PMMA Content Research Articles

A strategy for achieving high-performance single layer polymer photodetectors through dark current reduction using PMMA additives

Suppressing dark current density is crucial for optimizing the performance of organic photodetectors (PDs), particularly in terms of detectivity (D∗) and linear dynamic range (LDR). Organic PDs often utilize the bulk heterojunction structure of organic solar cells to significantly increase photocurrent. However, unlike solar cells, which are unaffected by dark current, photodetectors' performance is substantially limited by it. The interconnected network of bulk heterojunctions leads to a noticeable increase in dark current, thus degrading device performance. Typically, reducing dark current involves adding a modification layer or using multilayer planar heterojunctions, which effectively reduce dark current but often delay response speed and complicate manufacturing. This study presents an alternative approach by incorporating a small concentration of PMMA into single-layer polymer photodetectors, significantly reducing dark current without affecting photocurrent. For this single-layer polymer PD, an ultra-low dark current density of 1.25 × 10−8 A/cm2, a high Dsh∗ of 2.74 × 1012 Jones, an LDR of 120.5 dB, and a fast response time with 1.6 μs were achieved. The capacitance-voltage (C-V), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and atomic force microscopy (AFM) measurements revealed that the PMMA additive reduces internal defects, increases bulk resistance, optimizes phase separation, and enhances carrier transport efficiency. The improved device performances are attributed to a more efficient vertical arrangement of the donor-acceptor interface and carrier channels, thus reducing carrier recombination loss. These findings offer a new direction for fabricating high-performance single-layer photodetectors.

Optimizing pH sensor performance with PANI/PMMA composite thin films: Impedimetric and capacitive transduction approaches

The continuous search for novel materials to meet the requirements of modern technological applications has led to the widespread use of polyaniline (PANI) composites for sensing purposes. Although research has been carried out on both chemical sensors using PANI/polymer composites and chemical sensors with impedimetric/capacitive transduction using PANI composites, there is still a gap in the use of PANI/polymer composites in impedimetric and capacitive transduction platforms for pH sensing. In this study, the influence of composite thin films consisting of PANI and poly(methyl methacrylate) (PMMA) on the sensitivity and linearity of pH sensors based on electrochemical impedance and capacitance spectroscopy (EIS/ECS) was evaluated. The sensitivity and linearity of the devices showed a dependence on the polymer content. For PANI:PMMA equal to 30:70, the EIS and ECS sensitivity reached 12.6 ± 2.7 and 18.7 ± 4.9 %/pH, respectively, after reaching its minimum value for the 50:50 sample. Similarly, the linearity values for the 30:70 sample were 92.7 % and 99.8 % for EIS and ECS, respectively. We were able to encapsulate the PANI in the PMMA matrix, which improved the control of ion diffusion and analyte access to the active redox quinoid rings on the PANI. As a result, the saturation effect of the polymer was reduced. By adjusting the relative content of PANI and PMMA, the structure and properties of the composite can be controlled, directly affecting the sensor parameters. These materials have potential applications in sensors for various fields such as food, biomedical and environmental monitoring, with the ability to tailor their properties for optimal response.

Mechanical and electric friction properties of Poly(methyl methacrylate) – Nitrocellulose blend polymer for triboelectric nanogenerators

In this study, nitrocellulose - polymethyl methacrylate (NC/PMMA) blend film as a positive triboelectric material for triboelectric nanogenerator (TENG) with controlled flexibility was successfully synthesized by varying the PMMA content in the polymer blend. The combination of NC and PMMA reduced the limitations of the individual component materials with improved mechanical properties such as tensile strength, elastic modulus and elongation at breaking point. The TENG fabricated from NC/PMMA as a positive friction layer paired with fluorinated ethylene propylene (FEP) or polytetrafluoroethylene (PTFE) as a negative friction layer demonstrates a high peak to peak voltage output of 234 V at low frequency and with an actuation force of 10~N. The open circuit triboelectric voltage value maintains 91% durability after 26200 click-release cycles. This work provides a potential approach to simultaneously improve the electrical and mechanical properties of triboelectric materials, promoting the possibility of practical applications of TENG.

