic RAFT polymerization of αMS via β-C-C scission in the presence of Lewis acid catalysts such as SnCl4. In particular, exo-olefin compounds with electron-donating substituents, such as a 4-MeO group (Y) on the aromatic ring, worked as efficient cationic RAFT agents for αMS to produce poly(αMS) with controlled molecular weights and exo-olefin terminals. Other exo-olefin compounds (R-CH2C(=CH2)(4-MeOPh)) with various R groups were prepared by different methods to examine the effects of R groups on the cationic RAFT polymerization. A sulfur-free cationic RAFT polymerization also proceeded for isobutylene (IB) with the exo-olefin αMS dimer ((CH3)2C(Ph)-CH2C(=CH2)Ph). Furthermore, telechelic poly(IB) with exo-olefins at both terminals was obtained with a bifunctional RAFT agent containing two exo-olefins. Finally, block copolymers of αMS and MMA were prepared via mechanistic transformation from cationic to radical RAFT polymerization using exo-olefin terminals containing 4-MeOPh groups as common sulfur-free RAFT groups for both cationic and radical polymerizations.

Residue-free and nondestructive separation of transparent adhesive thin films using the interfacial coating of thermo-responsive nanocapsules

The effective separation of flexible optoelectronic panels bonded with transparent adhesive films is an innovative technology that enables the reuse of expensive devices, reducing manufacturing costs in multilayered flexible displays. Herein, we present an effective, facile strategy for heat-triggered detachment of adhesive thin films with high optical transparency by interfacial coating with thermo-responsive nanocapsules. These temperature-sensitive nanocapsules, comprising reactive benzenesulfonyl hydrazide cores and polyacrylonitrile-poly(methyl methacrylate) copolymer shells, were simply prepared through a one-pot synthesis using surfactant-free emulsion polymerization. The synthesized nanocapsules were mixed with UV-curable resins and applied as a thin interfacial layer on the substrate through blade coating and UV curing, producing a transparent, uniform nanocapsule layer of 10 μm with extensive coverage. A transparent double-layered adhesive film was achieved by stacking optically clear adhesive film on the interfacial nanocapsule layer. Compared with pure transparent adhesive film, this double-layered adhesive film containing interfacial nanocapsule layer yields a remarkable optical transparency of 99.1 % and high initial adhesion strength of 98.2 %. Furthermore, a short-time heat treatment at 100 °C produces numerous gas microbubbles in the interfacial region between the substrate and optical thin film, facilitating their clean and spontaneous detachment with an outstanding desorption efficiency of 78.7 %. Our separation approach will be helpful for providing a promising way to dismantle polymer thin films without surface damage in wide industries from semiconductor packaging to flexible devices.

Synthesis and Characterization of a Poly (methyl methacrylate-co-N-(2,9- dimethyl-1,10-phenantrolin-5-yl) acrylamide) Copolymer. Preliminary Results of its Interaction with some Lanthanides in in Acid Media

In this work, we synthesized a copolymer of methylmethacrylate with a monomer derived from 2,9-dimethyl-1,10-phenanthroline, in order to be tested for lanthanide uptake and possible nuclear fuel reprocessing. The incorporation of this monomer in the copolymer was confirmed by the observed results on the 1H NMR, which also allowed us to estimate the molar composition of these material. We found that feed composition does not correlate with the composition of the copolymer, which is attributed to a tendency to a preferential incorporation of methylmethacrylate instead the phenanthroline monomer by the growing chain. This behavior would indicate that methylmethacrylate have a higher reactivity, probably attributed to a steric hindrance exerted by the neocuproyl group. The copolymer is stable up to 300 °C. Using ICP we were able to determine that poly(methylmethacrylate-co-N-(2,9-dimethyl-1,10-phenantrolin-5-yl)acrylamide)) shows a marginal retention of rare earth cation at the working low pH, probably due to an unfavorable spatial arrangement of the pendant aromatic groups.

The Design and Preparation of Antibacterial Polymer Brushes with Phthalocyanine Pigments

Phthalocyanine pigments have many problems in waterborne coating applications because of their low polarity, poor dispersion in water, and easy agglomeration properties. In order to solve these problems, the phthalocyanine pigments were encapsulated with a copolymer of methyl methacrylate (MMA) and butyl acrylate (BA) by a mini-emulsion polymerization method. The pigments are effectively dispersed in water and have good compatibility with the resin. Concerning the bacterial reproduction and growth problem for the waterborne system, the resin-encapsulated phthalocyanine pigments were further grafted with antibacterial polymer poly(N-(2-hydroxyethyl) acrylamide) (PHEAA) on its surface using the photoemulsion polymerization technique. Comprehensive properties, including centrifugal stability and chromaticity change, were studied. The polymer encapsulation improved the centrifugal stability of the pigment. The thermogravimetric results showed that the residual mass of C.I. Pigment Green 7 (52.30%) was higher than that of C.I. Pigment Blue 15:3 (30.06%), and the sublimation fastness of PG7 was higher. The TEM results revealed that the shape of the PG7 after encapsulation and grafting was more regular than that of PB15:3. The L* of the pigment decreased after encapsulation but then increased after further grafting. The phthalocyanine pigment composite latex had good antibacterial properties after the grafting of PHEAA.

