Biodegradation behaviour of PMMA/cellulose nanocomposites prepared by in-situ polymerization and ex-situ dispersion methods

The development of coatings that maintain the attractive natural appearance of wood while providing ultraviolet (UV) protection is extremely important for the widespread use of wood products. In this study, the influence of different types (powder form and aqueous dispersions) of TiO2 in an amount of 1.0 wt% by monomer weight on the properties of environmentally friendly polyacrylate (PA)/TiO2 emulsions prepared by ex situ and in situ polymerization, as well as on the UV-protective properties of the coating films, was investigated. The results showed that the addition of TiO2 significantly affected the particle size distribution of PA and the viscosity of PA varied according to the preparation method. Compared with the ex situ preparation method, in situ polymerization provides better dispersibility of TiO2 nanoparticles in PA coating film, as well as a better UV protection effect and greater transparency of the coating films. Better morphology and transparency of nanocoating films were achieved by adding TiO2 nanofillers in aqueous dispersion as compared to the addition of TiO2 in powder form. An increase in the glass transition temperature during UV exposure associated with cross-linking in the polymer was less pronounced in the in situ-prepared coating films, confirming better UV protection, while the photocatalytic effect of TiO2 was more pronounced in the ex situ-prepared coating films. The results indicate that the method of preparation has a significant influence on the properties of the coating films.

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Preparation and Properties of Polystyrene/Bacterial Cellulose Nanocomposites by In Situ Polymerization

Journal of Macromolecular Science Part B ◽

10.1080/00222348.2011.556931 ◽

2011 ◽

Vol 50 (10) ◽

pp. 1921-1927 ◽

Cited By ~ 14

Author(s):

Kun Peng ◽

Biao Wang ◽

Shiyan Chen ◽

Chunyan Zhong ◽

Huaping Wang

Keyword(s):

Bacterial Cellulose ◽

In Situ Polymerization ◽

Cellulose Nanocomposites

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Single-walled carbon nanotubes–polyaniline composites: Synthesis and field-emission analysis

Journal of Composite Materials ◽

10.1177/0021998319870571 ◽

2019 ◽

Vol 54 (8) ◽

pp. 1079-1091

Author(s):

Nagma Ansari ◽

Shumaila ◽

Mohd Yaseen Lone ◽

Javid Ali ◽

M Husain ◽

...

Keyword(s):

Electron Microscopy ◽

Field Emission ◽

In Situ Polymerization ◽

Ex Situ ◽

Emission Analysis ◽

Nanocomposite Sample ◽

Single Walled Carbon ◽

Emission Behavior ◽

Polymerization Method

In this article, we report a facile synthesis and comparative analysis of field emission behavior of polyaniline (PANI)-coated as-received and annealed single-walled carbon nanotube (SWCNT) films by in-situ polymerization and ex-situ synthesis routes, respectively. Amongst all the samples, the sample prepared by in-situ polymerization method with more fraction of annealed SWCNTs in the composite gave an enhanced field emission characteristics with E to = 3 V/μm and β = 1.2 × 104 probably because of good formation of pi-pi non-covalent bonds between the SWCNTs and PANI represented by pi-pi interaction between the quinoid rings of PANI and π bond of the SWCNTs lattice. A significant increase in the threshold field is observed after annealing and doping of nanocomposite films. Field emission behavior of as-prepared nanocomposite samples are also analyzed and discussed with two PANI forms: micro-PANI particles and PANI nanofibers. It is also speculated that PANI may have helped in lowering the overall work function of the composite structure which gave an enhanced field emission. The stability of all the samples are also presented and it is analyzed that nanocomposite sample films synthesized by in-situ polymerization method showed a stability for at least 8 h. The surface morphology analysis by field emission scanning electron microscopy of nanocomposite sample films reveal an increase in SWCNTs diameter upon PANI wrapping. The high-resolution transmission electron microscopy and Raman spectra and X-ray diffraction analysis are also presented.

