# Comprehensive SEC and NMR Monitoring of Monomer Functionalization for Dental Composites

Rayenne Latoui, Djallel Bouzid, Manel Taam, Edgar Espinosa-Rodriguez, Olivier Boyron

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Rayenne Latoui, Djallel Bouzid, Manel Taam, Edgar Espinosa-Rodriguez, Olivier Boyron. Comprehensive SEC and NMR Monitoring of Monomer Functionalization for Dental Composites. Macro-molecular Rapid Communications, 2025, 46 (17), pp.2500217. 10.1002/marc.202500217. hal-05448795

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# Comprehensive SEC and NMR monitoring of monomer functionalization for dental composites

Rayenne Latoui<fnref n="1" />, Djallel Bouzid<fnref n="1" />*, Manel Taam<fnref n="2" />, Edgar Espinosa-Rodriguez<fnref n="2" />, Olivier Boyron<fnref n="2" />*

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

## Abstract

Dental materials, particularly composites, require precise monomer functionalization to optimize polymerization and enhance performance. This study investigates the functionalization of triethylene glycol dimethacrylate (TEGDMA) with (3-aminopropyl)triethoxysilane (APTES) via a Michael addition reaction. The primary objective was to monitor functionalization progress and quantify monomer conversion under varying conditions. The focus was on dental composite applications, where controlled functionalization is crucial for optimal polymerization. Additionally, the study aimed to establish a broader range of reaction conditions to achieve variable monomer conversion, beneficial for diverse applications.

The study explored various silane-to-monomer ratios (1:4, 1:2, 1:1, 2:1) and reaction times (2 hours to 7 days) to determine optimal conversion conditions. Two analytical techniques, NMR spectroscopy and size exclusion chromatography (SEC), were used to assess functionalization and conversion. While NMR provided structural confirmation and quantification, SEC proved efficient for both qualitative and quantitative monitoring. It differentiated between single and double functionalization and accurately estimated conversion degrees, providing insights complementary to NMR.

<footnote n="1">¹LGPDDPS, Ecole Nationale Polytechnique de Constantine, 25000 Constantine, Algérie.</footnote>

<footnote n="2">²Univ Lyon, CPE Lyon, CNRS, UMR 5128, CP2M, Equipe PCM, 69100 Villeurbanne, France.</footnote>

<footnote>Email*: [olivier.boyron@univ-lyon1.fr](mailto:olivier.boyron@univ-lyon1.fr)</footnote>
The results demonstrate that SEC is highly effective for tracking the functionalization process, offering reliable data on conversion and reaction kinetics. These findings are essential for tailoring monomer functionalization for applications beyond dental composites.

**Keywords:** TEGDMA, APTES, Functionalization, Michael Addition, NMR, SEC, Dental Composites.
# 1. Introduction

The development of advanced dental composites requires strong cohesion between organic monomers and inorganic fillers.¹⁻⁴ Interfacial interactions between these components play a crucial role in determining the properties of resin-silica hybrids.⁵⁻⁸ Stronger interphase interactions enhance compatibility, leading to superior hybrid material properties.⁶ These interactions can be improved either by modifying the silica surface with functional silanes or by functionalizing the monomers composing the organic resin.⁷ Several studies have explored the use of coupling agents for monomer functionalization to enhance composite performance.⁹⁻¹³

For instance, E. Müh et al. synthesized various alkoxysilyl units via the Michael addition of ethylene glycol acrylate methacrylate (EGAMA) and ethylene glycol bisacrylate (EGBA) to different R,ω-alkoxysilylamines.¹¹ These hybrid monomer mixtures were then combined with Bis-GMA and silica particles to obtain composites with a filler content of 70 wt.%. In a parallel study, N. Moszner et al. developed novel methacryloyloxyalkylaminoalkylalkoxysilanes through the Michael addition of corresponding acryloyloxyalkyl methacrylates with APTES.¹⁰ Their findings highlighted that, in addition to improving compatibility, the formation of high-molecular-weight hybrid monomers significantly reduces volumetric shrinkage in composites.

