Poly Methyl Methacrylate Phase Research Articles

4D Printing of Magneto‐Thermo‐Responsive PLA/PMMA/Fe3O4 Nanocomposites with Superior Shape Memory and Remote Actuation

AbstractThis study presents the development and 4D printing of magnetic shape memory polymers (MSMPs) utilizing a composite of polylactic acid (PLA), polymethyl methacrylate (PMMA), and Fe3O4 nanoparticles. The dynamic mechanical analysis reveals that the integration of Fe3O4 maintains the broad thermal transition without significantly affecting α‐relaxation time, indicating high compatibility and homogeneous distribution of the nanoparticles within the polymer matrix. Field emission scanning electron microscopy further confirms the high compatibility of PLA and PMMA phases as well as uniform dispersion of Fe3O4 nanoparticles, essential for the effective transfer of heat during the shape memory process. Significantly, the incorporation of magnetic nanoparticles enables remote actuation capabilities, presenting a substantial advancement for biomedical applications. 4D‐printed MSMP nanocomposites exhibit exceptional mechanical properties and rapid, efficient shape memory responses under both inductive and direct heating stimuli, achieving 100% shape fixity and 100% recovery within ≈85 s. They are proposed as promising candidates for biomedical implants, specifically for minimally invasive implantation of bone scaffolds, due to their rapid remote actuation, biocompatibility, and mechanical robustness. This research not only demonstrates the 4D printability of high‐performance MSMPs but also introduces new possibilities for the application of MSMPs in regenerative medicine.

Strength Evaluation of Functionalized MWCNT-Reinforced Polymer Nanocomposites Synthesized Using a 3D Mixing Approach.

The incorporation of carboxyl functionalized multi-walled carbon nanotube (MWCNT- COOH) into a polymethyl methacrylate (PMMA) has been investigated. The resultant tensile and flexural mechanical properties have been determined. In this paper, a novel synthesis process for a MWCNT-reinforced polymer nanocomposite is proposed. The proposed method significantly eliminates the most challenging issues of the nano-dispersed phase, including agglomeration and non-homogeneous mixing within a given matrix material, and also resolves the issues occurring in conventional mixing processes. The results of scanning electron microscopy support these claims. This 3D-mixing process is followed by an extrusion process, using a twin-screw extruder for pristine MWCNT, and a compression molding process for COOH-MWCNT, to prepare test specimens for experimentally determining the mechanical properties. The test specimens are fabricated using 0.1, 0.5, and 1.0 wt.% MWCNT, with a remaining PMMA phase. The testing is conducted according to ASTM D3039 and ASTM D7264 standards. Significant improvements of 25.41%, 35.85%, and 31.75% in tensile properties and 18.27%, 48%, and 33.33% in flexural properties for 0.1, 0.5, and 1.0 wt.% COOH-MWCNT in PMMA, respectively, compared to non-functionalized MWCNTs, were demonstrated. The highest strength was recorded for the nanocomposite with 0.5 wt.% f-MWCNT content, indicating the best doping effect at a lower concentration of f-MWCNT. The proposed CNT-PMMA nanocomposite may be found suitable for use as a scaffold material in the domain of bone tissue engineering research. This type of research possesses a high strength requirement, which may be fulfilled using MWCNT. Furthermore, this analysis also shows a significant amount of enhancement in flexural strength, which is clinically required for fabricating denture bases.

Green-High-Performance PMMA–Silica–Li Barrier Coatings

Organic-inorganic coatings based on polymethyl methacrylate (PMMA)–silica–lithium are an efficient alternative to protect metals against corrosion. Although the preparation methodology is established and the thin coatings (~10 µm) are highly protective, the use of an environmentally friendly solvent has not yet been addressed. In this work, PMMA–silica coatings were synthesized using 2-propanol as a solvent and deposited on aluminum alloy AA7075, widely used in the aeronautical industry. Different concentrations of lithium carbonate (0–4000 ppm) were incorporated into the hybrid matrix to study the structural and inhibitive effects of Li+ in terms of barrier efficiency of the coatings in contact with saline solution (3.5% NaCl). Structural and morphological characterization by low-angle X-ray scattering, X-ray photoelectron spectroscopy, atomic force microscopy, thermogravimetric analysis, thickness, and adhesion measurements, showed for intermediate lithium content (500–2000 ppm) the formation of a highly polymerized PMMA phase covalently cross-linked by silica nodes, which provide strong adhesion to the aluminum substrate (15 MPa). Electrochemical impedance spectroscopy (EIS) results revealed an excellent barrier property in the GΩ cm2 range and durability of more than two years in a 3.5% NaCl solution. This performance can be attributed to the formation of a highly reticulated phase in the presence of Li, which hinders the permeation of water and ions. Additionally, the self-healing ability of scratched samples was evidenced by EIS assays showing a fast Li-induced formation of insoluble products in damaged areas; thus, constituting an excellent eco-friendly solution for corrosion protection of aerospace components.

