# Experimental characterization of hydrogel swelling under plant cell wall environment

Carole Antoine Assor, Tancrède Alméras, Françoise Quignard, Olivier Arnould

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Carole Antoine Assor, Tancrède Alméras, Françoise Quignard, Olivier Arnould. Experimental characterization of hydrogel swelling under plant cell wall environment. Plant Biomechanics International Conference PBM8, Nov 2015, Nagoya, Japan., 2015. [hal-01594669](https://hal.science/hal-01594669)

HAL Id: hal-01594669

https://hal.science/hal-01594669

Submitted on 26 Sep 2017

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# Experimental characterization of hydrogel swelling under plant cell wall environment

C. Assorª, T. Almérasᵇ, F. Quignardᶜ, O. Arnouldᵇ

ICG
Montpellier

<figure><img src="image_2.png" /></figure>

UMR iATE
Engineering & emerging technologies

ANR

STRESS
STREETS

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## Context

**Characterization of molecular mechanisms responsible of wood maturation growth stress**

Biomechanic functions of tension wood: weight increase balance and plant orientation control

<figure><img src="image_3.png" /><figcaption>Wood tension</figcaption></figure>

<figure><img src="image_4.png" /></figure>

[B. Clair]

<figure><img src="image_5.png" /><figcaption>Cell wall structure: specific gelatinous G-layer</figcaption></figure>

<figure><img src="image_6.png" /><figcaption>Discrimination of molecular mechanisms producing tissue stress:</figcaption></figure>

## Materiel and methods

<figure><img src="image_7.png" /></figure>

<figure><img src="image_8.png" /></figure>

<figure><img src="image_9.png" /></figure>

-Vertical displacement is locked

-Force due to the “swelling” of the gel is measured continuously

-6 mL of water-dissolved alginates (1, 2 or 3%, dw) are enclosed in a 15 mm diameter dialysis membrane and immersed in 35 mL of 0.1 M $CaCl_2$

-After 24h, hydrogels are cleaned 3x with distilled water and 10 mm disks are sampled from them

<figure><img src="image_10.png" /></figure>

## Results

<figure><img src="image_11.png" /></figure>

<figure><img src="image_12.png" /></figure>

In parallel, free swelling of hydrogels in water is characterised:

-linear correlation between volume and mass variations of samples

$$ \text{swelling} = (\Delta m/m_0) \times 100 $$

Effect of alginate content on hygromechanical properties: free swelling strain and confined swelling stress; elastic shear modulus (rheometer, 0.02-0.1 Hz)

<table><thead><tr><th>Alginate<br>(%, dw)</th><th>ε<sub>max</sub><br>(%)</th><th>σ<sub>max</sub><br>(kPa)</th><th>G'<br>(kPa)</th></tr></thead><tbody><tr><td>1</td><td>129</td><td>0.71</td><td>10</td></tr><tr><td>2</td><td>103</td><td>1.60</td><td>41</td></tr><tr><td>3</td><td>51</td><td>1.75</td><td>86</td></tr></tbody></table>

## Conclusions and perspectives

-The confined swelling stress could more correspond to an osmotic pressure. Additional tests will be established with different alginates structures to characterize the origin of the stress developed.

-The 0.2% deformation of crystalline cellulose estimated within the G-layer require a lateral compressive stress from the matrix closed to 1 MPa, that could not be reached by the osmotic pressure. From these experimental results, it appears that the confined chamber is too stiff as the matrix needs to be less confined to produce a sufficient swelling stress.

-Nano hydrogels could allow to raise a polymer ratio around 20% that would be a more realistic G-layer analog and would allow to study cellulose/matrice interactions.