The Michael addition is a nucleophilic conjugate addition reaction that enables the modification of electron-deficient olefins, such as methacrylate groups, through the addition of nucleophiles like thiols or amines.¹⁴⁻¹⁶ This reaction is particularly advantageous for the synthesis of novel polymer precursors, as it proceeds under mild conditions, offers high selectivity, and allows precise control over the chemical structure of the resulting monomers.¹⁷,¹⁸

The goal of this study was to monitor the reaction progress and determine optimal conditions for the functionalization of TEGDMA with APTES. While our primary focus was the formulation of dental composites, where controlled monomer conversion is crucial for maintaining polymerization potential, we also aimed to establish a broader range of reaction conditions. This would provide adaptable conversion values for other applications that require either high or low functionalization.
To assess the efficiency of the functionalization, two complementary analytical techniques, NMR spectroscopy and size-exclusion chromatography (SEC), were used. While NMR provided structural confirmation and quantitative analysis of monomer conversion, SEC offered additional insights by distinguishing different functionalization types (single or double) through molar mass comparisons with theoretical values. Furthermore, SEC enabled the detection of by-products, which was not possible with NMR alone, making it an essential tool for a comprehensive assessment of the functionalization reaction. Few studies have used SEC as a qualitative approach for tracking monomer functionalization in combination with other techniques¹⁷⁻¹⁹, and our original study exploited it effectively as both a qualitative and quantitative method.

## 2. Materials and methods

### 2.1 Materials

The monomer used in this study was triethylene glycol dimethacrylate (TEGDMA) (95% purity, containing 80–120 ppm MEHQ inhibitor), purchased from Sigma-Aldrich, Spain. The silane coupling agent employed for functionalization was (3-aminopropyl) triethoxysilane (APTES), also obtained from Sigma-Aldrich, Spain. For size-exclusion chromatography (SEC) analysis, tetrahydrofuran (THF) was used as the mobile phase solvent, while deuterated chloroform (CDCl₃) served as the solvent for NMR spectroscopy. Both solvents were supplied by Sigma-Aldrich.

### 2.2 Functionalization reaction

The synthesis of the hybrid monomer TEGDMA-APTES was achieved via Michael addition (1, 4) reaction as shown in Figure 1. TEGDMA and APTES were mixed in different molar ratios (1:4, 1:2, 1:1, and 2:1). Mixing was performed with a magnetic stirring at room temperature. Reaction times ranged from 2h to 7 days, with periodic sampling for analysis.
<figure><img src="image_3.png" /><figcaption>**Figure 1:** APTES-mediated functionalization of TEGDMA via Michael addition (1,4).</figcaption></figure>

## 2.3 Size exclusion chromatography

Size exclusion chromatography (SEC) analyses were performed using a 1260 Infinity II LC system from Agilent Technologies, equipped with a refractive index (RI) detector, a UV detector, a viscometer and a multi-angle light scattering detector. The separation was achieved with two Mixed-D columns (Agilent, 5 µm, 300 x 7.8 mm) thermostated at 35°C to maintain consistent temperature conditions. Tetrahydrofuran (THF) was selected as the mobile phase at a flow rate of 1 mL/min. GPC/SEC Software (Agilent) was used for data acquisition, processing, and subsequent calculation of molar masses. A conventional calibration curve was constructed using narrow polystyrene standards from Agilent (range: 160 – 10,000 g mol⁻¹) to determine the average molar masses (Mn, Mw). SEC was used to monitor the functionalization of TEGDMA both qualitatively and quantitatively, providing insights into molar mass distribution, the degree of functionalization (single or double), and the presence of by-products.

## 2.4 Nuclear Magnetic Resonance (NMR)

¹H NMR spectra of liquid solutions of functionalized monomer were recorded in deuterated chloroform (CDCl₃) at concentrations of 250 g/L on a BRUKER AVANCE 300 spectrometer (7.05 T). A broadband BBO multinuclear probe (5 mm BB/19F-1H/D Z-<GRD) was used with the "zg30" pulse sequence to optimize signal acquisition. A total of 512 acquisitions were collected with a 4µs pulse duration (90° filp angle) and a recycling delay of 2s to ensure complete relaxation. The chemical shift reference for ¹H NMR experiments was tetramethylsilane (TMS; d = 0 ppm). Spectra were processed by Bruker Topspin 3.6.5 software, with chemical shifts
reported in ppm. The integration of key proton signals was used to assess the degree of
functionalization, and quantify the conversion yield of the reaction.

**3. Results and discussion**

**3.1 Synthesis of functionalized TEGDMA-APTES hybrid monomer**

The functionalization of TEGDMA via the Michael addition reaction proceeds through a nucleophilic attack mechanism. The amine group of APTES, with its non-bonding electron pair, attacks the methacrylate double bond between the α and β carbons of TEGDMA (Figure 1). This leads to the formation of an enolate intermediate, which then acts as a nucleophile, attacking the β carbon of the α, β-unsaturated monomer. The reaction occurs at the carbonyl group of the methacrylate (carbon β), forming a bond between carbon β and the amine nitrogen, resulting in the depletion of vinyl groups.