Synthesis of acrylic resin and methacrylic resin microspheres by suspension polymerization.

The process of suspension polymerization was utilized to create acrylate resin microspheres with mesh numbers of 140-200μm and particle sizes of 100μm for implementation in mesh coating technology. The copolymer of methyl methacrylate (MMA) and methyl acrylate (MA) served as the primary polymer, with dibenzoyl peroxide (DBPO) functioning as the initiator, and a mixture of calcium carbonate and deionized water served as the dispersion medium. The surface morphology of the synthesized microspheres was analyzed through Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) to confirm successful synthesis. The optimal reaction conditions for the synthesis of these microspheres were determined to be a dispersant dosage of 30g of calcium carbonate with a monomer ratio of 4:1, a reaction time of 1h, an initiator dosage of 1.2g of BPO, and a reaction temperature of approximately 75-80C, resulting in microspheres with a regular spherical shape and smooth surface.

Scaffold Chemical Model Based on Collagen-Methyl Methacrylate Graft Copolymers.

Polymerization of methyl methacrylate (MMA) in aqueous collagen (Col) dispersion was studied in the presence of tributylborane (TBB) and p-quinone: 2,5-di-tert-butyl-p-benzoquinone (2,5-DTBQ), p-benzoquinone (BQ), duroquinone (DQ), and p-naphthoquinone (NQ). It was found that this system leads to the formation of a grafted cross-linked copolymer. The inhibitory effect of p-quinone determines the amount of unreacted monomer, homopolymer, and percentage of grafted poly(methyl methacrylate) (PMMA). The synthesis combines two approaches to form a grafted copolymer with a cross-linked structure-"grafting to" and "grafting from". The resulting products exhibit biodegradation under the action of enzymes, do not have toxicity, and demonstrate a stimulating effect on cell growth. At the same time, the denaturation of collagen occurring at elevated temperatures does not impair the characteristics of copolymers. These results allow us to present the research as a scaffold chemical model. Comparison of the properties of the obtained copolymers helps to determine the optimal method for the synthesis of scaffold precursors-synthesis of a collagen and poly(methyl methacrylate) copolymer at 60 °C in a 1% acetic acid dispersion of fish collagen with a mass ratio of the components collagen:MMA:TBB:2,5-DTBQ equal to 1:1:0.015:0.25.

Random and block architectures of N-arylitaconimide monomers with methyl methacrylate

Abstract “Itaconimide” is the members of imide (–CO–NH–CO–) family with reactive exocyclic double bond and it is easily obtained from the renewable resource i.e. D-glucose. The polymerization of various N-arylitaconimide (NAI) monomers with methyl methacrylate (MMA) have been reported to improve the glass transition temperature (T g) and thermal stability of poly(methyl methacrylate) (PMMA). In literature, these studies have been done mostly using conventional free radical polymerization methods, which restricts the architecture of copolymers to “random” only. The block copolymers of NAI and MMA are an important due to the combination of glassy PMMA and thermally stable poly(NAI), which offers its applications for higher temperature service. The architectural control of polymers in provisions of its topology, composition, and various functionalities is possibly obtained using reversible-deactivation radical polymerizations (RDRPs). In RDRPs, the concentration of free radical is controlled in such a way that the termination reactions are minimized (normally in range of 1–10 mol%), and not allowed to obstruct with the desired architecture. However, this is possible by achieving (or by establishing) a rapid dynamic equilibrium between propagating radical and dormant species (i.e. R–X). Among all RDRPs, the atom transfer radical polymerization (ATRP) is very popular and adaptable method for the synthesis of polymers with specifically controlled architecture. Two different architectures of NAI and MMA copolymers are reported using ATRP process. The effect of various pedant groups on the rate constants of propagation (k p) and thermal properties NAI and MMA copolymers is studied. The poly(NAI-ran-MMA)-b-poly(MMA) are stable up to 200 °C and degraded in three steps. Whereas, the poly(NAI-ran-MMA)-b-poly(NAI) are stable up to 330 °C and degraded in two steps. The density functional theory methods are used for calculation of equilibrium constants (K ATRP) for the ATRP process for the series of laboratory synthesized alkyl halides. A good agreement was observed between the experimentally determined and theoretically calculated K ATRP values. The mechanistic studies are carried for poly(NAI-ran-MMA) copolymer system using statistical model discrimination method along with 1H decoupled 13C NMR spectroscopy. For studying the mechanism of copolymerization of NAI and MMA via ATRP methods, “trimer model or penultimate model” will be more accurate than “dimer model or terminal model”.

Thermal Conductivity and Phase-Change Properties of Boron Nitride-Lead Oxide Nanoparticle-Doped Polymer Nanocomposites.

