Spin coating process of sol-gel silicate films deposition: Effect of spin speed and processing temperature

Воротилов, К. А.; Petrovsky, Vladimir; Vasiljev, V.A.

doi:10.1007/bf00487014

Cited by 51 publications

(24 citation statements)

References 20 publications

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“…The situation is similar to the solvent cast films, and it is most likely the peaks are again caused by the stress in the structure. In this case, the stress is due to the shear stress caused by the centrifugal force during spinning [35]. As the film is annealed, the peaks tend to become less prominent, suggesting the decrease of stress.…”

Section: Conformation and Intermolecular Interactionmentioning

confidence: 99%

“…As discussed previously, the folding surface of the lamellae in solvent cast films should be more uniform, while that in the spin coated films is rougher, which leads to smaller lattice parameters a and b in solvent cast films. Based on the plane spacing equation for orthorhombic cells [22], which is induced by the centrifugal force caused during coating process [35]. Higher annealing temperature gives energy to the molecules to release the stress and to achieve equilibrium state [23]; it also enables molecular chains to change their conformations to that favors chain compacting.…”

Section: Crystal Structurementioning

confidence: 99%

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Effect of Film Formation Method and Annealing on Crystallinity of Poly(L-Lactic Acid) Films

Hsu

Yao

2011

ASME 2011 International Manufacturing Science and Engineering Conference, Volume 1

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Poly(L-lactic acid) (PLLA) has been shown to have potential medical usage such as in drug delivery because it can degrade into bioabsorbable products in physiological environments, and its degradation is affected by crystallinity. In this paper, the effect of film formation method and annealing on the crystallinity of PLLA are investigated. The films are made through solvent casting and spin coating methods, and subsequent annealing is conducted. The resulting crystalline morphology, structure, conformation, and intermolecular interaction are examined using optical microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. It is observed that solvent casting produces category 1 spherulites while annealed spin coated films leads to spherulites of category 2. Distinct lamellar structures and intermolecular interactions in the two kinds of films have been shown. The results enable better understanding of the crystallinity in PLLA, which is essential for its drug delivery application. INTRODUCTIONThere is a significant interest in use of biodegradable polymers due to their biocompatibility and biodegradability. Poly lactic acid (PLA) is a biodegradable polymer and can be obtained from renewable sources such as corn starch. It has a wide range of applications, such as in food packaging and tissue engineering. PLA is also of interest in drug delivery application because it can degrade into bioabsorbable products in physiological environments. Its degradation mainly comes from the cleavage of its ester groups, and is sensitive to chemical hydrolysis. In polymeric drug delivery system, drugs are encapsulated in polymer. As the polymer degrades, the drugs are released, and the release rate is determined by the polymer degradation rate. Crystallinity of polymer is a factor affecting the degradation rate. A good review on the effect of crystallinity on degradation and drug release can be found in [1]. In general, less crystallinity accelerates degradation and drug release rate. To create polymeric drug delivery system, drug molecules are dispersed or dissolved in the polymeric solution, formed through melting the polymer or dissolving it in a solvent. During the process the polymer may crystallize. The crystal structure also influences the degradation rate. Tsuji and Ikada [2] studied the hydrolysis of PLA films and proposed that it begins in the amorphous region between the crystalline lamellae, followed by the disorientation of the lamellae and disappearance of the spherulitic structure.

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Section: Conformation and Intermolecular Interactionmentioning

confidence: 99%

Section: Crystal Structurementioning

confidence: 99%

Effect of Film Formation Method and Annealing on Crystallinity of Poly(L-Lactic Acid) Films

Hsu

Yao

2011

ASME 2011 International Manufacturing Science and Engineering Conference, Volume 1

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“…After annealing, the 1754 cm , which are also located on the right to the gt and tt peaks, respectively; therefore, internal stress could be the reason of the splitting. In addition to solidification, the centrifugal force during the spinning process is another source of the internal stress [48]. However, this stress is only on the order of only several Pa [49], much less than the stress required to split the band and is less likely to be the reason.…”

Section: Conformation Of Molecules and Intermolecular Interactionmentioning

confidence: 99%

Effect of Film Formation Method and Annealing on Morphology and Crystal Structure of Poly(L-Lactic Acid) Films

Hsu

Yao

2014

Journal of Manufacturing Science and Engineering

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The poly(L-lactic acid) (PLLA) has potential medical usage such as drug delivery since it can degrade into bioabsorbable products in physiological environments, while the degradation is affected by its crystallites. In this paper, the effects of film formation method and annealing on the crystallites formed in PLLA films are investigated. The films are made through solvent casting and spin coating, and subsequent annealing is conducted. The resulting morphology, molecular order, conformation, and intermolecular interaction are examined using optical microscopy, wide-angle X-ray diffraction, and Fourier transform infrared spectroscopy. It is observed that solvent casting produces category 1 spherulites while annealing the spin coated films leads to spherulites of category 2. The crystal structure of the two kinds of films also shows distinct features. The results enable better understanding of the crystallites in PLLA, which is essential for its medical application.

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“…Subsequently the second transparent plate with conductive layer was placed on top of the film. Note that the method can leave a thin residual air gap between the film and the top plate, since deposited film inevitably possesses some center-to-edge thickness variation (decrease up to 20%) [11,12]. The gap should be filled to eliminate additional scattering.…”

Section: Introductionmentioning

confidence: 98%

Sol–gel matrix dispersed liquid crystal composite: Influence of methyltriethoxysilane precursor and solvent concentration

Timusk

Järvekülg

Lõhmus

et al. 2010

Materials Science and Engineering: B

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Spin coating process of sol-gel silicate films deposition: Effect of spin speed and processing temperature

Cited by 51 publications

References 20 publications

Effect of Film Formation Method and Annealing on Crystallinity of Poly(L-Lactic Acid) Films

Effect of Film Formation Method and Annealing on Crystallinity of Poly(L-Lactic Acid) Films

Effect of Film Formation Method and Annealing on Morphology and Crystal Structure of Poly(L-Lactic Acid) Films

Sol–gel matrix dispersed liquid crystal composite: Influence of methyltriethoxysilane precursor and solvent concentration

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