This reaction leads to the formation of the Michael adduct comprising the bond between the
monomer and APTES. The obtained functional monomers were characterized using SEC
analysis as well as ¹H NMR spectroscopy.

**3.2 Monitoring TEGDMA Functionalization by SEC**

Figure 2 shows SEC curves of pure TEGDMA and pure APTES.

<figure><img src="image_4.png" /><figcaption>**Figure 2:** SEC chromatograms of pure TEGDMA and APTES.</figcaption></figure>
The molar masses of TEGDMA and APTES, 280 g mol⁻¹ and 228 g mol⁻¹ respectively, calculated by SEC, are very close to the theoretical molar masses, 286 g mol⁻¹ and 221 g mol⁻¹ respectively. This agreement suggests that SEC, equipped with columns suitable for small molar masses, can effectively detect changes in molar mass associated with the modification of TEGDMA by APTES. It is a reliable method for providing accurate data to support the reaction progress and the formation of functionalized products.

As observed in Figure 2, at the same concentration, the APTES signal is weak. This is confirmed by dn/dc values measured with the refractometer, revealing an extremely low dn/dc of 0.001 mL/g for APTES, 36 times lower than TEGDMA (0.036 mL/g). Consequently, the SEC peak intensity of APTES is significantly reduced (Figure 2), making its signal negligible compared to TEGDMA and challenging to detect and quantify in its presence.

The functionalization reaction of TEGDMA using different molar ratio of TEGDMA to APTES for different time was carried out by SEC (Figure 3).

<figure><img src="image_5.png" /><figcaption>**Figure 3:** SEC monitoring of the functionalization reaction: peak evolution over time at various silane to TEGDMA ratios 1:4 (a), 1:2 (b), 1:1 (c), and 2:1 (d).</figcaption></figure>
The analysis revealed the appearance of a high molar mass peak between 500 and 600 g mol⁻¹ corresponding to the functionalized monomer (Peak 2). This peak represents the monomer that has undergone successful single functionalization. It aligns well with the theoretical molar mass of a TEGDMA molecule reacted with one APTES molecule, confirming the expected reaction product.

Peak 1, which represents the superposition of the two residual components (TEGDMA and APTES) due to their nearly identical molar masses, is primarily attributed to unreacted TEGDMA, as the APTES signal is negligible. A shoulder peak (S3) appears at higher silane amount, indicating double functionalization of TEGDMA. The increase in molar mass associated with this shoulder supports the hypothesis that the excess silane favors dual functionalization, leading in the attachment of two APTES molecules per TEGDMA monomer. This is the most likely explanation, as it aligns with the expected reaction mechanism under these conditions and provides further insight into the impact of reactant ratios on product distribution. While this peak could also indicate the formation of oligomers, arising from APTES self-condensation through its silanol groups, the double functionalization mechanism appears to be the primary process in this case.

A consistent low molar mass peak at 90 g/mol is observed in the SEC analysis, attributed to a residual peroxide from THF degradation. This peak appears in all experiments with constant intensity, including in the pure products (Figure 2), indicating that it originates from the solvent rather than the sample itself. Its identity was confirmed using GC-MS analysis.

Figure 4 shows the evolution of mass fraction for reaction products at various silane to TEGDMA ratios 1:4 (a), 1:2 (b), 1:1 (c), and 2:1 (d). The mass fraction is calculated by integrating the area under each peak to determine the relative contribution of each component, according to the formula:

$$f_i = \frac{A_i}{\sum A_i} \qquad (1)$$

where $f_i$ is the mass fraction of component i, $A_i$ is the area of peak i, and $\sum A_i$ is the total area of all the peaks.
<figure><img src="image_6.png" /><figcaption>**Figure 4:** Time-dependence of the mass fractions of TEGDMA and TEGDMA functionalized at various silane to TEGDMA ratios 1:4 (a), 1:2 (b), 1:1 (c), and 2:1 (d).</figcaption></figure>

As expected, no reaction was observed with small quantities of APTES, in less than 8h while addition of a quantity equivalent to the amount of TEGDMA of APTES led to 24% TEGDMA conversion in 24h.

