**6. Applications of HSAG‐SP adducts**

As described in Section 4, HSAG and SP form stable adducts, since the aromatic moiety of the molecule is able to effectively interact with the condensed benzene rings of the graphene lay‐ ers. Moreover, the hydroxy groups brought by SP promote the affinity of the adduct for polar environments. First objective was thus to prepare stable dispersions of HSAG‐SP adducts in polar liquids, such as water.

#### **6.1. Dispersions of HSAG‐SP adducts in water**

Water suspensions were prepared as described in Section 8, with HSAG and HSAG‐SP‐M adducts, with concentrations ranging from 0.1 to 30 g/L. In brief, the solid powder was suspended in water and ball milled (300 rpm, 2 hours). HSAG was observed to settle down, whereas stable suspensions were obtained with the adducts. Vials containing HSAG‐SP water suspensions, with concentrations ranging from 0.10 to 10 g/L, are shown in **Figure 7**.

HSAG‐SP suspensions were observed to follow the Lambert‐Beer law, as it can be seen in the graph in **Figure 8a**. The UV‐Vis spectra in **Figure 8b** confirm the stability of adducts' suspen‐ sions: high absorbance was recorded also upon centrifugation. It has been reported in Section 4.2 that fractionation of HSAG‐SP adducts was obtained only after prolonged centrifugation, at least at 2000 rpm.

Suspensions with high HSAG‐SP concentrations were prepared, up to 200 g/L. Suspensions with 10, 30 and 200 g/L concentrations are shown in **Figure 9**. Stability of the latter suspen‐ sion was obtained by simply adding a small amount (1% w/w) of carboxymethylcellulose. Viscosity was observed to increase slightly, and the suspension was stable for more than a week.

#### **6.2. Antistatic coating layers from HSAG‐SP water suspensions**

Water suspensions of HSAG‐SP adducts are suitable for the preparation of coating layers with antistatic properties. The suspension at 200 g/L was indeed used to prepare coating layers on paper, with the help of a resin to ensure the obtainment of a continuous layer and good grip with the substrate. Ratio between the adduct and the resin ranged from 90/10 to 95/5. As it is shown in **Figure 9d**, the 90/10 layer was characterized by high homogeneity. Resistivity ranged from about 2 to about 4 kOhm/sq.

**Figure 7.** Water suspensions of HSAG (a) and HSAG‐SP (b–h), with the following concentrations (g/L): 10 (b), 5.0 (c), 2.5 (d), 1.0 (e), 0.50 (f), 0.25 (g) and 0.10 (h).

**6. Applications of HSAG‐SP adducts**

190 Graphene Materials - Structure, Properties and Modifications

**6.1. Dispersions of HSAG‐SP adducts in water**

polar liquids, such as water.

comonomer.

at least at 2000 rpm.

a week.

As described in Section 4, HSAG and SP form stable adducts, since the aromatic moiety of the molecule is able to effectively interact with the condensed benzene rings of the graphene lay‐ ers. Moreover, the hydroxy groups brought by SP promote the affinity of the adduct for polar environments. First objective was thus to prepare stable dispersions of HSAG‐SP adducts in

**Figure 6.** HRTEM micrographs of CNT‐PU adduct (a), PE‐CNT adduct (b). PU and PE contain serinol pyrrole as

Water suspensions were prepared as described in Section 8, with HSAG and HSAG‐SP‐M adducts, with concentrations ranging from 0.1 to 30 g/L. In brief, the solid powder was suspended in water and ball milled (300 rpm, 2 hours). HSAG was observed to settle down, whereas stable suspensions were obtained with the adducts. Vials containing HSAG‐SP water

HSAG‐SP suspensions were observed to follow the Lambert‐Beer law, as it can be seen in the graph in **Figure 8a**. The UV‐Vis spectra in **Figure 8b** confirm the stability of adducts' suspen‐ sions: high absorbance was recorded also upon centrifugation. It has been reported in Section 4.2 that fractionation of HSAG‐SP adducts was obtained only after prolonged centrifugation,

Suspensions with high HSAG‐SP concentrations were prepared, up to 200 g/L. Suspensions with 10, 30 and 200 g/L concentrations are shown in **Figure 9**. Stability of the latter suspen‐ sion was obtained by simply adding a small amount (1% w/w) of carboxymethylcellulose. Viscosity was observed to increase slightly, and the suspension was stable for more than

Water suspensions of HSAG‐SP adducts are suitable for the preparation of coating layers with antistatic properties. The suspension at 200 g/L was indeed used to prepare coating layers on

suspensions, with concentrations ranging from 0.10 to 10 g/L, are shown in **Figure 7**.

