Data on synthesis and thermo-mechanical properties of stimuli-responsive rubber materials bearing pendant anthracene groups

The photo-reversible [4πs+4πs] cycloaddition reaction of pendant anthracene moieties represents a convenient strategy to impart wavelength dependent properties into hydrogenated carboxylated nitrile butadiene rubber (HXNBR) networks. The present article provides the 1H NMR data on the reaction kinetics of the side chain functionalization of HXNBR. 2-(Anthracene-9-yl)oxirane with reactive epoxy groups is covalently attached to the polymer side chain of HXNBR via ring opening reaction between the epoxy and the carboxylic groups. Along with the identification, 1H NMR data on the quantification of the attached functional groups are shown in dependence on reaction time and concentration of 2-(anthracene-9-yl)oxirane. Changes in the modification yield are reflected in the mechanical properties and DMA data of photo-responsive elastomers are illustrated in dependence on the number of attached anthracene groups. DMA curves over repeated cycles of UV induced crosslinking (λ>300 nm) and UV induced cleavage (λ=254 nm) are further depicted, demonstrating the photo-reversibility of the thermo-mechanical properties. Interpretation and discussion of the data are provided in “Design and application of photo-reversible elastomer networks by using the [4πs+4πs] cycloaddition reaction of pendant anthracene groups” (Manhart et al., 2016) [1].


a b s t r a c t
The photo-reversible [4πs þ 4πs] cycloaddition reaction of pendant anthracene moieties represents a convenient strategy to impart wavelength dependent properties into hydrogenated carboxylated nitrile butadiene rubber (HXNBR) networks. The present article provides the 1 H NMR data on the reaction kinetics of the side chain functionalization of HXNBR. 2-(Anthracene-9-yl) oxirane with reactive epoxy groups is covalently attached to the polymer side chain of HXNBR via ring opening reaction between the epoxy and the carboxylic groups. Along with the identification, 1 H NMR data on the quantification of the attached functional groups are shown in dependence on reaction time and concentration of 2-(anthracene-9-yl)oxirane. Changes in the modification yield are reflected in the mechanical properties and DMA data of photo-responsive elastomers are illustrated in Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/dib dependence on the number of attached anthracene groups. DMA curves over repeated cycles of UV induced crosslinking (λ 4 300 nm) and UV induced cleavage (λ ¼254 nm) are further depicted, demonstrating the photo-reversibility of the thermomechanical properties. Interpretation and discussion of the data are provided in "Design and application of photo-reversible elastomer networks by using the [4πs þ 4πs] cycloaddition reaction of pendant anthracene groups" (Manhart et al., 2016) [1].
& 2016 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Subject area
Chemistry More specific subject area

Polymer Photochemistry
Type of data CDCl 3 was used as solvent and spectra were referenced to Si(CH 3 ) 4 as internal standard. For DMA measurements, an amplitude of 20 mm and a measurement frequency of 1 Hz were used. The test specimen were heated from À 60°C to þ40°C with a heating rate of 2 K/min.

Experimental features
Functional rubber materials were synthetized and 1 H NMR experiments were performed to verify and quantify the attachment of 2-(anthracene-9-yl)oxirane. Loss factor and storage modulus of photo-reversible rubber materials are provided in dependence on the modification yield and UV exposure dose.

Data source location
Leoben, Austria Data accessibility Data are provided with this article Value of the data 1 H NMR data enables an easy assigning of the proton peaks, which is relevant to determine the modification yield of side chain modified rubber and polymer materials.
Comparison of the reaction kinetics with other epoxy based systems can help to understand the influence of key parameters on the ring-opening reaction between epoxy moieties and carboxylic acid groups.
DMA data allows a deeper understanding of the role of bulky aromatic side chains on the structural-property relationship of elastomer materials.

Data
1 H NMR data on the verification and quantification of HXNBR materials with pendant anthracene groups are provided. DMA data on side chain functionalized HXNBR materials are shown in dependence on the modification yield.

1 H NMR experiments of side chain functionalized HXNBR
The synthesis procedure is provided in Ref. [1]. For the characterization of the reaction kinetics, small amounts of the reaction solution were taken out at selected reaction times of one batch that was stirred at room temperature for 72 h. The reaction solution was immediately precipitated to stop the ongoing reaction and subsequently two purification steps were carried out in which the samples were dissolved in chloroform again and precipitated in cold methanol. After removing the supernatant from the precipitate, the latter was dried at room temperature under vacuum and analyzed regarding its modification yield.
For the quantification of the modification yield, 1 H NMR spectra were referenced to a residual chloroform signal of 7.27 ppm (corresponding to Si(CH 3 ) 4 with a shift of 0.0 ppm) after Fourier transformation. In order to quantify the anthracene signal, the isolated peak at 4.05 ppm was integrated including its complete shoulders on both sides after an appropriate baseline subtraction. For reference purposes, the signal from 2.95 to 0.2 ppm was integrated as it originates from the polymer chain. The modification yield was then calculated according to Eq. (1), wherein the average number of protons per repeating unit was calculated to be 6.033. modification yield ¼ single proton 0 s signal of attached anthracene signal of polymer chain average number of protons per repeating unit ð1Þ Fig. 1 provides the 1 H NMR spectra of HXNBR prior to and after side chain modification with 2-(anthracene-9-yl)oxirane together with the 1 H NMR spectrum of 2-(anthracene-9-yl)oxirane. Fig. 2 shows the reaction kinetics of the side chain modification of HXNBR, which was carried out at room temperature. The number of attached anthracene groups is plotted against the reaction time. The influence of the concentration of 2-(anthracene-9-yl)oxirane in the reaction mixture on the modification yield is displayed.

DMA experiments of side chain functionalized HXNBR
Sample preparation and DMA experiments are detailed in Ref. [1]. Table 1 illustrates the storage modulus at 23°C of side chain modified HXNBR materials in dependence on the modification yield that ranges from 0 to 1.30 mol%. (3) (2) (1)    . DMA curves of rubber-4 upon prolonged UV exposure (λ 4300 nm) over a temperature range from À 60 to þ 40°C. Details of the DMA curves in a narrow temperature range are also given in Ref. [1]. Fig. 5. DMA curves of rubber-4 over repeated cycles of UV induced crosslinking with 46 J/cm 2 (λ 4300 nm, N 2 ) and UV induced cleavage with 9.72 J/cm 2 (λ¼ 254 nm, N 2 ) over a temperature range from À 60 to þ 40°C. Details of the DMA curves in a narrow temperature range are also given in Ref. [1].

Transparency document. Supporting information
Transparency data associated with this article can be found in the online version at http://dx.doi. org/10.1016/j.dib.2016.09.023.