Thermally conductive phase-change materials (PCMs) were produced using the crosslinked Poly (Styrene-block-Ethylene Glycol Di Methyl Methacrylate) (PS-PEG DM) copolymer by employing boron nitride (BN)/lead oxide (PbO) nanoparticles. Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) methods were used to research the phase transition temperatures, the phase-change enthalpies (melting enthalpy (ΔHm), and crystallization enthalpies (ΔHc)). The thermal conductivities (λ) of the PS-PEG/BN/PbO PCM nanocomposites were investigated. The λ value of PS-PEG/BN/PbO PCM nanocomposite containing BN 13 wt%, PbO 60.90 wt%, and PS-PEG 26.10 wt% was determined to be 18.874 W/(mK). The crystallization fraction (Fc) values of PS-PEG (1000), PS-PEG (1500), and PS-PEG (10,000) copolymers were 0.032, 0.034, and 0.063, respectively. XRD results of the PCM nanocomposites showed that the sharp diffraction peaks at 17.00 and 25.28 °C of the PS-PEG copolymer belonged to the PEG part. Since the PS-PEG/PbO and the PS-PEG/PbO/BN nanocomposites show remarkable thermal conductivity performance, they can be used as conductive polymer nanocomposites for effective heat dissipation in heat exchangers, power electronics, electric motors, generators, communication, and lighting equipment. At the same time, according to our results, PCM nanocomposites can be considered as heat storage materials in energy storage systems.

Influence of talc and hydrogenated castor oil on the dissolution behavior of metformin-loaded pellets with acrylic-based sustained release coating

Multi-unit pellet system (MUPS) is of great interest as it is amenable to customization. MUPS comprises multi-particulates, usually as pellets or spheroids, which can be coated with diffusion barrier coatings. One commonly used diffusion barrier coating is the methacrylic acid copolymer, which can be used as a taste masking, enteric or sustained release polymer. While the versatility of methacrylic acid copolymers makes them pliable for pellet coating, there are impediments associated with their use. Additives commonly required with this polymer, including plasticizer and anti-adherent, have been shown to weaken the film strength. The objective of this study was to investigate the impact of osmotic pressure within the core on the sustained release coat integrity and functionality. Hydrogenated castor oil (HCO) was chosen as the additive to be studied. Metformin-loaded pellets, prepared via extrusion-spheronization, were coated with ethyl acrylate and methyl methacrylate copolymer (Eudragit RS 30 D) containing talc, talc-HCO, or HCO to different coat thicknesses. Drug release was investigated using the USP dissolution apparatus 2 and an ultraviolet imager. The swelling of the pellets when wetted was monitored by video imaging through a microscope. When coated to 7.5 % coat weight gain, coats with HCO slowed down drug release more than the other pellets. The pellets also swelled the most, which suggests that they were more resistant to the osmotic pressure exerted by metformin. For drugs which exert high osmotic pressure, HCO can serve as an efficient alternative to talc in the preparation of methacrylic acid copolymer coatings.

Fast-release kinetics of a pH-responsive polymer detected by dynamic contact angles.

Polymers conjugated with active agents have applications in biomedicine, anticorrosion, and smart agriculture. When the active agent is used as a drug, corrosion inhibitor, or pesticide, it can be released upon a specific stimulus. The efficiency and the sustainability of active agents are determined by the released kinetics. In this work, we study the fast-release kinetics of 8-hydroxyquinoline (8HQ) from a pH-responsive, random copolymer of methyl methacrylate and 8-quinolinyl-sulfide-ethyl acrylate [P(MMA-co-HQSEA)] by hydrolysis of the β-thiopropionate groups. We used contact angle measurements of sliding drops as an elegant way to characterize the release kinetics. Based on the results gained from 1H nuclear magnetic resonance measurement, fluorescent intensity measurement, and velocity-dependent contact angle measurement, we found that both the hydrolysis rate and polymer conformation affect the release kinetics of 8HQ from a P(MMA-co-HQSEA) film. Polymer chains collapse and further suppress the release from the inner layer in acidic conditions, while polymer chains in a stretched condition further facilitate the release from the inner layer. As a result, the cumulative release rate of 8HQ is higher in the basic condition than in the acidic condition.

Preparation of bamboo-derived structured cellulose and its evaluation as resin composite materials

Bamboo, a highly productive and renewable resource, shows a high strength among other biomass resources. Composites of lignocellulose with a polymer are attracting attention as a new material for buildings and furniture according to recent demands for sustainable development goals (SDGs). The present report describes the first preparation of a composite with resin using an organosolv technique with water and 1-butanol solvent as pre-treatment of bamboo.Organosolv treatment at 453 K selectively removed lignin and hemicellulose from bamboo without causing over-decomposition of cellulose. The delignified bamboo was impregnated with a copolymer of methyl methacrylate and hydroxyethyl methacrylate using a decompressed method. The structure of the bamboo-derived cellulose piece remained the same as it was after polymer impregnation without any molding process. Amount of the polymer impregnated into the bamboo after organosolv was significantly greater (34%) than that without organosolv.Impregnated state in the delignified bamboo was evaluated using morphological observations and determination of the properties of mesopores, which formed in the gap between cellulose microfibrils during organosolv. Results indicated that the composite of bamboo-derived structured cellulose with the co-polymer was prepared successfully, and the vascular bundles, including cell walls as well as parenchyma cells, were impregnated with the resin. Compressive strength of impregnated delignified bamboo was evaluated and found to be 12.7 MPa.