This can be explained by the increase in interactions between the two reactants. With a higher silane concentration, the probability of silane molecules encountering monomer molecules within a given time period increases considerably. This leads to an increase in reaction frequency and the formation of a greater number of functionalized monomers.

Despite the appearance of a shoulder in the SEC trace suggesting double functionalization for a 2:1 ratio, the overall conversion of TEGDMA did not exceed 56% (Figure 4-d). This limited conversion can be explained by diffusion problems, as the reaction progresses. The increasing viscosity of the reaction medium, along with the steric hindrance caused by the growing size of the functionalized monomers, may restrict the accessibility of the TEGDMA reactive sites to the APTES molecules. Additionally, the lower reactivity of methacrylates with amines further contributes to the incomplete conversion. An analysis by Konuray et al. of aza-Michael
reaction kinetics of a system containing both acrylates and methacrylates with an amine found
that acrylate-rich mixtures achieved a higher overall conversion than methacrylate-rich
mixtures. However, the latter exhibited the highest crosslinking density and thermal
resistance.²⁰ Figure 5 shows the effect of molar ratio on the functionalization reaction.

<figure><img src="image_7.png" /><figcaption>**Figure 5:** Evolution of peaks (a) and mass fraction (b) with APTES to TEGDMA ratio after 48h reaction.</figcaption></figure>

The increase in APTES content had a noticeable impact on monomer conversion, as shown in
Figure 5. For the reaction at 48 hours, a two-fold increase in APTES concentration led to a
proportional rise in monomer conversion, increasing from 24% to 45%.

While SEC provides valuable information about the molar masses of the products present in
the reaction medium and can suggest the formation of functionalized monomers, it is unable
to confirm the precise chemical structure of the species involved. ¹H NMR, on the other hand,
can directly identify functional groups of the species by their characteristic proton signals,
providing more precise evidence of the occurrence and evolution of the reaction.

3.3 Monitoring TEGDMA Functionalization by ¹H NMR

The NMR spectra for pure TEGDMA, pure APTES, and the reaction mixture at 48 hours were
recorded in Figure 6.
<figure><img src="image_8.png" /><figcaption>**Figure 6:** ¹H NMR spectra of pure APTES and TEGDMA before and after reaction (48 hours).</figcaption></figure>

The characteristic peaks corresponding to the methacrylate groups (–CH₂=C(CH₃)COO–), the amine group (–NH₂), and the ethoxy groups (–Si(OEt)₃) are observed at respectively 5.5 ppm and 6.1 ppm, 1.2 ppm, and 3.8 ppm. The detailed assignments are provided in the figure. In the reaction mixture, the spectrum exhibits characteristic signals of both TEGDMA and APTES, confirming their presence in the reaction medium.

Methacrylate chain-end transformations are effectively observed through ¹H NMR spectra, as represented in Figure 7.
<figure><img src="image_9.png" /><figcaption>**Figure 7:** ¹H NMR spectra depicting chain end transformation during the addition of APTES to TEGDMA with APTES: TEGDMA molar ratio equal to 1:1 at different time.</figcaption></figure>

The consumption of the methacrylate double bond (C=C) is evidenced by the progressive decrease of the characteristic signals of the vinylic protons at 5.5 and 6.1 ppm over time. The intensities of these peaks decrease from 1.8 at 24 hours to 1.3 at 7 days, as shown in Figure 7. This change confirms the occurrence of the functionalization reaction.

The conversion of TEGDMA to the functionalized monomer shown in Table 1 was calculated by following the decrease in the area of the signal corresponding to the two characteristic protons of the methacrylate double bond (C=C) visible in the NMR spectrum around δ ≈ 5.5 and δ ≈ 6.1 ppm as shown in Figure 6 and 7 (formula 2). To ensure accuracy, an internal reference signal (d+d'), corresponding to protons from CH₂ group of the alkyl chain of the TEGDMA molecule unaffected by the reaction, was chosen. This reference was chosen for its stability, cleanliness and isolation from the double bond region in the NMR spectrum, ensuring accurate integration and reliable quantification. The observed NMR results indicate a successful Michael addition reaction between APTES silane and TEGDMA monomer.

The general formula for conversion is:

$$ \text{Conversion (\%)} = \frac{I_{\text{initial}} - I_{\text{final}}}{I_{\text{initial}}} \times 100 \qquad (2) $$
where:

* $I_{initial}$ is the integration of the vinylic-methacrylate peaks before the reaction (in pure TEGDMA), $I_{initial}=2$ (not shown in Figure 7).

