**8. Experimental**

#### **8.1. Materials**

Four grades of graphite have been modified and used in the course of our studies. Their features are summarized in **Table 4**.

Other reagents, described in detail in cited references, were purchased and used without further purifications.

#### **8.2. Synthesis of 2‐(2,5‐dimethyl‐1H‐pyrrol‐1‐yl)‐1,3‐propanediol (serinol pyrrole, SP)**

A mixture of hexan‐2,5‐dione (41.40 g; 0.36 mol) and serinol (30.00 g; 0.33 mol) was poured into a 100 mL round bottomed flask equipped with a magnetic stirrer. The mixture was then stirred, at room temperature, for 6 hours. The yield of the resulting intermediate compound 4a,6a‐dimethyl‐hexahydro‐1,4‐dioxa‐6b‐azacyclopenta[cd]pentalene was estimated to be 99%. Then the mixture was kept under vacuum for 2 hours and subsequently heated to 180°C for 50 min. After distillation under reduced pressure at 130°C and 0.1 mbar, serinol pyrrole (indicated as SP from now on) was isolated as yellow oil with 96% yield [68–70].

#### **8.3. Synthesis of SP on high surface area graphite as the carbon allotrope**

A total of 0.20 g of HSAG, 0.08 g of serinol (0.922 mmol) and 0.11 g of 2,5‐hexanedione (0.922 mmol) were put in a 50 mL round bottom flask, which was also equipped with a magnetic stirrer. The reaction mixture was left to stir at 150°C for 120 min, then it was cooled to room temperature. A sample of black powder was put in a test tube and suspended with deuterated water (D2 O); the so obtained heterogeneous mixture was filtered through a PTFE 0.2 μm filter. The liquid passing through the filter was analysed by Proton Nuclear Magnetic Resonance spectroscopy (1 H‐NMR). NMR spectrum revealed signals that could be attributed only to SP.

#### **8.4. Preparation of HSAG‐SP adducts**

HSAG‐SP adducts were prepared by reacting HSAG and SP with the help of either mechanical (HSAG‐SP‐M) or thermal (HSAG‐SP‐T) energy.

#### *8.4.1. HSAG‐SP‐M adduct*

**7. Conclusions**

194 Graphene Materials - Structure, Properties and Modifications

and of sp2

mechanical or thermal energy.

substrate, more exactly a cycloaddition reaction.

been obtained for graphene layers in natural rubber matrix.

method for obtaining layers of graphene.

features are summarized in **Table 4**.

**8. Experimental**

further purifications.

**8.1. Materials**

Functionalization of graphene layers was performed with a serinol derivative containing a pyrrole ring: 2‐(2,5‐dimethyl‐1H‐pyrrol‐1‐yl)‐1,3‐propanediol, named as serinol pyrrole.

Synthesis of SP was characterized by very high atom economy and yield and thus by a high atom efficiency, close to 90%. A high surface area nanosized graphite was preferentially used as the graphitic substrate, but the reaction with SP was successful with other types of graphite

Reaction was performed by simply mixing SP and the carbon allotrope and giving either

SP and the graphitic substrate revealed strong interaction and formed very stable adducts. Such stability could be explained with the π‐π interaction of the aromatic moieties, the pyrrole ring in SP and the C6 rings in the graphene layers. However, experimental indications seem to support the occurring of a chemical reaction between SP and the aromatic layers of the

By centrifuging water suspensions of HSAG‐SP adducts, stacks of few layers graphene were isolated. The procedure based on the preparation of water suspensions of HSAG‐SP adducts and the subsequent centrifugation appears to be a promising, environmentally friendly

HSAG‐SP adducts allow to envisage a large variety of applications. They form very stable suspensions in water and polyols. Antistatic coating layers have been already prepared and work for the preparation of polyurethanes is in progress. Very homogeneous dispersion has

Four grades of graphite have been modified and used in the course of our studies. Their

Other reagents, described in detail in cited references, were purchased and used without

A mixture of hexan‐2,5‐dione (41.40 g; 0.36 mol) and serinol (30.00 g; 0.33 mol) was poured into a 100 mL round bottomed flask equipped with a magnetic stirrer. The mixture was then stirred, at room temperature, for 6 hours. The yield of the resulting intermediate compound 4a,6a‐dimethyl‐hexahydro‐1,4‐dioxa‐6b‐azacyclopenta[cd]pentalene was estimated to be 99%. Then the mixture was kept under vacuum for 2 hours and subsequently heated to 180°C

**8.2. Synthesis of 2‐(2,5‐dimethyl‐1H‐pyrrol‐1‐yl)‐1,3‐propanediol (serinol pyrrole, SP)**

carbon allotropes, such as carbon black and carbon nanotubes.