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Antimicrobial bacterial cellulose nanocomposites prepared by in situ polymerization of 2-aminoethyl methacrylate

Carbohydrate Polymers ◽

10.1016/j.carbpol.2015.01.063 ◽

2015 ◽

Vol 123 ◽

pp. 443-453 ◽

Cited By ~ 36

Author(s):

Ana R.P. Figueiredo ◽

Andrea G.P.R. Figueiredo ◽

Nuno H.C.S. Silva ◽

Ana Barros-Timmons ◽

Adelaide Almeida ◽

...

Keyword(s):

Bacterial Cellulose ◽

In Situ Polymerization ◽

Cellulose Nanocomposites

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An in situ and ex situ TEM study of the formation of thin cobalt silicide films by molecular beam epitaxy on the silicon (100) surface

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010010648x ◽

1988 ◽

Vol 46 ◽

pp. 884-885

Author(s):

D. Loretto ◽

J. M. Gibson ◽

S. M. Yalisove ◽

R. T. Tung

Keyword(s):

Molecular Beam Epitaxy ◽

Molecular Beam ◽

Defect Density ◽

High Vacuum ◽

Ultra High Vacuum ◽

Ex Situ ◽

Metal Base ◽

In Situ Experiments ◽

Potential Applications

The cobalt disilicide/silicon system has potential applications as a metal-base and as a permeable-base transistor. Although thin, low defect density, films of CoSi2 on Si(111) have been successfully grown, there are reasons to believe that Si(100)/CoSi2 may be better suited to the transmission of electrons at the silicon/silicide interface than Si(111)/CoSi2. A TEM study of the formation of CoSi2 on Si(100) is therefore being conducted. We have previously reported TEM observations on Si(111)/CoSi2 grown both in situ, in an ultra high vacuum (UHV) TEM and ex situ, in a conventional Molecular Beam Epitaxy system.The procedures used for the MBE growth have been described elsewhere. In situ experiments were performed in a JEOL 200CX electron microscope, extensively modified to give a vacuum of better than 10-9 T in the specimen region and the capacity to do in situ sample heating and deposition. Cobalt was deposited onto clean Si(100) samples by thermal evaporation from cobalt-coated Ta filaments.

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The use of transmission and analytical electron microscopy in studying reactions and phase transformations in thin film

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100150046 ◽

1993 ◽

Vol 51 ◽

pp. 842-843

Author(s):

K. Barmak

Keyword(s):

Thin Film ◽

Thin Films ◽

Phase Transformations ◽

Analytical Electron Microscopy ◽

Ex Situ ◽

Multilayer Thin Films ◽

Absolute Concentration ◽

Analytical Electron ◽

Deposition Step

Generally, processing of thin films involves several annealing steps in addition to the deposition step. During the annealing steps, diffusion, transformations and reactions take place. In this paper, examples of the use of TEM and AEM for ex situ and in situ studies of reactions and phase transformations in thin films will be presented.The ex situ studies were carried out on Nb/Al multilayer thin films annealed to different stages of reaction. Figure 1 shows a multilayer with dNb = 383 and dAl = 117 nm annealed at 750°C for 4 hours. As can be seen in the micrograph, there are four phases, Nb/Nb3-xAl/Nb2-xAl/NbAl3, present in the film at this stage of the reaction. The composition of each of the four regions marked 1-4 was obtained by EDX analysis. The absolute concentration in each region could not be determined due to the lack of thickness and geometry parameters that were required to make the necessary absorption and fluorescence corrections.