* $I_{final}$ is the integration of the vinylic-methacrylate peaks after the reaction.

### 3.4 Comparative study

Table 1 shows the conversion values calculated through SEC and NMR analysis enabling a direct comparison between the results founded by the two techniques.

Since the initial reaction mixture contains TEGDMA and APTES, but the signal of APTES is negligible, we can assume that the mass fraction at the start is primarily TEGDMA, and it is close to 1 (i.e., $w_0 \approx 1$). This simplifies the conversion formula:

$$ \text{Conversion (\%)} = \frac{w_0 - w_f}{w_0} \times 100 \quad (3) $$

Where

* $W_f$ is mass fraction of the unreacted TEGDMA monomer determined by SEC analysis.

* $W_0$ is the initial mass fraction of TEGDMA, approximately 1 at the start of the reaction.

<table><caption>**Table 1:** Monomer conversion (%) as a function of reaction time and silane ratio.</caption><thead><tr><th rowspan="3">APTES :<br>TEGDMA</th><th colspan="8">Methacrylate conversion<sup>a)</sup> (%)</th></tr><tr><th colspan="2">24 h</th><th colspan="2">48 h</th><th colspan="2">72 h</th><th colspan="2">7 days</th></tr><tr><th>NMR</th><th>SEC</th><th>NMR</th><th>SEC</th><th>NMR</th><th>SEC</th><th>NMR</th><th>SEC</th></tr></thead><tbody><tr><td><b>1:4</b></td><td>2.5</td><td>3.1</td><td>5.5</td><td>6.2</td><td>8.0</td><td>7.8</td><td>11.5</td><td>11.5</td></tr><tr><td><b>1:2</b></td><td>7.5</td><td>6.1</td><td>12</td><td>13.3</td><td>15.5</td><td>15.8</td><td>24.5</td><td>24.1</td></tr><tr><td><b>1:1</b></td><td>10.5</td><td>15.2</td><td>20.5</td><td>27.6</td><td>23.5</td><td>30.7</td><td>35.5</td><td>41.6</td></tr><tr><td><b>2:1</b></td><td>19.0</td><td>22.9</td><td>31.5</td><td>41.0</td><td>42.0</td><td>45.6</td><td>60.0</td><td>55.6</td></tr></tbody></table>

Similar trends to those observed by SEC analysis were observed in the ¹H NMR spectra which confirmed the efficiency of SEC analysis to monitor the reaction as simple technique.
For dental applications, a full conversion of TEGDMA is not necessary, as residual double bonds are required for copolymerization with Bis-GMA in the subsequent formulation step. At a 1:1 ratio and 48h reaction time, a balance between functionalization and copolymerization capability was achieved. Excessive silane led to undesired side reactions (hydrolysis) and multiple functionalization events.

However, beyond this specific application, we also aimed to establish a broader range of reaction conditions to achieve variable monomer conversion, which may be beneficial for other applications requiring different levels of functionalization.

### 4. Kinetic study of TEGDMA functionalization via Michael addition

To evaluate the kinetics of TEGDMA functionalization with APTES via Michael addition, the monomer conversion was monitored over time using SEC analysis. Reactions were carried out at varying APTES: TEGDMA molar ratios (1:4, 1:2, 1:1, and 2:1) with reaction times ranging from 24 hours to 7 days.

The conversion of TEGDMA into its functionalized form was calculated based on the mass fraction obtained from SEC analysis (Equation 1). Due to the negligible signal of APTES relative to TEGDMA, the functionalization progress was mainly assessed through the decrease in TEGDMA concentration over time.

To model the kinetics of the functionalization process, we applied a first-order kinetic law with exponential decay. This model assumes that the rate of the reaction depends on the concentration of the reactant, leading to an exponential decrease as the reaction progresses. The conversion $X(t)$ of TEGDMA over time was fitted using the following exponential decay model:

$$X(t) = X_{\max} \times (1 - e^{-kt}) \quad (4)$$

where:

* $X_{\max}$ is the maximum theoretical conversion observed for each molar ratio,

* k is the reaction rate constant,

* t is the reaction time (in hours).

