Carbonyl Groups Of PMMA Research Articles

Step-Wise Optimization Study for Modified Cellulose Nanocrystals as an Additive for Poly(Methyl Methacrylate) Composite Membranes

The cellulose nanocrystals (CNC)/Poly (methyl methacrylate) (PMMA) composite membranes were prepared by the solution casting method. The POM and SEM images indicated that the dispersibility of the composite membranes with chemical modification was better than that with physical modification. Moreover, the glass temperature of the composite membranes with chemical modification reduced remarkably compared to the neat PMMA. The mechanical properties characterization drew the same conclusion as the results of DSC. TGA results showed that the thermal properties of the nanocomposites have been enhanced due to hydrogen bonding interactions between the hydroxyl groups of CNC and the carbonyl groups of PMMA.

Nanofiber induced enhancement of electrical and electrochemical properties in polymer gel electrolytes for application in energy storage devices

In this article, a significant study on ionic conduction properties of novel nanocomposite polymer gel electrolytes (NCPGEs) is carried out using poly (methyl methacrylate) (PMMA) with nanofibers of silica (SiO2) complexed with lithium perchlorate (LiClO4) by combining experimental work and computational modelling. The compositional variation of SiO2 nanofibers in polymer electrolytes induces a visible alteration in different characteristics like ionic conductivity, electrochemical stability, interfacial stability, surface morphology and optical properties. Among all the compositions, NCPGEs containing 5 wt% nanofibers exhibit maximum ionic conductivity of 4.6 × 10−3 Scm−1 at room temperature. Fourier Transform Infrared Spectroscopy (FTIR) has shown a better interaction between lithium ions (Li+) with carbonyl group of PMMA in presence of SiO2 nanofibers. X-ray photoelectron spectroscopy (XPS) has confirmed various interactions among different constituents in NCPGEs. A combined molecular dynamics (MD) simulation and density functional theory (DFT) show a stable interaction between polymer with nanofiber filler and Li salt.

Coupling effect of pressure and flow fields on the crystallization of Poly(vinylidene fluoride)/Poly(methyl methacrylate) miscible blends

During polymer processing, the polymeric blends are inevitably subjected to coupled external fields (flow, pressure, and temperature), which have great effects on the phase behavior, crystallization behavior, crystalline structure, and final properties of blends. A typical crystalline/amorphous miscible blend system, poly(vinylidene fluoride)/Poly(methyl methacrylate) (PVDF/PMMA) blend, is chosen to understand the coupling effect of processing fields on crystallization behavior of the blends. It is found that shear flow can induce locally oriented trans conformation, which finally transforms into polar β/γ phases during isothermal crystallization under pressure. Interestingly, under pressure, β and γ phases exhibit different sensitivities to shear rate. The γ phase is easily formed at low shear rate, while higher shear rate is required to induce β phase formation, which could be related to the sequence length of the oriented trans conformation induced by shear flow. As for the addition of PMMA, the hydrogen bonding interactions between carbonyl groups of PMMA and hydrogen atom of PVDF could stabilize the shear-induced local trans conformation and subsequently lead to more β/γ phases. Meanwhile, different from PVDF crystallized under static condition, the shear flow and PMMA synergistically induce the transformation from spherulitic to shish-kebab-like structure and highly oriented thick β phase with higher melting point. To the best of our knowledge, it is the first time to reveal the unique crystallization behaviors of PVDF/PMMA blends induced by flow field coupled with pressure. This work could provide a significant guidance for the control of crystal polymorphs of PVDF/PMMA miscible blends during processing.