Preparation and Characterization of Poly(Methyl Methacrylate) Grafted Natural Rubber Latex Films

Poly(methyl methacrylate) (PMMA) grafted natural rubber (NR) latex was successfully prepared and solely exploited even at high MMA concentration (1.5 mol/kg-rubber) to make coherent and uniform vulcanized films without blending with other polymer to achieve excellent physical properties. High ammonia natural rubber (HANR) latex was subjected to graft-copolymerization with methyl methacrylate (MMA) monomer in the presence of tert-butyl hydroperoxide (TBHP) and tetraethylenepentamine (TEPA). High conversion, i.e., 85.12 mol%, and grafting efficiency, i.e., 92.70 mol%, were obtained at 1.5 mol/kg-rubber MMA. The resulting gross PMMA grafted NR (1.5PMMA) latex was then compounded, dipped, and vulcanized to produce thin films. The tensile strength and modulus at 300 percent (M300) of vulcanized 1.5PMMA film were superior to vulcanized HANR film by 1-fold. While elongation at break (EB) was identical to each other due to the high gel content in both vulcanized films. Besides, the vulcanized 1.5PMMA film absorbed less oil compared to HANR film. The thermal stability of vulcanized 1.5PMMA film was found to be higher than that of vulcanized HANR film. Hence, it can be deduced that controlling the graft-copolymerization of PMMA in NR latex is the key to produce coherent thin films with improved properties at higher PMMA content.

Oral vitamin B12 supplementation in pernicious anemia: a prospective cohort study

BackgroundThe absorption of vitamin B12 is hindered in pernicious anemia (PA) owing to intrinsic factor deficiency. Traditionally, intramuscular vitamin B12 injections were the standard treatment, bypassing the impaired absorption. Although there is potential for oral vitamin B12 supplementation through passive enteral absorption, it is not commonly prescribed in PA owing to limited studies assessing its efficacy. ObjectivesWe aimed to assess the efficacy of oral vitamin B12 supplementation in PA. MethodsWe enrolled participants diagnosed with incident vitamin B12 deficiency related to PA. The diagnosis of PA was based on the presence of classical immune gastritis and of anti-intrinsic factor and/or antiparietal cell antibodies. To evaluate the vitamin B12 status, we measured total plasma vitamin B12, plasma homocysteine, and plasma methylmalonic acid (pMMA) concentration and urinary methylmalonic acid–to–creatinine ratio. Participants were treated with oral cyanocobalamin at a dosage of 1000 μg/d throughout the study duration. Clinical and biological vitamin B12 deficiency related features were prospectively and systematically assessed over the 1-y study duration. ResultsWe included 26 patients with vitamin B12 deficiency revealing PA. Following 1 mo of oral vitamin B12 supplementation, 88.5% of patients were no longer deficient in vitamin B12, with significant improvement of plasma vitamin B12 [407 (297–485) compared with 148 (116–213) pmol/L; P < 0.0001], plasma homocysteine [13.5 (10.9–29.8) compared with 18.6 (13.7–46.8) μmol/L; P < 0.0001], and pMMA [0.24 (0.16–0.38) compared with 0.56 (0.28–1.09) pmol/L; P < 0.0001] concentrations than those at baseline. The enhancement of these biological parameters persisted throughout the 12-month follow-up, with no patients showing vitamin B12 deficiency by the end of the follow-up period. The median time to reverse initial vitamin B12 deficiency abnormalities ranged from 1 mo for hemolysis to 4 mo for mucosal symptoms. ConclusionsOral supplementation with 1000 μg/d of cyanocobalamin has been shown to improve vitamin B12 deficiency in PA.