HSAG (0.05 g, 66 mmol) and acetone (15 mL) were put in sequence in a 100 mL round bottom flask. The suspension was sonicated for 15 min, using a 2 L ultrasonic bath. After this time, a solution of SP (5.87 g, 66 mmol) in acetone (15 mL) was added and the mixture was sonicated for 15 min. The solvent was then removed under reduced pressure and the graphite/SP black powder was treated using a planetary ball mill whose grinding jar was loaded with six ceramic balls (diameter = 20 mm). After 6 hours of rotation at a rate of 300 rpm, the mixture was thoroughly washed with distilled water (6 × 100 mL) on a funnel with a sintered glass filter and dried in air overnight. A total of 9.80 g of black powder was recovered [70].

#### *8.4.2. HSAG‐SP‐T adduct*

HSAG (5.00 g, 66 mmol), acetone (15 mL) and a solution of SP (1.12 g, 6.6 mmol) in acetone (5 mL) were put in a 100 mL round bottom flask and sonicated as described in Section 8.4.1. Then, after removing the solvent under reduced pressure, the flask was equipped with a magnetic stirrer and the mixture was heated at 130°C for 6 hours under vigorous stirring. After cooling at room temperature, the mixture was repeatedly washed with distilled water (3 × 20 mL) on a funnel with a sintered glass filter and finally dried in air overnight. A total of 5.86 g of black powder was obtained.

#### **8.5. Extraction of HSAG‐SP adducts**

HSAG‐SP adducts were washed using a Soxhlet extractor. In a typical procedure, 3.00 g of black powder was put inside a thimble, which was loaded into the main chamber of the Soxhlet extractor. Acetone was used as the extraction solvent and was placed in a distillation flask. The flask was heated at 70°C, and the extraction was continually performed for 12 hours. After this time, the thimble was removed from the main chamber of the Soxhlet extractor; the powder was recovered and then dried in an oven at 70°C for some hours [70].

#### **8.6. Preparation of water suspensions of HSAG‐SP adducts, evaluation of their stability and microscopic characterization**

Water suspensions of HSAG‐SP adducts at different concentrations (1 mg/mL; 0.5 mg/mL; 0.3 mg/mL; 0.1 mg/mL) were prepared. Each solution was sonicated for 10 min using an ultrasonic bath (260 W) and subsequently UV‐Vis absorption was measured. The solution (10 mL) of each sample was put in a Falcon™ 15 mL conical centrifuge tubes and centrifuged at: 2000 rpm for 10 min and at 9000 rpm for 10, 30, 60 and 90 min. After each centrifugation step, supernatant fluids were picked up, transferred into a cuvette and analysed. UV‐Vis absorptions and DLS analysis were measured immediately after each centrifugation and after 1 week storage.

HRTEM investigations on adducts' samples, isolated from the supernatant solutions after centrifugation, were carried out with a Philips CM 200 field emission gun microscope operating at an accelerating voltage of 200 kV. Few drops of the aqueous solutions were deposited on 200 mesh lacey carbon‐coated copper grid and air‐dried for several hours before analysis. During acquisition of HRTEM images, the samples did not undergo structural transformation. Low‐beam current densities and short acquisition times were adopted. To estimate the number of stacked graphene layers and the dimensions of the stacks visible in HRTEM micrographs, the Gatan Digital Micrograph software was used.

#### **8.7. Preparation of polyol suspensions of HSAG‐SP adducts**

The adducts of SP with Nano 24, 3807 and Timrex SFG6 (SP: graphite = 0.1 molar ratio) were prepared following the procedure described in Section 8.4.2; they were subsequently puri‐ fied by suspending them in acetone (15 mL every gram of adduct), letting the suspension stir overnight and filtering it over a funnel with a sintered glass filter. The powder was subsequently washed several times with acetone until colourless washings and dried in air overnight.