Effect of tacticity of poly(methyl methacrylate) on interfacial region with silica in polymer nanocomposite

AbstractThe effect of tacticity on the interfacial region between poly(methyl methacrylate) (PMMA) and silica in a PMMA/silica nanocomposite was investigated by differential scanning calorimetry (DSC), Fourier‐transform infrared spectroscopy (FT‐IR), and X‐ray diffraction (XRD). The glass transition temperature (Tg) values of the syndiotactic (st‐) and atactic (at‐) PMMA/silica nanocomposites are higher than those of the neat PMMA. Conversely, the Tg of the isotactic (it‐) PMMA/silica nanocomposite is slightly higher than that of the neat it‐PMMA. DSC and XRD results suggest that the restriction of the PMMA chain mobility in the silica nanoparticle interfacial region heightens as the syndiotactic content increases. FT‐IR results show that this phenomenon is caused by the interaction between the carbonyl group of PMMA and the silanol group on the silicon dioxide surface. Therefore, it can be concluded that the syndiotactic‐rich PMMA has a significantly different molecular mobility from that of the neat PMMA in the interfacial region with silica nanoparticle surface than isotactic‐rich PMMA.

Sequential Infiltration Synthesis of Electronic Materials: Group 13 Oxides via Metal Alkyl Precursors

The sequential infiltration synthesis (SIS) of group 13 indium and gallium oxides (In2O3 and Ga2O3) into poly(methyl methacrylate) (PMMA) thin films is demonstrated using trimethylindium (TMIn) and trimethylgallium (TMGa), respectively, with water. In situ Fourier transform infrared (FTIR) spectroscopy reveals that these metal alkyl precursors reversibly associate with the carbonyl groups of PMMA in analogy to trimethylaluminum (TMAl), however, with significantly lower affinity. This is demonstrated to have important kinetic consequences that dramatically alter the synthetic parameters required to achieve material growth. Ab initio density functional theory simulations of the methyl methacrylate monomer with group 13 metal alkyls corroborate association energy that is 3× greater for TMAl than for either TMIn or TMGa. As a consequence, the kinetics of activated diffusion within the film is observed to be far more rapid for TMIn and TMGa than for TMAl. Spectroscopic ellipsometry and scanning electron micros...

Aggregation States of Polymers at Hydrophobic and Hydrophilic Solid Interfaces

Aggregation states of polystyrene (PS) and poly(methyl methacrylate) (PMMA) at hydrophobic deuterated-octadecyltrichlorosilane (OTS-d) and hydrophilic SiOx interfaces are discussed, focusing on the interaction strength between polymer and substrate. Sum-frequency generation spectroscopy revealed that PS exhibited oriented phenyl groups along the normal direction at the interface in a spin-coated film because of the centrifugal force generated during the film solidification process, whereas it did not in a solvent-cast film. This result was common for both hydrophobic and hydrophilic substrates. That is, the aggregation states of PS depended little on which kind of substrate was used. This is because the interaction between PS and the surfaces is weak. In the case of a PMMA film on the hydrophobic OTS-d substrate, the interfacial local conformation was also dependent on the method of film preparation. PMMA at the hydrophilic SiOx interface, however, exhibited oriented ester methyl groups along the direction normal to the interface, regardless of the film preparation method. This is due to a stronger interaction via hydrogen bonding between carbonyl groups of PMMA and the substrate surface.

Dehydrogenation mechanism of LiBH4 by Poly(methyl methacrylate)

We investigated the dehydrogenation properties and mechanism of Poly(methyl methacrylate) (PMMA) confined LiBH4. Thermal stability of LiBH4 was reduced by PMMA, with a decrease in dehydrogenation temperature by 120°C. At 360°C, the composite showed fast dehydrogenation kinetics with 10wt.% of hydrogen released within 1h. The improved dehydrogenation performance was mainly attributed to the reaction between LiBH4 and PMMA forming Li3BO3 as a final product. Furthermore, the presence of electrostatic interaction between B atom of LiBH4 and O atom in the carbonyl group of PMMA may weaken the BH bonding of [BH4]− and lower the hydrogen desorption temperature.