Transparent PC/PMMA Blends with Enhanced Mechanical Properties via Reactive Compounding of Functionalized Polymers.

Reactive compounding of terminally phenolic OH-functionalized polycarbonate (PC) with epoxy-functionalized polymethylmethacrylate (PMMA) prepared by copolymerization with glycidyl methacrylate was investigated. It was spectroscopically demonstrated that a PC/PMMA copolymer was formed during the melt reaction of the functional groups. Zirconium acetylacetonate could catalytically accelerate this reaction. Correlations of the phenomenological (optical and mechanical) properties with the molecular level and mesoscopic (morphological) structure were discussed. By the investigated reactive compounding process, transparent PC/PMMA blends with two-phase morphologies were obtained in a continuous twin-screw extruder, which, for the first time, combined the high transmission of visible light with excellent mechanical performance (e.g., synergistically improved tensile and flexural strength and high scratch resistance). The transparency strongly depended on (a) the degree of functionalization in both PC and PMMA, (b) the presence of the catalyst, and (c) the residence time of the compounding process. The in-situ-formed PC/PMMA copolymer influenced the observed macroscopic properties by (a) a decrease in the interphase tension, leading to improved and stabilized phase dispersion, (b) the formation of a continuous gradient of the polymer composition and thus of the optical refractive indices in a diffuse mesoscopic interphase layer separating the PC and PMMA phases, and (c) an increase in the phase adhesion between PC and PMMA due to mechanical polymer chain entanglement in this interphase.

Dynamic mechanical behaviors of nacre-inspired graphene-polymer nanocomposites depending on internal nanostructures

Nacre, a natural nanocomposite with a brick-and-mortar structure existing in the inner layer of mollusk shells, has been shown to optimize strength and toughness along the laminae (in-plane) direction. However, such natural materials more often experience impact load in the direction perpendicular to the layers (i.e., out-of-plane direction) from predators. The dynamic responses and deformation mechanisms of layered structures under impact load in the out-of-plane direction have been much less analyzed. This study investigates the dynamic mechanical behaviors of nacre-inspired layered nanocomposite films using a model system that comprises alternating multi-layer graphene (MLG) and polymethyl methacrylate (PMMA) phases. With a validated coarse-grained molecular dynamics simulation approach, we systematically study the mechanical properties and impact resistance of the MLG-PMMA nanocomposite films with different internal nanostructures, which are characterized by the layer thickness and number of repetitions while keeping the total volume constant. We find that as the layer thickness decreases, the effective modulus of the polymer phase confined by the adjacent MLG phases increases. Using ballistic impact simulations to explore the dynamic responses of nanocomposite films in the out-of-plane direction, we find that the impact resistance and dynamic failure mechanisms of the films depend on the internal nanostructures. Specifically, when each layer is relatively thick, the nanocomposite is more prone to spalling-like failure induced by compressive stress waves from the projectile impact. Whereas, when there are more repetitions, and each layer becomes relatively thin, a high-velocity projectile sequentially penetrates the nanocomposite film. In the low projectile velocity regime, the film develops crazing-like deformation zones in PMMA phases. We also show that the position of the soft PMMA phase relative to the stiff graphene sheets plays an important role in the ballistic impact performance of the investigated films. Our study provides insights into the effect of nanostructures on the dynamic mechanical behaviors of layered nanocomposites, which can lead to effective design strategies for impact-resistant films.