Influence of FRET, charge separation, and density of defect states on the improvement of UV light-driven photocatalytic activity of PMMA capped ZnO nanomaterials

This study employs oxidative polymerization, co-precipitation, and ex-situ surface capping techniques to fabricate pristine PMMA, ZnO, and PMMA-capped ZnO specimens with varying PMMA concentrations. X-ray diffraction reveals reduced directional growth of ZnO, while Fourier transform infrared spectroscopy confirms PMMA chain bonding with ZnO in PMMA-capped specimens. Scanning electron microscopy illustrates decreased average length and thickness of ZnO nanoplates post-surface modification, indicating a robust interaction between PMMA and ZnO. X-ray photoelectron spectroscopy identifies suppressed defects, including zinc interstitials and oxygen vacancies, affirming ZnO surface capping by PMMA. Absorption spectra display a blue shift in band-edge or increased bandgap, attributed to the combined effects of band alignment offset and reduced oxygen vacancy states. Luminescence spectra show gradual quenching linked to PMMA content increase, with defect-related emission suppression attributed to ZnO surface capping. UV emission suppression is ascribed to donor concentration-dependent Förster resonance energy transfer (FRET) from PMMA to ZnO. Photocatalytic tests reveal enhanced efficiency in PMMA-capped ZnO catalysts attributed to synergies involving charge separation, bulk recombination centers, oxygen vacancy states, and FRET. Efficiency improves with higher PMMA content, aligning with changes in emission intensity. The study demonstrates emission intensities' tunability through surface capping and donor concentration-dependent FRET, ultimately influencing degradation efficiency.

Facile encapsulation of cyanoacrylate-based bioadhesive by electrospray method and investigation of the process parameters

Polymer microcapsules containing cyanoacrylates have represented a promising option to develop self-healing biomaterials. This study aims to develop an electrospray method for the preparation of capsules using poly(methyl methacrylate) (PMMA) as the encapsulant and ethyl 2-cyanoacrylate (EC) as the encapsulate. It also aims to study the effect of the electrospray process parameters on the size and morphology of the capsules. The capsules were characterized using Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and field-emission scanning electron microscopy (FE-SEM). Moreover, the effects of electrospray process parameters on the size were investigated by Taguchi experimental design. FTIR and TGA approved the presence of both PMMA and EC without further reaction. FE-SEM micrograph demonstrated that an appropriate choice of solvents, utilizing an appropriate PMMA:EC ratio and sufficient PMMA concentration are critical factors to produce capsules dominantly with an intact and spherical morphology. Utilizing various flow rates (0.3–0.5 ml/h) and applied voltage (18–26 kV), capsules were obtained with a 600–1000 nm size range. At constantly applied voltages, the increase in flow rate increased the capsule size up to 40% (ANOVA, p ≤ 0.05), while at constant flow rates, the increase in applied voltage reduced the average capsule size by 3.4–26% (ANOVA, p ≤ 0.05). The results from the Taguchi design represented the significance of solution flow rate, applied voltage, and solution concentration. It was shown that the most effective parameter on the size of capsules is flow rate. This research demonstrated that electrospray can be utilized as a convenient method for the preparation of sub-micron PMMA capsules containing EC. Furthermore, the morphology of the capsules is dominated by solvents, PMMA concentration, and PMMA:EC ratio, while the average size of the capsules can be altered by adjusting the flow rate and applied voltage of the electrospray process.

Development of poly(methyl methacrylate)/poly(lactic acid) blend as sustainable biomaterial for dental applications

Poly(lactic acid) (PLA) is gaining popularity in manufacturing due to environmental concerns. When comparing to poly(methyl methacrylate) (PMMA), PLA exhibits low melting and glass transition temperature (Tg). To enhance the properties of these polymers, a PMMA/PLA blend has been introduced. This study aimed to investigate the optimal ratio of PMMA/PLA blends for potential dental applications based on their mechanical properties, physical properties, and biocompatibility. The PMMA/PLA blends were manufactured by melting and mixing using twin screw extruder and prepared into thermoplastic polymer beads. The specimens of neat PMMA (M100), three different ratios of PMMA/PLA blends (M75, M50, and M25), and neat PLA (M0) were fabricated with injection molding technique. The neat polymers and polymer blends were investigated in terms of flexural properties, Tg, miscibility, residual monomer, water sorption, water solubility, degradation, and biocompatibility. The data was statistically analyzed. The results indicated that Tg of PMMA/PLA blends was increased with increasing PMMA content. PMMA/PLA blends were miscible in all composition ratios. The flexural properties of polymer blends were superior to those of neat PMMA and neat PLA. The biocompatibility was not different among different composition ratios. Additionally, the other parameters of PMMA/PLA blends were improved as the PMMA ratio decreased. Thus, the optimum ratio of PMMA/PLA blends have the potential to serve as novel sustainable biomaterial for extensive dental applications.