Evaluation of enthalpy of mixing by calorimetric method: effect of hydrogen bonding in poly(4-hydroxy styrene)-based blends

To verify the effect of hydrogen bonding on the polymer mixing, blends of poly(vinyl methyl ether) (PVME) and poly(methyl methacrylate) (PMMA) with poly(4-hydroxy styrene) (PHS), respectively, have been prepared. The effect of hydrogen bond strength on the enthalpy of mixing, ΔHM, was investigated by microcalorimetric measurements and FTIR spectroscopy. Infrared analysis allowed to measure the amount of hydrogen bonding by a curve fitting procedure in PHS/PMMA blends, looking to the change in the characteristic bands of carbonyl group of PMMA. In the case of PHS/PMVE, the hydroxyl-stretching region has been investigated to have only a qualitative estimation of hydrogen bonding. For both PHS/PMVE and PHS/PMMA systems, the measured exothermic (negative) ΔHM decreases with the increase in the PHS content, indicating that the presence of strong specific intermolecular interactions, such as hydrogen bonding, favours the polymer blending.

Proton conductivity and fuel cell performance of organic–inorganic hybrid membrane based on poly(methyl methacrylate)/silica

Organic–inorganic hybrid membranes based on poly(methyl methacrylate) (PMMA)/silica have been synthesized using a sol-gel technique for use in polymer electrolyte fuel cells (PEFCs). The properties of these membranes were characterized using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and thermogravimetric analysis. The results indicate that these membranes are formed through hydrogen bonds between the carbonyl group of PMMA and the uncondensed alcohol functional groups of the inorganic clusters. The proton conductivity of these membranes is on the order of 10−1 S cm−1, and the 60PMMA–30SiO2–10P2O5 membrane displays the highest proton conductivity of 3.85 × 10−1 S cm−1 at 90 °C and 50% RH. The performance of a fuel cell using these membranes was tested. A maximum power density of 370 mW cm−2 is obtained at 80 °C, and the current density at 0.4 V remains almost unchanged during the 100-h test time under the test conditions. This class of hybrid membranes is an extremely promising material for use in PEFCs.

Structures and morphologies of in situ polymerized blends of PMMA and ASA

AbstractBlends of poly(methyl methacrylate), PMMA, and the elastomer ASA, a graft copolymer based on poly(acrylonitrile‐co‐styrene) (SAN) and acrylic rubber, were prepared by in situ polymerization and characterized according to structural, mechanical, thermal, and morphological properties. The polymerization conditions, such the presence or absence of a chain transfer agent, stirring and an inert atmosphere, influence the morphological and structural properties of the blends. In spite of the evidences of the partial miscibility between PMMA and SAN phase of the ASA, the blends are heterogeneous and present a complex morphology. The morphology of some PMMA‐ASA blends is made up of an elastomeric dispersed phase in a glassy matrix, with a possible inclusion of the matrix in the elastomeric domains. The selective extraction of the blend components and infrared spectroscopy showed that crosslinking and/or grafting reactions occur on ASA chains during MMA polymerization. The syndiotacticity of PMMA obtained in the presence of ASA increases with the amount of ASA, due to possible interactions between the carbonyl groups of PMMA and the nitrile or phenyl groups of the SAN copolymer. The mechanical properties of the blends were influenced by the compositions of the blends and mainly by the conditions of polymerization. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Hydrogen bond interaction and dynamics in PMMA/PVPh polymer blends as revealed by advanced solid-state NMR

The hydrogen bond interactions and dynamics of the poly (methyl methacrylate) (PMMA) and poly (4-vinyl phenol) (PVPh) polymer blends were studied by a variety of advanced solid-state NMR techniques. The possible hydrogen bond interactions between the carbonyl group of PMMA and hydroxyl group of PVPh were successfully elucidated by two-dimensional 1H–1H spin-exchange 13C–1H heteronuclear chemical-shift correlation (HETCOR) NMR experiment. The 13C 2D separation of undistorted powder patterns by effortless recoupling (SUPER) experiments combined with quantum chemical calculations for the theoretical predictions of chemical-shift anisotropy (CSA) parameters were utilized to investigate the intermolecular hydrogen-bonding interactions and molecular conformation of the blends. 13C–1H PISEMA (polarization inversion and spin-exchange at magic angle) experiments at different temperatures were used to reveal the heterogeneous dynamics resulting from the cooperative motion associated with the hydrogen bond interaction. PISEMA analysis shows that the motion of aromatic group in PVPh is affected by the rotating motions of methyl in PMMA.