A novel fabrication procedure for producing high strength hydroxyapatite ceramic scaffolds with high porosity

Hydroxyapatite (HA) scaffolds were fabricated using the space holder method with a pressureless sintering process in a systematically developed manner at different fabrication stages to increase the strength of the scaffold at high porosity. Polyvinyl alcohol (PVA) and Polymethyl methacrylate (PMMA) were used as binders and space holder agents, respectively. The physical properties of the HA scaffolds were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), linear shrinkage test, and porosity measurements. The mechanical properties of the HA scaffolds were analyzed using compressive strength measurements. The results revealed that the HA scaffold met the expected quality requirements with a compressive strength of 2.2 MPa at a porosity of 65.6% with pore sizes distributed in the range of 126–385 μm. The shrinkage of the scaffold diameter occurred by 20.27%, this diameter shrinkage predominantly to the shrinkage of the HA scaffold caused by sintering. Besides, suspect that a higher PMMA concentration causes pore size shrinkage upon sintering. The formation of pore interconnections was evidenced by SEM observations and the ‘translucent light method’ developed in this study. The results of the scaffold phase test using XRD showed that the final scaffold consisted only of the HA phase, as the PVA and PMMA phases burned out during the sintering process.

Microcellular PLA/PMMA foam fabricated by CO2 foaming with outstanding shape-memory performance

Porous shape memory polymers (SMPs) are attracting people's attention due to their extensive application prospect. Herein, a novel and flexible method to produce bio-friendly polylactic acid (PLA)/polymethyl methacrylate (PMMA) shape memory foam by a two-step CO2 microcellular foaming is proposed. The achieved foams exhibit outstanding shape memory performance, such as a maximum shape fixity ratio of 98 %, a maximum shape recovery ratio of 86 %, and further the recovery ratio remaining more than 75 % even after 10 compression-recovery cycles. The additive PMMA phases uniformly disperse with spherical morphology in nanoscale, and they result in the greatly decreased crystallinity and crystal size of PLA. Meanwhile, the extensive interfaces lead to increased crystal density. In this context, more amorphous molecular chains left in the cell wall act as reversible segments, and more numerous denser crystals act as net points, which together can decrease the resistance in the shape memory process, thus, facilitating the significant promotion of shape memory capability of the as-achieved PLA/PMMA foams. Therefore, it exhibits a promising future to produce environmentally friendly SMPs by a simple, cost-efficient, and clean microcellular foaming technology.

Preparation of Cylindrical Janus Particles Using a Stirring Method.

We previously discovered a novel method for the preparation of polymer particles that have a cylindrical shape. Polystyrene (PS) or poly methyl methacrylate (PMMA) spherical particles were deformed into a cylindrical shape by stirring with a magnetic stirrer in a polyvinylpyrrolidone (PVP) aqueous solution. In this study, cylindrical “Janus” particles consisting of PS and PMMA were prepared by this stirring method. In the case of spherical Janus particles, cylindrical particles were obtained after stirring; however, the direction of the interface between the PS and PMMA phases was random. However, in the case of snowman-like Janus particles, cylindrical Janus particles with the interface at the center of the long axis were successfully prepared. This indicated that the extension direction can be controlled owing to the anisotropic shape and supported the proposed deformation mechanism of the cylindrical particles. Moreover, amphiphilic cylindrical Janus particles were also successfully prepared by hydrolysis of only one phase to introduce carboxy groups.

Heat transport across phase interface in silica aerogel/polymethyl methacrylate composites

Heat transport can be dictated by the phase interface in micro- and nanostructured systems. In this research, silica aerogel (SA)/polymethyl methacrylate (PMMA) hybrid composites were prepared to investigate a link between interfacial interaction and heat transport. Using scanning electron microscopy, nitrogen adsorption-desorption tester, Fourier transform infrared spectrometer, thermogravimetric analysis, we characterized effects of phase interface on the performance of SA/PMMA hybrid composites. A time-domain thermoreflectance technique was employed for the investigation of changes of heat transport across the phase interface. The results indicated that varying interfacial interaction within SA phase and PMMA phase modulates all microstructure, mechanical properties and thermal properties. The stronger interface bond strength of covalent bonds facilitated the coupling effect for phonon transmission, which led to more efficient heat transport than non-covalent bonds. The stronger interface bond strength also improved the mechanical properties of composites. Coupling effect of Si-O bonds for phonon transmission is better than that of C-C bonds. The long molecular chain of polydivinylsiloxane (AP) improved the flexibility of SA-AP/PMMA hybrid composites.