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Transmission Electron Microscopy of Epitaxial silicides grown by ultra high vacuum deposition

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100154287 ◽

1989 ◽

Vol 47 ◽

pp. 462-463

Author(s):

D. Loretto ◽

J. M. Gibson ◽

S. M. Yalisove

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Electron Diffraction ◽

High Vacuum ◽

High Energy ◽

Energy Electron ◽

Ultra High Vacuum ◽

Ex Situ ◽

Transmission Electron

The silicides CoSi2 and NiSi2 are both metallic with the fee flourite structure and lattice constants which are close to silicon (1.2% and 0.6% smaller at room temperature respectively) Consequently epitaxial cobalt and nickel disilicide can be grown on silicon. If these layers are formed by ultra high vacuum (UHV) deposition (also known as molecular beam epitaxy or MBE) their thickness can be controlled to within a few monolayers. Such ultrathin metal/silicon systems have many potential applications: for example electronic devices based on ballistic transport. They also provide a model system to study the properties of heterointerfaces. In this work we will discuss results obtained using in situ and ex situ transmission electron microscopy (TEM).In situ TEM is suited to the study of MBE growth for several reasons. It offers high spatial resolution and the ability to penetrate many monolayers of material. This is in contrast to the techniques which are usually employed for in situ measurements in MBE, for example low energy electron diffraction (LEED) and reflection high energy electron diffraction (RHEED), which are both sensitive to only a few monolayers at the surface.

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Atomic Layer Deposition of LiF and Lithium Ion Conducting (AlF3)(LiF)x Alloys Using Trimethylaluminum, Lithium Hexamethyldisilazide and Hydrogen Fluoride

10.26434/chemrxiv.5459653 ◽

2017 ◽

Author(s):

Younghee Lee ◽

Daniela M. Piper ◽

Andrew S. Cavanagh ◽

Matthias J. Young ◽

Se-Hee Lee ◽

...

Keyword(s):

Lithium Ion ◽

Atomic Layer ◽

Mass Gain ◽

Alloy Film ◽

Ex Situ ◽

X Ray ◽

Layer Deposition ◽

Ion Conducting ◽

Good Agreement

<div>Atomic layer deposition (ALD) of LiF and lithium ion conducting (AlF3)(LiF)x alloys was developed using trimethylaluminum, lithium hexamethyldisilazide (LiHMDS) and hydrogen fluoride derived from HF-pyridine solution. ALD of LiF was studied using in situ quartz crystal microbalance (QCM) and in situ quadrupole mass spectrometer (QMS) at reaction temperatures between 125°C and 250°C. A mass gain per cycle of 12 ng/(cm2 cycle) was obtained from QCM measurements at 150°C and decreased at higher temperatures. QMS detected FSi(CH3)3 as a reaction byproduct instead of HMDS at 150°C. LiF ALD showed self-limiting behavior. Ex situ measurements using X-ray reflectivity (XRR) and spectroscopic ellipsometry (SE) showed a growth rate of 0.5-0.6 Å/cycle, in good agreement with the in situ QCM measurements.</div><div>ALD of lithium ion conducting (AlF3)(LiF)x alloys was also demonstrated using in situ QCM and in situ QMS at reaction temperatures at 150°C A mass gain per sequence of 22 ng/(cm2 cycle) was obtained from QCM measurements at 150°C. Ex situ measurements using XRR and SE showed a linear growth rate of 0.9 Å/sequence, in good agreement with the in situ QCM measurements. Stoichiometry between AlF3 and LiF by QCM experiment was calculated to 1:2.8. XPS showed LiF film consist of lithium and fluorine. XPS also showed (AlF3)(LiF)x alloy consists of aluminum, lithium and fluorine. Carbon, oxygen, and nitrogen impurities were both below the detection limit of XPS. Grazing incidence X-ray diffraction (GIXRD) observed that LiF and (AlF3)(LiF)x alloy film have crystalline structures. Inductively coupled plasma mass spectrometry (ICP-MS) and ionic chromatography revealed atomic ratio of Li:F=1:1.1 and Al:Li:F=1:2.7: 5.4 for (AlF3)(LiF)x alloy film. These atomic ratios were consistent with the calculation from QCM experiments. Finally, lithium ion conductivity (AlF3)(LiF)x alloy film was measured as σ = 7.5 × 10-6 S/cm.</div>

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