Atomic force microscopy and high-resolution scanning electron microscopy study of the banded surface morphology of hydroxypropyl cellulose thin films

Patnaik, Satwik; Bunning, Timothy J.; Adams, W. Wade; Wang, J.; Labes, M. M.

doi:10.1021/ma00105a058

Cited by 36 publications

(15 citation statements)

References 2 publications

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“…We think that this is one of the reasons for inconsistencies in the groove spacing and the band spacing. Using a low-voltage, highresolution scanning microscope and an AFM, Patnaik et al 16 measured the surface morphology of HPC films and observed that the fibrils were sinusoidal about the coating direction with the same wavelength as the shear band: the fibril had an averaged peak-to-valley height of ≈120 nm and an average width of ≈285 nm. In our HPC film, however, such fibrils have not existed.…”

Section: -mentioning

confidence: 99%

Hydroxypropylcellulose Films as Alignment Layers for Liquid Crystals

1999

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Homogeneous surface alignment of liquid crystals (5CB) is observed for films formed by coating with aqueous solutions of hydroxypropylcellulose (HPC) for high coating speeds and thin coating thicknesses. On the other hand, for films formed with isotropic ethanol solutions of HPC, 5CB molecules retain the flow-induced alignment created at the formation of the 5CB droplet. The microstructures responsible for the homogeneous surface alignment are not confirmed in the morphological measurement of the film surface with an atomic force microscope, although large grooves corresponding to the banded texture perpendicular to the coating direction exist on the films formed with liquid crystalline solutions of HPC. The possibility of highly oriented HPC molecules in the coating flow is pointed out using the Doi model. These results suggest that the flow-induced anisotropic orientation of HPC molecules is responsible for the homogeneous surface alignment of 5CB.

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Section: -mentioning

confidence: 99%

Hydroxypropylcellulose Films as Alignment Layers for Liquid Crystals

1999

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“…The HPC film obtained from 60 wt.-% solution at a long shearing time exhibited higher values of orientational order parameter over 0.7 without the banded texture. Patric et al [11] measured the surface morphology of HPC thin films with banded textures using AFM and low-voltage high-resolution scanning microscopy. The fibrils which are made of oriented HPC molecules run sinusoidally about the shearing direction.…”

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confidence: 99%

Cellulose Films as Alignment Layers for Liquid Crystals: Application of Flow-Induced Molecular Orientation

Môri

Morimoto

Nakamura³

1999

Adv. Mater.

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An important feature of liquid crystal displays is surface alignment of the LCs. While mechanical rubbing has been used extensively to induce such alignment, this process also produces dust and static electricity. However, surface alignment in films of hydroxypropylcellulose has recently been achieved in situ during high‐speed thin film production, which utilizes the long relaxation time of flow‐induced orientation (see Figure). Results are summarized in this report.

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“…7a″–c″, the dimensions of aggregates are in the 1.5–2.7 μm range, increasing with concentrations of the casting solution over the 3–5 g/dl domain. Literature shows that, under specific conditions, at higher concentrations, the HPC films morphology gets modified, exhibiting a crystal liquid behavior and/or texture characteristics [23–25].…”

Section: Resultsmentioning

confidence: 99%

Rheological properties and microstructures of cellulose acetate phthalate/hydroxypropyl cellulose blends

Dobos¹,

Onofrei²,

Stoica³

et al. 2012

Polymer Composites

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Cellulose acetate phthalate (CAP)/hydroxypropyl cellulose (HPC) blends were investigated by means of attenuated total reflection‐Fourier transform infrared spectroscopy, thermogravimetry/differential thermal analysis, shear viscosity, oscillatory shear tests, and atomic force microscopy (AFM). Effect of solution concentrations in 2‐methoxyethanol, blend compositions, and shear rate on the rheological functions reflects the mobility of the chain segments or their orientation—with thinning behavior in the shear field. Specific interactions, such as the hydrogen bonds between polymer components and 2‐methoxyethanol used in casting solutions of films, influence the resulting morphology. Supernodular aggregates with different intensities and dimensions, which involve the coexistence of an isotropic and an anisotropic phase, typical for lyotropic cellulosic derivative liquid crystals at low concentrations, are evidenced by AFM images. This study is useful for applications of CAP/HPC blends in pharmaceutical domains.POLYM. COMPOS., 33:2072–2083, 2012. © 2012 Society of Plastics Engineers

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Atomic force microscopy and high-resolution scanning electron microscopy study of the banded surface morphology of hydroxypropyl cellulose thin films

Cited by 36 publications

References 2 publications

Hydroxypropylcellulose Films as Alignment Layers for Liquid Crystals

Hydroxypropylcellulose Films as Alignment Layers for Liquid Crystals

Cellulose Films as Alignment Layers for Liquid Crystals: Application of Flow-Induced Molecular Orientation

Rheological properties and microstructures of cellulose acetate phthalate/hydroxypropyl cellulose blends

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