Investigating phase separation and structural coloration of self-assembled ternary polymer thin films

Poly(3-hexylthiophene-2,5-diyl) (P3HT) can generate nanoporous structures with variable pore diameters ranging from 150 to 600 nm from spin-coated blends with polystyrene (PS). In the present study, we observe the effect of the addition of polymethylmethacrylate (PMMA) to P3HT:PS blends to increase the pore-to-pore dimensions up to the micrometer scale. The phase separation in the ternary blend can be directly visualized by replacing the commercial (non-emissive) PS with a boron-dipyrromethene functionalized PS to distinctively locate the red-emitting P3HT and the green-emitting PS phases. In particular, in the ternary blend with high PMMA contents, we observe that PS acts as a compatibilizing agent at the interface between the P3HT and PMMA phases. After selective removal of the PS and PMMA phases using acetone, we demonstrate that, in these P3HT structured thin films, iridescence can be observed as they exhibit angle dependent reflectivity which is further emphasized when covered with a thin metal layer. The metal covered nanostructured P3HT films display bright color switching properties with blue and red emission at low and high reflection angles, respectively.

Solid-state poly(ethylene glycol)-polyurethane/polymethylmethacrylate/rutile TiO 2 nanofiber composite electrolyte-correlation between morphology and conducting properties

A series of lithium electrolyte materials based on hybrid of semi Inter penetrating Polymer Network of [poly(ethylene glycol)-polyurethane-polymethylmethacrylate] [60:40] and TiO 2 nanofibers is described. TiO 2 nanofibers are made by simple solvothermal procedure. Rutile phase of TiO 2 and its fibrous morphology are confirmed by X-ray diffraction pattern and scanning electron microscopy image respectively. Semi Inter penetrating Polymer Network of polyethylene glycol-polyurethane/polymethylmethacrylate with LiClO 4 and its nanocomposite with different weight percent of TiO 2 nano fibers have been synthesized. The formation of Inter penetrating Polymer Network and its amorphous nature are confirmed by Fourier transform infrared spectra, X-ray diffraction pattern and differential scanning calorimetry results. Thermo gravimetric analysis shows enhanced thermal stability of the composite compared to the semi Inter penetrating Polymer Network system. The electrical characterizations of the nanocomposites are done by current–voltage ( I– V) measurements and impedance spectroscopy. These results confirm that incorporation of TiO 2 nanofibers by 18% enhances the conductivity of the Inter penetrating Polymer Network system by ten times . The nanoscale structure of the inorganic material is found to be responsible for the bulk properties of the system, especially those that differ from the properties of similar, pure salt-in-polymer electrolytes. Further differential scanning calorimetry, scanning electron microscopy and impedance data confirm the presence of two polymeric phases in the semi Inter penetrating Polymer Network. Power law exponents of individual phase of that semi Inter penetrating Polymer Network obtained by simulated fitting of the conductivity versus log frequency profile using universal power law reveals that cationic hopping in the polymethylmethacrylate phase and anionic hopping in the polyethylene glycol-polyurethane phase contribute significantly to the charge transport processes in these semi Inter penetrating Polymer Network.

PMMA Highlights the Layering Transition of PDMS in Langmuir Films

We report a system consisting of a mixed Langmuir monolayer, made of water-insoluble, spreadable, fluid-like polymers polydimethylsiloxane (PDMS) and polymethylmethacrylate (PMMA) with a minority P(DMS-b-MMA) copolymer. We have performed both Langmuir trough pressure/area isotherm measurements and Brewster angle microscopy (BAM) observations and complement the experiments with molecularly detailed self-consistent field (SCF) calculations. PDMS undergoes a layering transition that is difficult to detect by BAM. Addition of PMMA gives contrast in BAM, now showing a two-phase system: if this would consist of separate two-dimensional (2D) PMMA and PDMS phases, a PDMS-PMMA diblock should accumulate at the phase boundary. However, the diblock copolymer of PDMS-PMMA failed to show the expected "lineactant" behavior, i.e., failed to accumulate at the phase boundary. The calculations point to a nontrivial arrangement of the polymer chains at the interface: in mixtures of the two homopolymers, in a rather wide composition ratio, we find a vertical (with respect to the air/water interfacial plane) configuration, with PMMA sitting preferably at the PDMS/water interface of the thicker PDMS film, during the PDMS layering phase transition. This also explains why the diblock copolymer is not a lineactant. Both PMMA and P(DMS-b-MMA) are depleted from the thin-thick PDMS film interface, and the line tension between the phases is, consequently, increased, in the binary mixtures as well as in the ternary ones.