Multilevel crystalline structures and post-stretching induced structural evolutions of poly(vinylidene fluoride)-based cast films

Poly(vinylidene fluoride) (PVDF) films have been widely used as ferro- and piezoelectric materials, battery separators and filtration membranes. Blending with poly(methyl methacrylate) (PMMA) is an effective way to fabricate the PVDF-based films with high physical performances. However, the multilevel structures and structural evolutions of PVDF/PMMA films during processing are not well understood. Herein, we prepared the PVDF and PVDF/PMMA cast films and investigated their multilevel structures and structural evolutions during post-stretching. We find that the PVDF cast films with higher melt-draw ratio (RMD) possess raw-nucleated lamellar morphology, which endows the films with hard-elastic behavior. PVDF cast films exclusively form the α phase during casting. However, blending PVDF with PMMA results in the formation of PVDF β phase, which is favoured at a higher PMMA content (mPMMA) or larger RMD. The stress-accelerated crystallization and the PVDF/PMMA intermolecular interactions are responsible for the formation of PVDF β phase. In the post-stretching process, PVDF cast films undergo cavitation, fragmentation of lamellar skeleton, generation of new lamellae and α-to-β phase transition with the increase of strain. For PVDF/PMMA cast films, the cavitation is sensitive to the content of PVDF α phase and is supressed in the films containing solely β phase.

3D‐printed alumina‐based ceramics with spatially resolved porosity

AbstractThe interest on porous ceramics has increased in the last years with the developments in additive manufacturing methods, enabling design of components with complex geometries for membranes, filters, catalytic converters, or biostructures. In this study, porous alumina samples were produced by using different concentrations of poly(methyl methacrylate) (PMMA) as pore‐forming agent (PFA) in a photocurable slurry via vat photopolymerization (VPP). The effect of layer thickness, PMMA particle size, and sintering temperature on the mechanical properties and microstructural features of the samples was investigated as a function of PMMA concentration. It is shown that the mechanical properties of 3D‐printed porous alumina are comparable with those fabricated by conventional processes. The Young modulus, fracture toughness as well as the biaxial strength decreased with increasing weight concentration of PFA (resulting in an increased total porosity). Specially using smaller PMMA particles has a positive effect, resulting in higher Young's modulus as well as fracture toughness. The feasibility of VPP for fabricating novel parts with more complex porosity regions is explored by printing multi‐material samples and porosity‐graded architectures. The counterbalance effect between porosity and mechanical properties may be optimized by tailoring material composition and processing parameters.

In vitro assessment of inflammatory skin potential of poly(methyl methacrylate) at non-cytotoxic concentrations.

Poly(methyl methacrylate) (PMMA) is considered an attractive substrate material for fabricating wearable skin sensors such as fitness bands and microfluidic devices. Despite its widespread use, inflammatory and allergic responses have been attributed to the use of this material. Therefore, the main objective of this study was to obtain a comprehensive understanding of potential biological effects triggered by PMMA at non-cytotoxic concentrations using in vitro models of NIH3T3 fibroblasts and reconstructed human epidermis (RhE). It was hypothesized that concentrations that do not reduce cell viability are sufficient to activate pathways of inflammatory processes in the skin. The study included cytotoxicity, cell metabolism, cytokine quantification, histopathological, and gene expression analyses. The NIH3T3 cell line was used as a testbed for screening cell toxicity levels associated with the concentration of PMMA with different molecular weights (MWs) (i.e., MW ~5,000 and ~15,000 g/mol). The lower MW of PMMA had a half-maximal inhibitory concentration (IC50 ) value of 5.7 mg/cm2 , indicating greater detrimental effects than the higher MW (IC50 = 14.0 mg/cm2 ). Non-cytotoxic concentrations of 3.0 mg/cm2 for MW ~15,000 g/mol and 0.9 mg/cm2 for MW ~5,000 g/mol) induced negative metabolic changes in NIH3T3 cells. Cell viability was severely reduced to 7% after the exposure to degradation by-products generated after thermal and photodegradation degradation of PMMA. PMMA at non-cytotoxic concentrations still induced overexpression of pro-inflammatory cytokines, chemokines, and growth factors (IL1B, CXCL10, CCL5, IL1R1, IL7, IL17A, VEGFA, FGF2, IFNG, IL15) on the RhE model. The inflammatory response was also supported by histopathological and gene expression analyses of PMMA-treated RhE, indicating tissue damage and gene overexpression. Results suggested that non-cytotoxic concentrations of PMMA (3.0 to 5.6 mg/cm2 for MW ~15,000 g/mol and 0.9 to 2.1 mg/cm2 for MW ~5,000 g/mol) were sufficient to negatively alter NIH3T3 cells metabolism and activate inflammatory events in the RhE skin.