Thermal degradation of organophosphorus flame-retardant poly(methyl methacrylate) nanocomposites containing nanoclay and carbon nanotubes

Filler nanoparticles pave the way for the development of novel halogen-free flame-retardant polymers. The aim of this study was to investigate the thermal degradability, and in particular, the thermal degradation mechanism of organophosphorus flame-retardant poly(methyl methacrylate) (PMMA) nanocomposites containing nanoclay (NC) and multi-walled carbon nanotubes (CNT). For this purpose, thermogravimetry and direct pyrolysis mass spectrometry analysis were utilized. The onset of degradation was delayed through increased maximum degradation temperature and suppressed mass loss corresponding to initial degradation stage with carbon nanotubes and nanoclays, respectively. Possibility of reactions of melamine and/or melamine derivatives and interactions between carbonyl groups of PMMA and phosphinic acid leading to thermally more stable products was increased owing to the barrier effect of filler nanoparticles. In the presence of NC better flame retarding characteristics was detected as anhydride formation, leading to charring being more effective.

Size effect of silica nanoparticles on thermal decomposition of PMMA

The size effect of silica nanoparticles (SiO2) on thermal decomposition of poly(methylmethacrylate) (PMMA) was investigated by the controlled rate thermogravimetry. Thermal degradation temperature of PMMA–SiO2 composites depended on both fraction and size of SiO2, the thermal degradation temperature of 23 nm (diameter) SiO2–PMMA (6.1 wt%) was 13.5 °C higher than that of PMMA. The thermal stabilities of 17 nm SiO2–PMMA (3.2 wt%) and 13 nm SiO2–PMMA (4.8 wt%) were 21 and 23 °C, respectively, higher than that of PMMA without SiO2. The degree of degradation improvement was increased linearly with the surface area of SiO2. The number of surface hydroxyl group in unit volume of SiO2 particle increased with increasing the specific surface area of SiO2, and the interaction between hydroxide group of SiO2 and carbonyl group of PMMA had an important role to improve the thermal stability of PMMA.

Investigation of the structural, thermal, mechanical, and optical properties of poly(methyl methacrylate) and poly(vinylidene fluoride) blends

AbstractIn this investigation, poly(methyl methacrylate) (PMMA) and poly(vinylidene fluoride) (PVDF) blends (w/w) were prepared in a Brabender (South Hackensack, NJ) plasticorder with a thermoplastic mixing chamber (type W60) preheated at 180°C. These blends were further converted into films by a conventional solution casting method and characterized with Fourier transform infrared spectroscopy, differential scanning calorimetry, X‐ray diffraction, mechanical property measurements, impact strength testing, ultraviolet–visible spectroscopy, refractive‐index measurements, and contact‐angle study. The Fourier transform infrared results indicated that the compatibility between these two systems resulted from hydrogen bonding between the carbonyl group of PMMA and the CH2 group of PVDF. The thermal analysis showed depressions in the glass‐transition temperature, melting temperature, and crystallization temperature. The heat of crystallization increased with an increase in the PVDF content in the blend. An increase in the heat of crystallization meant an increase in the crystallinity. An increase in the cooling rate increased the crystallization rate. The improvement in the mechanical properties of the blend films indicated that the observed behavior was ascribable to a more coherent structure of the blends due to strong specific interactions between PMMA and PVDF chains. The impact strength analysis revealed a substantial increase in the impact strength from 21.64 to 38.52 J/m. Optical absorption spectra suggested the presence of an optical band gap energy that increased with an increase in the PVDF content in the blend. The contact angle against water increased with the PVDF content in the blend film, and this was caused by the hydrophobicity of PVDF due to the CF2 group of PVDF. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Effect of PMMA addition on characterization and morphology of PVDF

