# Synthesis and Porous Structure Characteristics of Allyl Methacrylate/Divinylbenzene Polymers
## 3 Results and Discussion  
### FTIR and Raman Spectroscopy Results  
The aim of the present work is to obtain relatively polar polymers of allyl methacrylate (AllMeth) and divinylbenzene (DVB) and to investigate their porous structure characteristics. After the polymerization of all polymers under the conditions described in the Experimental section, they were analyzed using both FTIR and Raman spectroscopy in order to confirm the incorporation of both monomers into the polymeric network. The presence of allyl groups was of particular interest.  
In Figure 1, the exemplary FTIR spectrum is shown. It confirms the presence of ester bonds with a sharp and strong peak at 1724 cm\({}^{-1}\) ascribed to the stretching of the C=O bond. In the fingerprint region, the proof of the existence of the m- and p-substituted phenyl ring from the DVB crosslinker is seen. Stretching of the v (H-C=C) bond is shown as a medium strength peak at 2932 cm\({}^{-1}\). Stretching of v (C=CH\({}_{2}\)) is giving a weak peak at 1648 cm\({}^{-1}\).  
Raman spectrum was recorded for the same purpose as FTIR, which is to confirm the presence of allyl bonds in the crosslinked polymers.  
In Figure 2, the exemplary Raman spectrum is presented. As can be seen, the allyl bond is also present, which gives the information that at least part of the allyl bonds is still present in the copolymer. The same stretching of v (H-C=C) is ascribed to a strong peak at 2923 cm\({}^{-1}\). Stretching of v (C=CH\({}_{2}\)) is giving Raman spectra a strong peak at 1632 cm\({}^{-1}\)  
Figure 1: The FTIR spectrum of AllMeth/DVB resin.  
The proportion between the amount of allyl bonds, which should be theoretically present, and the actual amount cannot be calculated from the spectra as it only has a qualitative character. At that moment, it was not possible to judge if some allyl bonds were taking part in crosslinking and to what extent. It should be mentioned that in radical polymerization, the reactivity of the allyl bond is 100 times lower than the reactivity of the vinyl bonds, both in methacrylate and divinylbenzene.  
However, in the literature, it can be found that the use of the allyl methacrylate as a crosslinker in making monodispersed poly(methyl methacrylate) particles led to a polymeric system in which it was possible to detect a glass transition temperature at 142.7 \({}^{\circ}\)C. This temperature was ascribed to the formation of linear poly(allyl methacrylate) sequences, linking seeded poly(methyl methacrylate) but using the vinyl groups only and not the allyl groups [27]. That conclusion was supported by the results published in [28], in which the poor polymerizability of allyl groups was explained by a readily acruing chain transfer. So, the conclusion was that allyl groups remained as the free groups that were not involved in cross-linking. The same conclusion was reached in [29], where a copolymer of methyl methacrylate and allyl methacrylate was used as core material in the formation of core/shell particles. The authors claimed that the free (unreacted) allyl groups were serving as anchors to attach shell copolymer and prevent mechanical decomposition. Unreacted in radical polymerization, in this case, iCVD (initiated Chemical Vapour Deposition), allyl groups were subsequently used in UV cross-linking [30]. In another paper [31], allyl methacrylate was used as a dual crosslinker in the synthesis of a semi-IPN hydrogel. The nominal amount of crosslinker was 5 wt%. Taking all of the above and the results of FTIR and Raman spectroscopy in this work, it can be stated that at least part of the allyl groups are still present in the crosslinked polymers that were obtained.