In situ intercalative polymerization of poly(methyl methacrylate)/clay nanocomposites by γ-ray irradiation

Poly(methyl methacrylate) (PMMA)/clay nanocomposites was prepared by in situ intercalative polymerization initiated by γ-ray irradiation. The degree of dispersion and the intercalation spacing of these nanocomposites were investigated with the X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM), respectively. The thermal stabilities of the samples were studied by the thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC).     

Effects of modified Clay on the morphology and thermal stability of PMMA/clay nanocomposites

The potential to improve the mechanical, thermal, and optical properties of poly(methyl methacrylate) (PMMA)/clay nanocomposites prepared with clay containing an organic modifier was investigated. Pristine sodium montmorillonite clay was modified using cocoamphodipropionate, which absorbs UVB in the 280–320 nm range, via ion exchange to enhance the compatibility between the clay platelets and the methyl methacrylate polymer matrix. PMMA/clay nanocomposites were synthesized via in situ free-radical polymerization. Three types of clay with various cation-exchange capacities (CEC) were used as inorganic layered materials in these organic–inorganic hybrid nanocomposites: CL42, CL120, and CL88 with CEC values of 116, 168, and 200 meq/100 g of clay, respectively. We characterized the effects of the organoclay dispersion on UV resistance, effectiveness as an O₂ gas barrier, thermal stability, and mechanical properties of PMMA/clay nanocomposites. Gas permeability analysis demonstrated the excellent gas barrier properties of the nanocomposites, consistent with the intercalated or exfoliated morphologies observed. The optical properties were assessed using UV–Visible spectroscopy, which revealed that these materials have good optical clarity, UV resistance, and scratch resistance. The effect of the dispersion capability of organoclay on the thermal properties of PMMA/clay nanocomposites was investigated by thermogravimetric analysis and differential scanning calorimetry; these analyses revealed excellent thermal stability of some of the modified clay nanocomposites.     

Characterization and properties of in situ emulsion polymerized poly(methyl methacrylate)/graphene nanocomposites

Poly(methyl methacrylate) (PMMA)/graphene nanocomposites were prepared by in situ emulsion polymerization. Raman and Fourier transform infrared spectra showed that PMMA polymer contained partially reduced graphite oxide. Dynamic mechanical analysis and differential scanning calorimetry analysis showed that graphene in the PMMA matrix acted as reinforcing filler; it enhanced the storage moduli and glass transition temperatures of the nanocomposites. Thermogravimetric analysis showed that the thermal stability of the nanocomposites increased by ca. 35 °C. The electrical conductivity of nanocomposite with 3 wt.% graphite oxide was 1.5 S m⁻¹ at room temperature.     

Preparation of poly(methyl methacrylate)/lanthanum hydroxide nanowire nanocomposites with improvement in thermal stability

Poly(methyl methacrylate) (PMMA)/lanthanum hydroxide (La(OH)₃) nanowire nanocomposites were prepared by in-situ polymerization of methyl methacrylate (MMA) in the DMF solution. The improvement in thermal stability of the nanocomposites is remarkable with low inorganic nanowires content. The experimental results indicate ultimate network formation for the nanocomposites is possibly through interaction between La³⁺ and MMA monomer during polymerization. The network induces the mobility restriction of polymer chains and greatly prevents polymer chains from decomposition. The characteristic of one-dimensional nanowires used here may play a key role in the formation of the “cross-link” network and decision of the low content of nanowires addition in the polymer matrix.     

Exfoliated poly(methyl methacrylate)/MgFe-layered double hydroxide nanocomposites with small inorganic loading and enhanced properties

The novel exfoliated polymer nanocomposites (PMMA/MgFe(DS)-LDH) were synthesized by in situ polymerization based on poly(methyl methacrylate) (PMMA) and dodecyl sulfate-intercalated MgFe-layered double hydroxide (MgFe(DS)-LDH). The participation of Fe³⁺ ion is found to play an important role in the improvement of thermal stability of nanocomposites with small inorganic loading and well-dispersed inorganic components. The thermal degradation mechanism was discussed.     

Transparent poly(methyl methacrylate)/ZnO nanocomposites based on KH570 surface modified ZnO quantum dots

Transparent luminescent ZnO embedded PMMA polymer has been synthesized by means of grafting poly(methyl methacrylate) (PMMA) onto the surface of ZnO QDs after g-methacryloxypropyl trimethoxy silane (KH570) modification. The resulting ZnO/PMMA nanocomposites with KH570-modified nanoparticles have better dispersibility and preserve the superior luminescence of ZnO nanoparticles in the nanocomposites. The obtained PMMA/ZnO nanocomposite films show high transparency, high UV-shielding efficiency and improved thermal stability. The obtained nanocomposite was characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope (TEM), X-ray powder diffraction (XRD), thermogravimetry (TG), ultraviolet-visible (UV-vis) absorption spectroscopy.     