**6.2. Antistatic coating layers from HSAG‐SP water suspensions**

**Figure 8.** Dependence of UV‐Vis absorbance of HSAG‐SP‐M (1 mg/mL) water suspensions on concentration (g/L) (a) and on storage, sonication and centrifugation (9000 rpm) (b): after sonication (1), after storage at rest for 1 week (2), after centrifugation at 9000 rpm for 10 min (3). UV‐Vis spectrum of HSAG water suspension after centrifugation at 9000 rpm for 10 min as a reference (4).

**Figure 9.** Aqueous suspensions of HSAG‐SP with the following concentrations: (a) 10 g/L, (b) 30 g/L and (c) 200 g/L. Coating layer of HSAG‐SP adduct on paper substrate (see text) (d).

#### **6.3. Nanocomposites with few‐layer graphene in natural rubber as the matrix**

Poly(1,4‐cis‐isoprene) from *hevea brasiliensis* is known as natural rubber (NR) and is the most important rubber, accounting for about 60% of the global rubber market, with a worldwide production of more than 12 million tons per year [91, 92]. It is well known that NR comes from the tree in a latex. The chance of preparing stable water dispersions of HSAG was exploited to obtain homogeneous dispersions of HSAG in NR matrix. Details are in Section 8. Procedure is summarized in **Scheme 4**.

In **Figure 10**, TEM micrograph at high magnification of the nanocomposite formed by NR and HSAG‐SP is shown. Stacks of only a few graphene layers and also isolated graphene layers are visible.

**Scheme 4.** Procedure for the preparation of NR/HSAG‐SP nanocomposite from NR latex.

**Figure 10.** TEM micrograph of NR/HSAG‐SP nanocomposite.

Latex pre‐mixing of nanographite has been indicated [93–95] as the best procedure to obtain highly homogeneous distribution of nanoparticles. Graphene layers are placed around NR globules and form interconnected networks. Low electrical percolation threshold is achieved with low nanographite contents. It is well known that rubber composites are prepared through melt blending that should not only make the latex mixing step redundant, but should also destroy the interconnected network. However, even after melt blending, more homogeneous nanographite dispersion is documented in nanocomposites obtained first via latex blending. In the mentioned references, graphitic layers come from chemically reduced graphite oxide [93], thermally exfoliated graphite oxide [94] and expanded graphite [95] that means from graphites that require relevant treatments.

#### **6.4. Dispersions of HSAG‐SP adducts in polyols**

**6.3. Nanocomposites with few‐layer graphene in natural rubber as the matrix**

**Scheme 4.** Procedure for the preparation of NR/HSAG‐SP nanocomposite from NR latex.

**Figure 10.** TEM micrograph of NR/HSAG‐SP nanocomposite.

is summarized in **Scheme 4**.

192 Graphene Materials - Structure, Properties and Modifications

are visible.

Poly(1,4‐cis‐isoprene) from *hevea brasiliensis* is known as natural rubber (NR) and is the most important rubber, accounting for about 60% of the global rubber market, with a worldwide production of more than 12 million tons per year [91, 92]. It is well known that NR comes from the tree in a latex. The chance of preparing stable water dispersions of HSAG was exploited to obtain homogeneous dispersions of HSAG in NR matrix. Details are in Section 8. Procedure

In **Figure 10**, TEM micrograph at high magnification of the nanocomposite formed by NR and HSAG‐SP is shown. Stacks of only a few graphene layers and also isolated graphene layers

> Dispersions of HSAG‐SP were as well prepared in polyols, as described in Section 8. The goal was to obtain highly homogeneous stable dispersion of graphene layers in a polyol, which means in a precursor of polyurethanes (PUs). PUs are important polymers that account for about 5% of worldwide polymer production and experience an increasing market penetration. Main drawback is their insufficient fire behaviour. Graphite layers are known to impart intu‐ mescent properties to polymer materials. However, due to their poor affinity for the polymeric matrices, they can be hardly dispersed in polyols and have been observed to settle down in short times. In the research reported here, three types of graphites (see **Table 4** in Section 8) were used and stable dispersions were obtained, with concentrations from 2 to 10, as mass%. For example, the suspension with 2% by mass as HSAG‐SP concentration (SP content: 23.5% by mass) was analysed via UV‐Vis spectrophotometry over a month period, observing stable absorption. It is worth commenting that unmodified graphites clearly settled down even after few days. Moreover, the same HSAG‐SP suspension was centrifuged at 3000 rpm for 45 min. The super‐ natant suspension revealed the same UV absorption. In **Figure 11**, 2% by mass suspensions are shown. They were easily prepared (see in Section 8) and are suitable for large‐scale productions.

**Figure 11.** Suspensions in polyol of HSAG Nano 24 (a), flake graphite 3807 (b) and expanded graphite Timrex SFG6 (c).