Block balance in hydrogenated polybutadiene‐b‐polymethylmethacrylate diblock copolymer for efficient interfacial activity in low‐density polyethylene/polymethylmethacrylate blend: Phase morphology development

AbstractThe objective of the present study was to determine the best molecular balance between the two hydrogenated polybutadiene (HPB) and polymethylmethacrylate (PMMA) blocks that promotes an HPB‐b‐PMMA diblock copolymer with efficient compatibilization activity in a low‐density polyethylene (LDPE)/PMMA immiscible blend. The model blend selected, LDPE/PMMA, is “more immiscible” than the LDPE/polystyrene pair largely reported in open literature. The blends having a composition of 80LDPE/20PMMA exhibit a droplet‐in‐matrix phase morphology whereas in 20LDPE/80PMMA a co‐continuous phase morphology was developed. In the droplet‐in‐matrix phase morphology, the emulsifying efficiency of the copolymer was evaluated based on the maximum reduction of the PMMA droplet size it is able to promote. Whereas, in the co‐continuous phase morphology, the copolymer was evaluated based on its ability to stabilize the maximum phase co‐continuity. The sequences of the best emulsifying copolymer revealed are not symmetrical. An HPB‐b‐PMMA where the ratio of molar mass of the blocks, $\overline{M_{\rm n}}$ HPB/$\overline{M_{\rm n}}$ PMMA, is within 1.8–1.95 exhibits a much better interfacial activity in LDPE/PMMA blends than a copolymer of much lower ratio (longer PMMA block). This is ascribed to the much higher interactions (cohesive energy density) encountered in PMMA (PMMA of the copolymer and PMMA phase of the blend) compared with the LDPE side (HPB of the copolymer and LDPE phase of the blend). © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 837–848, 2005

Synthesis of macroporous hydroxyapatite scaffolds for bone tissue engineering.

A novel method of preparing macroporous hydroxyapatite (HA) by dual-phase mixing was developed: HA slurry and Polymethylmethacrylate (PMMA) resin were mixed together at the volume ratio of 1:1. After pyrolytic removal of the PMMA phase, HA with an open porous structure was obtained. In this way, the porosity of the ceramic was limited to 50%. Attempts to increase the porosity by adding more PMMA resin were confronted with the technical hurdle of sample collapse during the pyrolysis process. To increase the porosity and to improve pore interconnection, an extra foaming step was introduced before the polymerization of PMMA resin. Three foaming agent systems were tried, based on the reactions of citric acid and (bi)carbonate salts: sodium bicarbonate, calcium carbonate, and ammonium bicarbonate. Although all the three foaming agents were able to increase the porosity up to 70%, keeping all the pores interconnected throughout, only ammonium bicarbonate system turned out to be applicable to make HA scaffolds or implants, because both NaHCO(3) and CaCO(3) systems caused alkalic residues in the final ceramic. The porous HA samples were fully characterized by FTIR, XRD, ESEM (EDX), and optical microscopy.

Zinc oxide/polymethylmethacrylate composite microspheres by in situ suspension polymerization and their morphological study

Homogenously zinc oxide (ZnO)-dispersed polymethylmethacrylate (PMMA) composite microspheres were produced considering the interfacial characteristics of ZnO and PMMA in in situ suspension polymerization. The morphological observation with electron microscopes revealed that nano-sized ZnO particles were embedded homogeneously in the inner part of PMMA microspheres. Moreover, their spherical shape could be maintained to a large amount of ZnO in the PMMA phase. From this study, it was found that one of key requirements in the synthesis of inorganic/polymer composite microspheres was the enhanced interfacial compatibility between inorganic and polymer, which was achieved by treating the surface of inorganics hydrophobically and imparting conformational anchorage factor at inorganic interfaces.

Small‐angle x‐ray analysis of latex particles using contrast variation

AbstractA study of a core‐shell latex consisting of a polystyrene core and a polymethylmethacrylate (PMMA) shell by small‐angle x‐ray scattering is presented. Since the electron density, i.e., the contrast of both polymers, can be easily matched by addition of sucrose to the dispersing agent water, the internal structure of the particles can be studied by contrast variation. The scattering intensities obtained at different contrast are all compatible with a concentric core‐shell model which exhibits a finite nonuniformity of the thickness of the shell. The present analysis furthermore reveals that the interfacial region between the polystyrene and the PMMA phase must be very small.