Improved Flexible Triboelectric Nanogenerator Based on Tile‐Nanostructure for Wireless Human Health Monitor

Triboelectric nanogenerators (TENGs) have emerged as promising candidates for integrating with flexible electronics as self‐powered systems owing to their intrinsic flexibility, biocompatibility, and miniaturization. In this study, an improved flexible TENG with a tile‐nanostructured MXene/polymethyl methacrylate (PMMA) composite electrode (MP‐TENG) is proposed for use in wireless human health monitor. The multifunctional tile‐nanostructured MXene/PMMA film, which is self‐assembled through vacuum filtration, exhibits good conductivity, excellent charge capacity, and high flexibility. Thus, the MXene/PMMA composite electrode can simultaneously function as a charge‐generating, charge‐trapping, and charge‐collecting layer. Furthermore, the charge‐trapping capacity of a tile nanostructure can be optimized on the basis of the PMMA concentration. At a mass fraction of 4% PMMA, the MP‐TENG achieves the optimal output performance, with an output voltage of 37.8 V, an output current of 1.8 μA, and transferred charge of 14.1 nC. The output power is enhanced over twofold compared with the pure MXene‐based TENG. Moreover, the MP‐TENG has sufficient power capacity and durability to power small electronic devices. Finally, a wireless human motion monitor based on the MP‐TENG is utilized to detect physiological signals in various kinematic motions. Consequently, the proposed performance‐enhanced MP‐TENG proves a considerable potential for use in health monitoring, telemedicine, and self‐powered systems.

Exploiting Self-Healing Characteristics of Poly(methyl methacrylate) in Gel Electrolyte for Application in Electrochromic Devices

Self-healing characteristics in a gel electrolyte (GE) are desirable to improve the optical performance and service life of an electrochromic device (ECD). By exploiting the healing properties of poly(methyl methacrylate) (PMMA), the fabrication and characterization of GE with self-healing capabilities are reported here. Comparative mechanical and electrochemical analyses of the original and healed GE samples are performed to determine the optimum PMMA concentration and healing time. Experimental results show that the GE with 15 wt % of PMMA (GE15) recovers 98% of its mechanical strength within 10 min of healing time. The ionic conductivities of the healed samples are found to be the same as that of the original sample at all PMMA concentrations and healing times. It is observed that the healing time, viscosity, number of uncoiling polymer chains, and mobility of Li+ ions critically influence the healing efficiency of a GE. Color contrast analyses of ECDs fabricated with original and healed GEs are performed to demonstrate the applicability of self-healable GEs. It is recorded that for longer healing times the color performances of self-healed ECDs approach that of the original ECD. The findings of the present study will help to develop repair strategies for ECDs and improve their service life.