Dispersion of nanoplatelets of graphite on PMMA matrix by in situ polymerisation technique

Poly(methyl methacrylate)/expanded graphite (PMMA/EG) composites were prepared by the incorporation of EG in various proportions (1%, 2%, 3%, 4% and 5%) with PMMA by in situ polymerisation technique. The polymer composites were characterised by ultraviolet–visible (UV–vis) and Fourier transform infra-red spectroscopies. The structural property of PMMA/EG nanocomposites was studied by X-ray diffraction. The scanning electron microscopy and transmission electron microscopy of synthesised composites were taken in order to study their morphological properties. The conductivity of composites was measured as function of EG concentration. It was found that conductivity of composites gradually increased with the increase in EG loading. Oxygen permeability of PMMA/EG nanocomposites was calculated and it was found that the property was reduced substantially with rise of EG proportion. The thermal stability of PMMA/EG nanocomposites was improved by dispersion of EG with PMMA matrix.     

Improved thermal properties of graphene oxide-incorporated poly(methyl methacrylate) microspheres

Graphene, a single layer of carbon atoms in a two-dimensional lattice, has attracted considerable attention owing to its unique physical, chemical and mechanical properties. In particular, because of its excellent thermal properties such as high thermal conductivity and good thermal stability, graphene has been regarded as a one of the promising candidates for the reinforcing fillers on the polymer composites field. In this study, we prepared the poly(methyl methacrylate) (PMMA)/graphene oxide (GO) nanocomposite by a simple solution mixing process, and examined the thermal reinforcing effects of GO on a PMMA matrix. Using thermogravimetric analysis, differential scanning calorimeter, and thermal conductivity meter, we investigated the effects of GO on the thermal properties of PMMA/GO nanocomposites. With 3 wt% of GO loading, the glass transition temperature (Tg) of the PMMA/GO nanocomposite were increased by more than 7 degrees C and the thermal conductivity of which also improved 1.8 times compared to pure PMMA.     

Preparation and characterization of poly(methyl methacrylate)-clay nanocomposites via melt intercalation: Effect of organoclay on thermal, mechanical and flammability properties

The PMMA nanocomposites were prepared by melt processing method. The influence of organoclay loading on extent of intercalation, thermal, mechanical and flammability properties of poly(methyl methacrylate) (PMMA)-clay nanocomposites were studied. Three different organoclay modifiers with varying hydrophobicity (single tallow vs. ditallow) were investigated. The nanocomposites were characterized by using wide angle X-ray diffraction, transmission electron microscopy, thermogravimetric analysis, differential scanning calorimetry (DSC), and tensile tests. The intercalation of polymer chain within the silicate galleries was confirmed by WAXD and TEM. Mechanical properties such as tensile modulus (E), tensile strength, percentage elongation at break and impact strength were determined for nanocomposites at various clay loadings. Overall thermal stability of nanocomposites increased by 16-17 °C. The enhancement in T_g of nanocomposite is merely by 2-4 °C. The incorporation of maleic anhydride as compatibilizer further enhanced all the properties indicating improved interface between PMMA and clay. The flammability characteristics were studied by determining the rate of burning and LOI.     

The intercalation of poly(methyl methacrylate)/aluminophosphate nanocomposites and the properties improvement

Poly(methyl methacrylate) (PMMA)/dodecylamine templated lamellar aluminophosphate (DDA-LAP) intercalated nanocomposites are prepared by in situ bulk polymerization of MMA. The intercalated structure is characterized. With the intercalation of DDA-LAP in PMMA matrix, the glass-transition temperatures of nanocomposites (T_g) are increased. The nanocomposites obtained keep relatively high transparency in optical property and have a significant improvement in mechanical properties and thermal stability. The mechanism for the properties enhancement is investigated. The strong interfacial interaction between the aluminophosphate layers and the PMMA chains, the homogeneously distribution and the graphitized char formation during heating are three key roles for the properties improvement.     