Samples at 2, 5 and 10% (w/w) concentrations of the three SP‐graphite adducts in polyol (Aropol 424™, supplier Pozzi Arosio SAS) were obtained by slowly pouring the chosen grey‐ black dry powder into a vessel containing the viscous liquid while vigorously stirring with a laboratory rod stirrer. After 30 min, the mixture was recovered and stored in PET bottles.

#### **8.8. Preparation of CB‐SP adducts**

Carbon black (1.00 g) and acetone (15 mL) were transferred to a 100 mL round bottom flask and the obtained suspension was sonicated for 15 min, using a 2 L ultrasonic bath. After this time, a solution of SP (0.24 g) in acetone (15 mL) was added. The mixture was sonicated for 15 min. After removing the solvent under reduced pressure, a black powder of SP absorbed carbon black was obtained; 0.70 g of this powder were placed in a vial equipped with a magnetic stirrer. The reaction mixture was heated at 180°C for 2 hours and then let to cool at room temperature; the product was thoroughly washed with distilled water (3 × 100 mL) on a funnel with a sintered glass filter and finally dried in air overnight.

#### **Author details**

After this time, the thimble was removed from the main chamber of the Soxhlet extractor; the

**8.6. Preparation of water suspensions of HSAG‐SP adducts, evaluation of their stability** 

Water suspensions of HSAG‐SP adducts at different concentrations (1 mg/mL; 0.5 mg/mL; 0.3 mg/mL; 0.1 mg/mL) were prepared. Each solution was sonicated for 10 min using an ultrasonic bath (260 W) and subsequently UV‐Vis absorption was measured. The solution (10 mL) of each sample was put in a Falcon™ 15 mL conical centrifuge tubes and centrifuged at: 2000 rpm for 10 min and at 9000 rpm for 10, 30, 60 and 90 min. After each centrifugation step, supernatant fluids were picked up, transferred into a cuvette and analysed. UV‐Vis absorptions and DLS analysis were measured immediately after each centrifugation and after

HRTEM investigations on adducts' samples, isolated from the supernatant solutions after centrifugation, were carried out with a Philips CM 200 field emission gun microscope operating at an accelerating voltage of 200 kV. Few drops of the aqueous solutions were deposited on 200 mesh lacey carbon‐coated copper grid and air‐dried for several hours before analysis. During acquisition of HRTEM images, the samples did not undergo structural transformation. Low‐beam current densities and short acquisition times were adopted. To estimate the number of stacked graphene layers and the dimensions of the stacks visible in

The adducts of SP with Nano 24, 3807 and Timrex SFG6 (SP: graphite = 0.1 molar ratio) were prepared following the procedure described in Section 8.4.2; they were subsequently puri‐ fied by suspending them in acetone (15 mL every gram of adduct), letting the suspension stir overnight and filtering it over a funnel with a sintered glass filter. The powder was subsequently washed several times with acetone until colourless washings and dried in air overnight.

Samples at 2, 5 and 10% (w/w) concentrations of the three SP‐graphite adducts in polyol (Aropol 424™, supplier Pozzi Arosio SAS) were obtained by slowly pouring the chosen grey‐ black dry powder into a vessel containing the viscous liquid while vigorously stirring with a laboratory rod stirrer. After 30 min, the mixture was recovered and stored in PET bottles.

Carbon black (1.00 g) and acetone (15 mL) were transferred to a 100 mL round bottom flask and the obtained suspension was sonicated for 15 min, using a 2 L ultrasonic bath. After this time, a solution of SP (0.24 g) in acetone (15 mL) was added. The mixture was sonicated for 15 min. After removing the solvent under reduced pressure, a black powder of SP absorbed carbon black was obtained; 0.70 g of this powder were placed in a vial equipped with a magnetic stirrer. The reaction mixture was heated at 180°C for 2 hours and then let to cool at

HRTEM micrographs, the Gatan Digital Micrograph software was used.

**8.7. Preparation of polyol suspensions of HSAG‐SP adducts**

powder was recovered and then dried in an oven at 70°C for some hours [70].

**and microscopic characterization**

196 Graphene Materials - Structure, Properties and Modifications

**8.8. Preparation of CB‐SP adducts**

1 week storage.

Maurizio Galimberti\*, Vincenzina Barbera and Annalisa Sironi

\*Address all correspondence to: maurizio.galimberti@polimi.it

Department of Chemistry, Materials and Chemical Engineering "G. Natta", Polytechnic University of Milan, Milan, Italy

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