AbstractPolyvinylidene fluoride and polymethylmethacrylate (PVDF/PMMA) films were blended with different concentrations by casting method. Structural, spectroscopic, and morphological characteristics of both the interface and the surface of the films have been investigated. The blends were characterized using X‐ray diffraction (XRD), Fourier transform infrared (FTIR), UV–visible, differential thermal analysis (DTA), and scanning electron microscopy (SEM). All measurements reveal that the blends take place based on the influence of PMMA content on PVDF. FTIR results indicate the possible interactions between carbonyl group of PMMA and CH2 groups of PVDF which indicates the formation of blends. Optical absorption spectra suggested the presence of an optical gap (Eg) which decreased with increasing PMMA content. UV/VIS spectra were characterized by a sharp edge and a window of wavelength range 290–350 nm for some blends. The optical window can be used as an optical sensor or band pass filter. The degree of crystallinity was found to decrease with increasing PMMA content, which was confirmed by XRD and DTA analysis. SEM micrograph shows spherulites which increase with the addition of PMMA and it becomes sharper and contains a longitudinal shape. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers

Interfacial structure of poly(methyl methacrylate)/TiO2 nanocomposites prepared through photocatalytic polymerization

AbstractPoly(methyl methacrylate)/TiO2 nanocomposites have been prepared by the polymerization with photoexcited TiO2 nanoparticles as initiator. To reveal the interfacial structure, the composites obtained are investigated by FTIR and XPS analysis. The bound PMMA displays triply split IR bands attributed to the carbonyl stretching mode, meanwhile great changes also occur in the IR range closely related to the conformation of PMMA. Based on the area of the nonassociated and associated PMMA carbonyl stretching peaks in the FTIR spectrum, it is calculated out that the bound PMMA is constituted of 70% repeating units in nonassociated state and 30% units associated to TiO2 inorganic nanoparticles. Moreover, XPS analysis show that Ti2p doublet of the composites shift to lower binding energy by 1.0 eV, indicating the interaction between Ti atoms of TiO2 and oxygen atoms of PMMA. According to the observation that the interaction involves both carboxyl and carbonyl groups of PMMA, a bidentate complex is approved. In addition, compared with the extracted PMMA, certain backbone chains of bound PMMA have to change their rotational conformations from gauche to trans so as to bond to the surface active centers at TiO2 nanoparticles. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Intercalation of poly(methyl methacrylate) into tyramine-modified layered silicates through hydrogen-bonding interaction

Layered silicates modified with tyramine hydrochloride (HOC6H4CH2NH3+Cl-) were prepared and subsequently used in the preparation of polymer–layered silicate nanocomposites. Accordingly, surfaces of tyramine-modified silicate layers are partially covered with the phenol groups, which are able to form hydrogen bonds with the carbonyl groups of PMMA. In this study the solution-mediated process was applied to prepare two PMMA-based nanocomposites from tyramine-modified montmorillonite and Laponite (TAMMT and TALAP). Through hydrogen bonding, PMMA molecules are absorbed onto the silicate surfaces, and hence silicate layers can be dispersed in the polymer matrix. In the case of using TAMMT whose size is 300–500nm, the intercalated nanocomposite is obtained. While using TALAP which has the much smaller diameter (25–50nm) compared to TAMMT, the corresponding nanocomposite exhibits a mixed intercalated/exfoliated morphology. The nano-morphology of the nanocomposites was characterized by means of X-ray diffraction and TEM. FTIR was used to verify the presence of hydrogen bonds between PMMA and the surface phenol groups, and in addition, the interaction between PMMA and the surface oxygens of silicates.