聚甲基丙烯酸甲酯/膨胀石墨纳米导电复合材料的制备与表征

通过原位插层聚合制备了聚甲基丙烯酸甲酯/膨胀石墨纳米导电复合材料,其室温导电渗滤阈值约为3%(质量分数),当膨胀石墨的质量分数为8%时,室温电导率可高达60 S/cm。通过TEM、SEM观察了复合材料的形貌,用DSC测定其热力学性能并探讨了不同外加电压对PMM A/膨胀石墨纳米导电复合材料体积电导率的影响,同时研究了复合材料的拉伸强度。     

Fabrication and characterization of carbon nanotube reinforced poly(methyl methacrylate) nanocomposites

Multiwall carbon nanotube (CNT) reinforced poly(methyl methacrylate) (PMMA) nanocomposites have been successfully fabricated with melt blending. Two melt blending approaches of batch mixing and continuous extrusion have been used and the properties of the derived nanocomposites have been compared. The interaction of PMMA and CNTs, which is crucial to greatly improve the polymer properties, has been physically enhanced by adding a third party of poly(vinylidene fluoride) (PVDF) compatibilizer. It is found that the electrical threshold for both PMMA/CNT and PMMA/PVDF/CNT nanocomposites lies between 0.5 to 1 wt% of CNTs. The thermal and mechanical properties of the nanocomposites increase with CNTs and they are further increased by the addition of PVDF For 5 wt% CNT reinforced PMMA/PVDF/CNT nanocomposite, the onset of decomposition temperature is about 17 degrees C higher and elastic modulus is about 19.5% higher than those of neat PMMA. Rheological study also shows that the CNTs incorporated in the PMMA/PVDF/CNT nanocomposites act as physical cross-linkers.     

Synthesis and characterization of TiO2/poly(methyl methacrylate) nanocomposites via surface thiol-lactam initiated radical polymerization

An approach to the surface modification of TiO2 nanoparticles was described based on the thiol functionalization of TiO2 followed by thiol-lactam initiated radical polymerization (TLIRP) of methyl methacrylate (MMA). FT-IR, XRD and XPS analyses confirmed the grafting of the polymer on the TiO2 surface. TGA analysis revealed superior thermal stability of PMMA-g-TiO2 compared with PMMA. TEM measurements and time-dependent phase monitoring suggested much higher colloidal stability of PMMA-g-TiO2 than TiO2 in toluene. The controlled nature of the TLIRP of MMA from the surface of TiO2 was determined by GPC analysis.     

Poly(methyl methacrylate)–TiO2 nanocomposites obtained by non-hydrolytic sol–gel synthesis: the innovative tert-butyl alcohol route

The present article concerns the preparation of poly(methyl methacrylate)/titania nanocomposites by a non-conventional bottom-up approach, as alternative to the conventional mechanical compounding of preformed filler particles. Poly(methyl methacrylate) (PMMA) was modified with in situ generation of titania nanoparticles by means of the so-called non-hydrolytic sol–gel (NHSG) process in the presence of tert-butyl alcohol (tBuOH) as oxygen donor and polymer solvent. The results showed that the synthetic procedure used permitted the preparation of the highly filled PMMA (up to 20 phr of titania in anatase form) with titania actual content values very close to the nominal ones and with enhanced filler dispersion and homogeneous distribution within the polymeric matrix, avoiding the typical rheological problems related to distributive and dispersive mixing of conventional compounding methods. The presence of titania nanoparticles led to increases in glass transition temperature and E′ modulus in the rubbery region for all the prepared samples with respect to the pristine PMMA. Finally, the nanocomposites showed an interesting photo-catalytic activity towards organic molecules. The findings led us to conclude that the NHSG process was successfully employed to produce anatase titania in the presence of tBuOH and PMMA. The proposed process seems to offer a very promising method to produce polymer nanocomposites with good filler dispersion and homogeneous distribution and with interesting functional properties such as photo-catalytic activity.     

Preparation and luminescent properties of GdOF:Ce,Tb nanoparticles and their transparent PMMA nanocomposites

GdOF:Ce, Tb nanoparticles and their poly (methyl methacrylate) (PMMA) nanocomposites have been successfully prepared by a thermolysis route and thermal polymerization of methyl methacrylate (MMA) monomer, respectively. The obtained nanoparticles and nanocomposites are characterized by XRD, EDS, TEM, FTIR, TGA, UV–Vis and PL spectrum. The as-synthesized transparent GdOF:Ce, Tb/PMMA nanocomposites exhibit green photoluminescence under the irradiation of 254 nm UV lamp due to the incorporation of luminescent GdOF:Ce, Tb nanoparticles into the PMMA matrix. The present route would provide a general strategy to prepare other functional nanocomposites.     