All fitting parameters are summarized in Table 2.
<table><caption>**Table 2:** Fitting parameters for each molar ratio.</caption><thead><tr><td>Ratio</td><td>Equation</td><td>X<sub>max</sub></td><td>k</td><td>R<sup>2</sup></td></tr></thead><tbody><tr><td>1:4</td><td>X(t)=13(1-e<sup>-0.012t</sup>)</td><td>13.0</td><td>0.012</td><td>0.998</td></tr><tr><td>1:2</td><td>X(t)=27.6(1-e<sup>-0.021t</sup>)</td><td>27.6</td><td>0.013</td><td>0.992</td></tr><tr><td>1:1</td><td>X(t)=43.2(1-e<sup>-0.018t</sup>)</td><td>43.2</td><td>0.018</td><td>0.986</td></tr><tr><td>2:1</td><td>X(t)=57(1-e<sup>-0.023t</sup>)</td><td>57.0</td><td>0.023</td><td>0.981</td></tr></tbody></table>

Using the fitted equations, an abacus was constructed by plotting conversion X(t) as a function of reaction time for each molar ratio. The abacus allows for the estimation of monomer conversion at any given reaction time and for different reactant proportions.

The obtained equations for each molar ratio are plotted in Figure 8.

<figure><img src="image_10.png" /><figcaption>**Figure 8:** Time-dependent conversion of TEGDMA at different APTES:TEGDMA ratios with exponential fit.</figcaption></figure>

The plotted curves show that higher APTES:TEGDMA ratios lead to higher maximum conversions, indicating an increased efficiency of functionalization. The reaction rate constant k increases with APTES content, suggesting a catalytic or reactivity-enhancing effect of APTES on the Michael addition reaction.
The observed trend aligns with the expected behavior of Michael addition reactions, where excess nucleophile (APTES) facilitates the reaction by providing more active amine sites. This effect is particularly evident at a 2:1 molar ratio, where the conversion reaches 55.6% after 7 days.

These findings highlight the influence of reactant ratio and reaction time on the functionalization efficiency, providing essential guidance for optimizing synthesis conditions in future studies.

For the formulation of dental composites, a molar ratio of 1:1 and a reaction time of 48 hours were selected as the optimal conditions, yielding a monomer conversion of 28%, which is sufficient to retain unreacted double bonds necessary for subsequent copolymerization with Bis-GMA. Excessive silane functionalization is unnecessary, as maintaining a lower degree of modification preserves these reactive sites. The functionalized monomer is then combined with tetraethyl orthosilicate (TEOS) to generate silica through hydrolysis and condensation, enhancing cohesion in the composite before final photopolymerization, as shown in Figure 9.²¹ This controlled approach ensures a balance between reactivity and material integrity, contributing to the overall performance of the dental composite.

<figure><img src="image_11.png" /><figcaption>**Figure 9:** Schema of the formation mechanism of the silica nanoparticles in the methacrylic resin.</figcaption></figure>

## 5. Conclusion

This study successfully demonstrated the functionalization of TEGDMA with APTES via a Michael addition reaction, confirming the reaction's occurrence and quantifying monomer conversion under varying conditions. Both SEC and NMR analyses confirmed the formation of
functionalized monomers, providing key insights into the reaction mechanism and product distribution. In addition to yielding conversion values comparable to those obtained by NMR, SEC proved to be particularly useful for distinguishing between single and double functionalization, as well as for detecting reaction by-products. These aspects are critical for optimizing the functionalization process and ensuring the purity of the final product, particularly in applications where well-defined chemical structures are required.

Despite its advantages, SEC remains underutilized in the field as a dual qualitative and quantitative technique for tracking monomer functionalization. This study highlights its potential to complement traditional analytical methods, offering a more comprehensive characterization of functionalized monomers.

In the context of dental composites, the optimal 1:1 silane-to-monomer ratio ensures sufficient functionalization while preserving essential methacrylate double bonds for subsequent copolymerization. However, by exploring different reaction parameters, we established a broader conversion range that could be tailored to other applications where variable monomer functionalization is required. This flexibility makes the developed approach applicable not only to dental materials but also to other polymer systems that benefit from controlled silane modifications.

Future work could focus on refining reaction conditions to further optimize the functionalization efficiency and evaluating the impact of the functionalized monomer on the final composite properties. Additionally, exploring alternative nucleophiles or reaction pathways could extend the applicability of this functionalization strategy to a wider range of polymeric materials.

**Acknowledgments:**

The authors thank David Gajan from the NMR polymer center for assistance and access to the NMR facilities. We also thank Adam Eris and Thierry Desperonnat from Agilent Technologies for their support in size exclusion chromatography.
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