Preparation of PVDF/PMMA composite membrane with green solvent for seawater desalination by gap membrane distillation

With the increasing demand for freshwater, desalination of seawater and its alternatives has become a major priority for the scientific community. This work studied the preparation of a flat-sheet poly(vinylidene fluoride) (PVDF)/poly(methyl methacrylate) (PMMA) composite membrane by non-solvent induced phase separation (NIPS) for desalination using membrane distillation. The casting dope comprises PVDF, PMMA, and dimethyl sulfoxide (DMSO) in accordance with the green chemistry principle. The effect of PMMA content ranging from 3.6 wt% to 14.4 wt% in the casting dope on the membrane morphologies and characteristics was investigated. For a better understanding of membrane distillation, the performance of air gap membrane distillation (AGMD) and water gap membrane distillation (WGMD) at different feed temperatures (50–70 °C), flow rates (0.4–0.8 L/min), and gap widths (∼0, 1, 3 mm) were analyzed. Additionally, the advantages and disadvantages of DCMD and WGMD were evaluated using the permeate flux and gained output ratio (GOR). According to the results of the experiments, with an increase in PMMA content, the pore size, porosity, and contact angle of the membrane increased while the thickness of the skin layer decreased. In addition, the permeate fluxes were found to be greater in WGMD than in AGMD due to the higher thermal conductivity of water relative to air. The flux of membrane distillation increased as the gap width decreased and the feed temperature and flow rate increased. The highest flux of WGMD is 26.04 L m−2 h−1 when the feed temperature is 70 °C, the flow rate is 0.8 L/min, and the gap width is ∼0 mm. With optimal operating conditions, the as-prepared membrane showed potential for desalination, offering a viable solution to water stress concerns.

Phase Behavior of NR/PMMA Semi-IPNs and Development of Porous Structures

In this research, the porous polymer structures (IPN) were made from natural isoprene rubber (NR) and poly(methyl methacrylate) (PMMA). The effects of molecular weight and crosslink density of polyisoprene on the morphology and miscibility with PMMA were determined. Sequential semi-IPNs were prepared. Viscoelastic, thermal and mechanical properties of semi-IPN were studied. The results showed that the key factor influencing the miscibility in semi-IPN was the crosslinking density of the natural rubber. The degree of compatibility was increased by doubling the crosslinking level. The degree of miscibility at two different compositions was compared by simulations of the electron spin resonance spectra. Compatibility of semi-IPNs was found to be more efficient when the PMMA content was less than 40 wt.%. A nanometer-sized morphology was obtained for a NR/PMMA ratio of 50/50. Highly crosslinked elastic semi-IPN followed the storage modulus of PMMA after the glass transition as a result of certain degree of phase mixing and interlocked structure. It was shown that the morphology of the porous polymer network could be easily controlled by the proper choice of concentration and composition of crosslinking agent. A dual phase morphology resulted from the higher concentration and the lower crosslinking level. This was used for developing porous structures from the elastic semi-IPN. The mechanical performance was correlated with morphology, and the thermal stability was comparable with respect to pure NR. Investigated materials might be interesting for use as potential carriers of bioactive molecules aimed for innovative applications such as in food packaging.

The impact of adding PMMA to flexible conducting membrane of PVDF/ /Fe3O4

Flexible conducting membranes are very efficient in flexible wearable devices, smart devices, EMI shielding, energy storage material and artificial skin. A conductive membrane having good conductive property makes it effective for applications in flexible devices and smart devices. The paper here deals with the analysis of electrical parameters such as dielectric constant, conductive and dissipation factor of the fabricated membrane of Polyvinylidene fluoride (PVDF)/Ferrous Ferric Oxide (Fe3O4)/ PMMA for a range of frequency varying between 20 Hz and 10 MHz. To date the combination of PVDF/Fe3O4 showed good dielectric property but by addition of PMMA to this combination enhanced the conductivity to 10-5 and showed good dielectric property. Impedance analyser was utilized for measuring the various electrical parameters. The parameters emphasis on dielectric constant, AC conductivity and dissipation factor. The proposed paper concludes that on adding 0.8 gm of PMMA to 1 gm solution of PVDF/Fe3O4 (S3) provides the best result of the best results of conductivity, dielectric constant. PMMA content has a significant impact on proposed membrane properties including conductivity and dielectric property, and conductivity. The properties like conductivity increases with increasing PMMA level.