Free volume microprobe studies on poly(methyl methacrylate)/poly(vinyl chloride) and poly(vinyl chloride)/polystyrene blends

AbstractBlends of Poly(methyl methacrylate) (PMMA)/Poly(vinyl chloride) (PVC) and Poly(vinyl chloride) (PVC)/Polystyrene (PS) of different compositions were prepared by solution casting technique. The blends were characterized using Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR), and Positron Lifetime Spectroscopy. DSC data were found to be inadequate to describe whether PMMA/PVC blends are miscible or not, possibly because of the small gap in their glass transition temperatures. On the other hand, PVC/PS blends were clearly found to be immiscible by DSC. FTIR results for PMMA/PVC indicate the possible interactions between the carbonyl group of PMMA and α‐hydrogen of PVC. Free volume data derived from Positron lifetime measurements showed that the PMMA/PVC blends to be miscible in low PVC concentration domain. For the first time, the authors have evaluated the hydrodynamic interaction parameter α, advocated by Wolf and Schnell, Polymer, 42, 8599 (2001), to take into account the friction between the component molecules using the free volume data. This parameter (α) has a high value (−57) at 10 wt% of PVC, which could be taken to read miscibility for PMMA/PVC blends to be high. In the case of PVC/PS blends, the positron results fully support the DSC data to conclude the blends to be immiscible throughout the range of concentration. As expected, the hydrodynamic interaction parameter α does not show any change throughout the concentration in PVC/PS blends, further supporting the idea that α is another suitable parameter in the miscibility study of polymer blends. POLYM. ENG. SCI., 46:1231–1241, 2006. © 2006 Society of Plastics Engineers

Miscibility of poly(vinylidene fluoride) and atactic poly(methyl methacrylate)

AbstractDifferent results for the miscibility between poly(vinylidene fluoride) (PVDF) and atactic poly(methyl methacrylate) (at‐PMMA) have been reported. In this study, the interaction between PVDF and at‐PMMA was confirmed, although such a kind of force was weak. With increasing PVDF weight fraction, the blends exhibited more heterogeneous properties, and the films thus appeared more opaque. The difference spectra after subtraction of PVDF and poly(methyl methacrylate) (PMMA) showed that the interaction between the carbonyl groups of PMMA and the hydrogen atoms of PVDF increased as the stretch vibration of CO bonds band shifted to a lower frequency with higher PVDF content. From the computer analysis, the sum spectra of the blends could not be obtained by simple addition of the separate spectra of the homopolymers. The contact angle measurement demonstrated that the hydrophobicity against water increased with PVDF content and that contact angles against water were larger than 90° when the PVDF content exceeded 30%, indicating good water repellency. The contact angles against n‐hexane, however, could not be measured because of the complete wetting of the film by n‐hexane. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1–5, 2004

Thermal behavior and specific interaction in high glass transition temperature PMMA copolymer

A series of high glass transition temperature copolymers based on poly(methyl methacrylate) (PMMA) were prepared by free radical copolymerization of methacrylamide and methyl methacrylate monomers in dioxane solvent. The thermal properties and hydrogen-bonding interactions of these poly(methacrylamide-co-methyl methacrylate) (PMAAM-co-PMMA) copolymers with various compositions were investigated by differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, and solid-state nuclear magnetic resonance (NMR) spectroscopy. A large positive deviation in the behavior of Tg, based on the Kwei equation from DSC analyses, indicates that strong hydrogen bonding exists between these two monomer segments. The FTIR and solid-state NMR spectroscopic analyses give positive evidence for the hydrogen-bonding interaction between the carbonyl group of PMMA and the amide group of PMAAM (e.g. by displaying significant changes in chemical shifts). Furthermore, the proton spin–lattice relaxation time in the rotating frame (T1ρ(H)) has one single value over the entire range of compositions of copolymers, and gives a value shorter than the average predicted. The proton relaxation behavior indicates the rigid nature of the copolymer.