Characterising the surface adhesive behavior of tablet tooling components by atomic force microscopy

Bunker, Matt; Zhang, Jianxin; Blanchard, Rob; Roberts, Clive J.

doi:10.3109/03639045.2010.546402

Cited by 37 publications

(6 citation statements)

References 54 publications

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“…For example, particle adhesion often dictates the final properties of pharmaceutical products, such as tablets. Moreover, uncontrolled particle adhesion can lead to powder manufacturing problems, resulting in a loss of product. − In addition, minimizing particle adhesion to surfaces is critical in the semiconductor industry, where surface contamination can significantly impact semiconductor production. , Particle adhesion also plays an important role in explosive detection systems, in the design of colloidal dispersions that are stable against aggregation, and in the development of biomimetic polymers. − …”

Section: Introductionmentioning

confidence: 99%

Toward an Improved Method for Determining the Hamaker Constant of Solid Materials Using Atomic Force Microscopy. II. Dynamic Analysis and Preliminary Validation

2021

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The further development of an existing approach-to-contact atomic force microscopy (AFM) method for determining the Hamaker constant, A, of a solid nondeformable material is presented. Upon explicitly accounting for the surface roughness of the given substrate, an estimate of A is directly obtained from the resulting distribution of deflections of the AFM cantilever tip at first contact with the surface, d c. We explore the effects of surface roughness on the resulting d c distributions for several model surfaces. We also analyze the dynamic behavior of the cantilever tip for a range of cantilever approach speeds. At sufficiently slow approach speeds, the dynamic d c distributions are nearly identical to those obtained in the quasi-static limit. Consequently, a method is proposed whereby the relative entropy between the dynamic and quasi-static distributions is used to estimate the value of A. Finally, an experimental test of the method is performed in which the self-Hamaker constant of an amorphous silica surface is determined to be in excellent agreement with the literature established value. Because the surface topography is directly included in the method, the uncertainty in the estimation of the self-Hamaker constant is also significantly reduced, compared to other similar approaches.

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Section: Introductionmentioning

confidence: 99%

Toward an Improved Method for Determining the Hamaker Constant of Solid Materials Using Atomic Force Microscopy. II. Dynamic Analysis and Preliminary Validation

2021

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“…Determining accurate values of A is important for a broad range of scientific and technological applications. For example, understanding and potentially controlling particle adhesion, which is relevant to pharmaceuticals, semiconductors, colloidal dispersions, and explosives detection, − requires accurate estimates of A for various materials.…”

Section: Introductionmentioning

confidence: 99%

Toward an Improved Method for Determining the Hamaker Constant of Solid Materials Using Atomic Force Microscopy. I. Quasi-Static Analysis for Arbitrary Surface Roughness

2020

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The initial development and preliminary validation of improvements to an existing approach-to-contact atomic force microscopy (AFM) method for determining the Hamaker constant, A, of solid materials is presented. The updated method explicitly accounts for the surface topography of the given substrate, which will lead to improved estimates of A and extend the range of the types of the surfaces to which the method can be applied. After deriving a general van der Waals (vdW) force expression between the AFM cantilever tip, treated as an effective sphere, and a surface with arbitrary roughness, the deflection of the cantilever tip at first contact with the surface, d c , is then obtained for all tip locations. Since the vdW force varies locally along the surface, a distribution of d c -values is obtained for a given value of A. For various model surfaces, we discuss the effect of surface roughness on the resulting d cdistributions, which indicates that surface roughness cannot be accounted for in an approximate way. We also present preliminary experimental validation of the updated method, whereby the predicted d c -distribution of a simplified version of an amorphous silica surface is found to compare favorably with the d c -distribution obtained from AFM experiments.

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“…Therefore, sticking is not only drug molecule-specific but is also dependent on drugs’ solid-state properties, including polymorphic form and crystal morphology. − The complexity of tablet adhesion makes the tableting process highly unpredictable and more challenging to identify the root cause of tablet sticking. Different approaches have been adopted to understand or ameliorate the primary mechanism of sticking and picking, including crystal engineering, − atomic force microscopy (AFM), ,, addition of lubricant or coprocessed excipients, , nanocoating to powder, − and different surface modifications to punches using available coating options. − However, all of these approaches are focused on the bulk or particulate level. Sticking and picking issues can be addressed by optimizing formulation components or alteration in the compression tooling.…”

Section: Introductionmentioning

confidence: 99%

Modeling of Adhesion in Tablet Compression at the Molecular Level Using Thermal Analysis and Molecular Simulations

et al. 2021

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The molecular basis of adhesion leading to sticking was investigated by exploring the correlation between thermal analysis and molecular simulations. It is hypothesized that intermolecular interactions between a drug molecule and a punch face are the first step in the adhesion process and the rank order of adhesion during tablet compression should correspond to the rank order of the energies of these interactions. In the present study, the sticking propensity was investigated using ibuprofen, flurbiprofen, and ketoprofen as model substances. At the intermolecular level, a thermal analysis model was proposed as an experimental technique to estimate the work of adhesion between ibuprofen, flurbiprofen, and ketoprofen in a DSC aluminum pan. The linear relationship was established between the enthalpy of vaporization and sample mass to demonstrate the accuracy of the instruments used. The threshold mass for ibuprofen, flurbiprofen, and ketoprofen was determined to be 107, 112, and 222 μg, respectively, after three replicate measurements consistent with the experimental results. Ketoprofen showed a 2-fold higher threshold mass compared to ibuprofen and flurbiprofen, which predicts that ketoprofen should have the highest sticking propensity. Computationally, the rank order of the work of adhesion between ibuprofen, flurbiprofen, and ketoprofen with the metal surface was simulated to be −75.91, 44.75, and −96.91 kcal/mol, respectively, using Materials Studio. The rank order of the interaction between the drug molecule and the iron superlattice decreases in the order ketoprofen > ibuprofen > flurbiprofen. The results indicate that the thermal model can be successfully implemented to assess the sticking propensity of a drug at the molecular level. Also, a new molecular simulation script was successfully applied to determine the interaction energy of the drug molecule upon contact with iron.

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Characterising the surface adhesive behavior of tablet tooling components by atomic force microscopy

Cited by 37 publications

References 54 publications

Toward an Improved Method for Determining the Hamaker Constant of Solid Materials Using Atomic Force Microscopy. II. Dynamic Analysis and Preliminary Validation

Toward an Improved Method for Determining the Hamaker Constant of Solid Materials Using Atomic Force Microscopy. II. Dynamic Analysis and Preliminary Validation

Toward an Improved Method for Determining the Hamaker Constant of Solid Materials Using Atomic Force Microscopy. I. Quasi-Static Analysis for Arbitrary Surface Roughness

Modeling of Adhesion in Tablet Compression at the Molecular Level Using Thermal Analysis and Molecular Simulations

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