Characterization of Polymer Composites between Stereocomplex Polylactide Blends with Poly (methyl methacrylate)

Polylactide stereocomplex (ST) of poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA) (PLLA:PDLA 50:50) was blended with poly(methyl methacrylate) (PMMA) 10 – 50 wt.%. The materials were dissolved in chloroform at room temperature and the films were then cast. Differential scanning calorimetry showed a stereocomplex melting peak at 208 °C – 50 °C higher than that for neat PLLA or PDLA - confirming the polylactide stereocomplex crystallites. The PMMA content ratio of 10 – 50 wt.% in the stereocomplex showed almost complete stereocomplex crystallites. A peak at about 908 cm-1 in Fourier transform infrared spectra further confirmed the stereocomplex crystallites which indicated that PMMA could blend and efficiently bond with the stereocomplex. The X-ray diffraction analysis showed that the stereocomplex crystallinity became smaller when PMMA was added. Morphology from scanning electron microscopy revealed that phases separated in the ST/PMMA blend when the amount of PMMA was increased. Adding PMMA to stereocomplex films led to an increased elongation at break which peaked at 30 % added PMMA. Increased PMMA also led to the improved thermal stability of the stereocomplex. These properties and higher toughness are also needed in common applications, in particular films for packaging and protection of manufactured products.

Exploiting Partial Solubility in Partially Fluorinated Thermoplastic Blends to Improve Adhesion during Fused Deposition Modeling.

This work studies the effect of interlayer adhesion on mechanical performance of fluorinated thermoplastics produced by fused deposition modeling (FDM). Here, we study the anisotropic mechanical response of 3D-printed binary blends of poly (vinylidene fluoride) (PVDF) and poly (methyl methacrylate) (PMMA) with the isotropic mechanical response of these blends fabricated via injection molding. Various PVDF/PMMA filament compositions were produced by twin-screw extrusion and, subsequently, injection-molded or 3D printed into dog-bone shapes. Specimen mechanical and thermal properties were evaluated by mode I tensile testing and differential scanning calorimetry, respectively. Results show that higher PMMA concentration not only improved the tensile strength and decreased ductility but reduced PVDF crystallization. As expected, injection-molded samples revealed better mechanical properties compared to 3D printed specimens. Interestingly, 3D printed blends with lower PMMA content demonstrated better diffusion (adhesion) across interfaces than those with a higher amount of PMMA. The present study provides new findings that may be used to tune mechanical response in 3D printed fluorinated thermoplastics, particularly for energy applications.

Thermo-responsive programmable shape memory polymer based on amidation cured natural rubber grafted with poly(methyl methacrylate)

This work proposes a facile and new approach that uses graft copolymerization and amidation reaction to prepare shape memory polymer (SMP) based on natural rubber (NR). The poly(methyl methacrylate) modified NR (MGNR) is cross-linked with diamine through an amidation reaction. In this kind of approach, a novel type of cross-linked MGNR with a three-dimensional network of amide linkage was prepared. The solvent resistance, mechanical properties, and phase morphology of MGNRs were significantly improved after being cross-linked by a diamine cross-linker. Additionally, the cross-linked MGNR40 also exhibited excellent shape fixation and shape recovery. This is a direct result of the vitrification of the grafted PMMA domains at low temperatures, preventing elastic recovery. Meanwhile, a cross-linked network from amide linkage facilitates recovery force upon heating. Hence, the shape memory performance of MGNRs can be tuned with both grafted PMMA content and the degree of diamine cross-link. The strategy in this research work offered an effective and convenient method to obtain cross-linked MGNR with unique molecular architecture. Consequently, this cross-linked MGNR delivered excellent mechanical strength and shape memory performance.

Preparation of graded materials for miscible polycarbonate/poly(methyl methacrylate) blends by segregation under shear flow

AbstractExposure to shear flow produced by a pressure‐driven capillary rheometer provides a concentration gradient without phase separation in miscible polymer blends of bisphenol‐A polycarbonate containing low‐molecular‐weight poly(methyl methacrylate) (PMMA). The strand surface extruded from the rheometer contains a large amount of PMMA. However, the strand is transparent because there is no light scattering due to phase separation. The segregation behavior, that is, enrichment of the PMMA content at the strand surface, is enhanced when the molecular weight of PMMA is low. Furthermore, the segregation is also enhanced at high temperatures and at high shear rates. By contrast, the die length barely affects the degree of segregation. The segregation phenomenon should be noted because it may facilitate the modification of the surface properties of various products.