Thermo-mechanical properties of poly(vinylidene fluoride) modified graphite/poly(methyl methacrylate) nano composites

Poly(methyl methacrylate) (PMMA) nano composites were synthesized by melt compounding technique. Different graphite loadings were investigated, including some treated with poly(vinylidene fluoride) (PVDF). A homogeneous dispersion of graphite throughout the PMMA matrix was observed under microscopic analysis. Thermo-gravimetric analysis showed the incorporation of graphite resulted in improvement of thermal stability of neat PMMA. Dynamic mechanical thermal analysis also showed a significant improvement in the storage modulus over the temperature range of 25–150 °C. Coating the graphite with a small amount of PVDF was found to further extend the improvement in the modulus of the PMMA nano composite at 1 wt.% graphite loading.     

层离型PMMA/镁铁双氢氧化物纳米复合材料的热动力学

通过原位聚合法制备了以聚甲基丙烯酸甲酯为基体,与镁铁双氢氧化物具有良好相容性的层离型纳米复合材料。实验结果表明,MgFe-LDH的引入显著提高了聚合物的热解温度,两者间的相互作用和片层的物理阻隔都起到了作用。采用Flynn-Wall-Ozawa和Friedman法对体系进行热动力学分析,两种计算结果相互验证,表明纳米复合材料的热解表观活化能较纯样明显增大,热分解过程受到阻碍。这种热稳定化作用不仅与片层的物理阻隔有关,也应当与热解反应的能量阻隔有关。     

Thermal, mechanical and vibration characteristics of epoxy-clay nanocomposites

Diglycidyl ether of bisphenol-A (DGEBA) epoxy resin system filled individually with organoclay (OC) and unmodified clay (UC) were synthesized by mechanical shear mixing with the addition of diamino-diphenylmethane (DDM) hardener. The unmodified clay used was Na⁺-Montmorillonite (MMT) and the organoclay was alkyl ammonium treated MMT clay. The reinforcement effect of OC and UC in the epoxy polymer on thermal, mechanical and vibration properties were studied. X-ray diffraction (XRD) and Transmission electron microscopy (TEM) were used to study the structure and morphology of nanocomposites. Curing study shows that the addition of OC in epoxy resin aids the polymerization by catalytic effect, and UC addition does not show any effect in the curing behavior of epoxy polymer. Thermogravimetry analysis (TGA) shows enhanced thermal stability for epoxy with OC fillers than that of epoxy with UC fillers. The epoxy with OC fillers shows considerable improvement on tensile and impact properties over pure epoxy polymer and epoxy with UC fillers. The improvement in tensile and impact properties of nanocomposites is supported with the fracture surface studies. Epoxy with OC fillers shows enhanced vibration characteristics than that of the pure epoxy polymer and epoxy with UC fillers.     

Preparation,solubility, and electrorheological properties of carbon nanotubes/poly(methyl methacrylate) nanocomposites by in situ functionalization

Poly(methyl methacrylate) (PMMA) nanobeads-decorated multi-walled carbon nanotubes (MWNTs) and single-walled carbon nanotubes (SWNTs) nanocomposites were prepared using two processing steps. Initially, spherical PMMA nanoparticles were synthesized using an emulsion polymerization method. Afterward, the PMMA nanobeads were decorated to MWNTs and SWNTs using benzoyl peroxide as an initiator in water during a high temperature refluxing process. The results confirmed the linkage of the nanotubes to the surrounding PMMA nanobeads via a covalent bond. The resultant nanocomposites showed high solubility in chloroform without flocculation after 24 h. In addition, the nanotubes/PMMA nanocomposites were characterized by electrical resistance measurements to analyze their electrical conductivity and examined as electrorheological (ER) materials when dispersed in silicone oil.     

Thermal stability of PMMA-clay hybrids

Materials with small particle size are being extensively used in composites and hybrid materials. Exfoliated clay-polymer hybrids show enhanced properties. Exfoliation of clay platelets can be affected by selecting dispersing agents. In the present work, clay dispersed by natural dispersant (soap stone powder), cetyl trimethyl ammonium bromide (CTAB) dispersed clay and acid clay (amorphous clay) are taken. They are then polymerized with poly methyl methacrylate (PMMA) by solution intercalation method. The thermal stability of these different clay-PMMA hybrids have been studied and compared with that of pure PMMA by differential scanning calorimeter (DSC). The bonding of clay with PMMA has been studied by IR. Morphology of clay-PMMA hybrids has been shown by SEM and XRD which indicate partially exfoliated structure in T606-4 and intercalated structures in T606-6 and T606-2.