# Strengthening Polylactic Acid by Salification: Surface Characterization Study

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## Abstract

**:**

## 1. Introduction

#### 1.1. Atomic Force Microscopy Techniques

#### 1.2. 3D-Printed Artificial Heart Valves

#### 1.3. Motivation and Objectives

## 2. Methods and Materials

_{ts}) and dissipated power (P

_{ts}), which are convolutions of the tip–sample interactions with position and velocity, respectively. Equations (1) and (2) describe the conversions, where index i specifies the corresponding eigenmode under study, $k$ is the stiffness, $A$ the instantaneous amplitude, ${A}_{0}$ the free amplitude, $f\_exc$ the excitation frequency, ${f}_{0}$ the free resonance frequency, $\varphi $ the phase, and $Q$ the quality factor. Based on these equations, if the imaging mode is simple tapping mode where the excitation frequency is equal to the resonance frequency, the ${f}_{exc}/f$ will be reduced to one and will simplify the equations [19,20].

## 3. Results and Analysis

## 4. Conclusions

## Author Contributions

## Funding

## Institutional Review Board Statement

## Data Availability Statement

## Conflicts of Interest

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**Figure 2.**Tapping mode AFM results:

**Top Row**: topography images for samples 1, 2, and 3 from left to right.

**Bottom Row**: Phase images for samples 1, 2, and 3 from left to right. Scan sizes are $5\mathsf{\mu}\mathrm{m}\times 5\mathsf{\mu}\mathrm{m}$ with a scan rate of 1 Hz, free oscillation amplitude of 100 nm, with 60% setpoint.

**Figure 3.**Results for virial and dissipated power for three PLA samples of increasing salt concentrations.

**Figure 4.**Topography, phase 1, and phase 2 results for bimodal imaging of three PLA samples of increasing salt concentration.

**Figure 5.**Force spectroscopy results: (

**a**) three-dimensional topography of three PLA samples overlayed with a color scale representing the phases; (

**b**) two force curves of sample 2 on an area of high salt concentration vs. a primarily PLA area; (

**c**) effective Young’s modulus results using force spectroscopy and the DMT contact model; (

**d**) spring and AFM tip representation of the DMT contact model.

Sample Number | % Weight NaCl Concentration |
---|---|

1 | 10 |

2 | 15 |

3 | 20 |

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**MDPI and ACS Style**

Schlosser, J.; Keller, M.; Fouladi, K.; Eslami, B.
Strengthening Polylactic Acid by Salification: Surface Characterization Study. *Polymers* **2023**, *15*, 492.
https://doi.org/10.3390/polym15030492

**AMA Style**

Schlosser J, Keller M, Fouladi K, Eslami B.
Strengthening Polylactic Acid by Salification: Surface Characterization Study. *Polymers*. 2023; 15(3):492.
https://doi.org/10.3390/polym15030492

**Chicago/Turabian Style**

Schlosser, Jessica, Michael Keller, Kamran Fouladi, and Babak Eslami.
2023. "Strengthening Polylactic Acid by Salification: Surface Characterization Study" *Polymers* 15, no. 3: 492.
https://doi.org/10.3390/polym15030492