Manufacturing and photocrosslinking of a new bio‐based dimethacrylate resulting in hydrophobic crosslinked films

Abstract

A new bio‐based dimethacrylate (EMHO) consisting of three isomers, that is (ethane‐1,2‐diyl‐bis(9‐methacryloyloxy‐10‐hydroxy octadecanoate) [EMHO‐i1], ethane‐1,2‐diyl‐9‐hydroxy‐10‐methacryloyloxy‐9′‐methacryloyloxy‐10′‐hydroxy octadecanoate [EMHO‐i2], and ethane‐1,2‐diyl‐bis(9‐hydroxy‐10‐methacryloyloxy octadecanoate [EMHO‐i3]), was made by a three‐step reaction starting from esterification of oleic acid with ethylene glycol followed by epoxidation in a second step, and epoxy ring‐opening reaction with methacrylic acid in a third step. The new dimethacrylate obtained was photocured applying ultra‐violet technology to receive a neat polymer on the one hand and in the presence of a further methacrylate, such as 4‐(4‐methacryloyloxyphenyl)‐butan‐2‐one (MAPO) or methyl 9‐(1H‐imidazol‐1‐yl)‐10‐(methacryloyloxy)‐octadecanoate and methyl 9‐(methacryloyloxy)‐10‐(1H‐imidazol‐1‐yl)‐octadecenoate available as isomer mixture (MIMAO), on the other hand. The photopolymerization kinetic study applying photo‐differential scanning calorimetry technology showed that the addition of MAPO or MIMAO during photocuring resulted in an increase in both polymerization rate and final conversion on monomer in comparison with the homopolymerization of EMHO. As expected, the network density obtained by the study of the elastic modulus of the copolymers was reduced compared to the homopolymer caused by the presence of the methacrylate MAPO or MIMAO comprising only one polymerizable functional group. The crosslinked polymer films contain high gel content. Those films made by using an excess of MAPO showed a glass transition above room temperature caused by the aromatic ring comprising in MAPO. High contact angle values for water indicate the high hydrophobicity of the crosslinked polymer films that is attributed to the long alkyl chains contained in the bio‐based dimethacrylate. The copolymer made from the bio‐based dimethacrylate with MAPO excess may be interesting for application as a water‐repellent coating for surface protection and protection against corrosion.

Synthesis and photoinitiated polymerization of new ionic liquid methacrylates

“…The presence of the methacrylate may cause chain extension during the dimethacrylate crosslinking polymerization resulting in polymer networks with lower crosslink density, and therefore, higher mobility resulting in higher conversion. A similar effect was recently also found for crosslinking of bio‐based dimethacrylates in the presence of a bio‐based methacrylate 27 …”

“…The room temperature ionic liquid methacrylate ILMA‐B‐NTf 2 was selected for investigation of the photoinitiated polymerization in bulk using bis‐4‐(methoxybenzoyl)diethylgermane as photoinitiator (Scheme 3). The bis‐4‐(methoxybenzoyl)diethylgermane is a highly efficient photoinitiator as shown, for example, during investigation of photoinitiated polymerization of methacrylates comprising phenyl moieties and bio‐based methacrylates 26,27 . Further room temperature ionic liquid methacrylates comprising a variation of the alkyl substituent at the nitrogen and NTf 2 as anion (ILMA‐M‐NTf 2 , ILMA‐E‐NTf 2 , ILMA‐P‐NTf 2 , and ILMA‐H‐NTf 2 ) were included in the experiments as well because all appear as liquid at the polymerization temperature of 40°C.…”

“…A similar effect was recently also found for crosslinking of bio-based dimethacrylates in the presence of a bio-based methacrylate. 27…”

“…Yield and melting point (mp) or glass transition temperature (T g ) of the ionic liquid methacrylates (N-[2-(methacryloyloxy)ethyl]-N,N-dimethyl-N-butyl-ammonium ionic liquids comprising iodide (ILMA-B-I), bis(trifluoromethylsulfonyl) imide (ILMA-B-NTf 2 ), tris(pentafluoroethyl)trifluorphosphate (ILMA-B-FAP), triflate (ILMA-B-TFl), and trifluoroacetate (ILMA-B-TFAc) as anion, see Scheme 1), ionic liquid dimethacrylates (1,4-bis-(N,N-dimethyl-N-2-methacryloyloxyethyl ammonio) butane comprising iodide (ILDiMA-I), bis(trifluoromethylsulfonyl)imide (ILDiMA-NTf 2 ), tris(pentafluoroethyl)trifluorophosphate (ILDiMA-FAP), triflate (ILDiMA-TFl), and trifluoroacetate (ILDiMA-TFAc), see Scheme 2), and ionic liquids (1-butyl-3-methylimidazolium comprising chloride (BMImCl), bis(trifluoromethylsulfonyl)imide (BMImNTf 2 ), tris(pentafluoroethyl)trifluorophosphate (BMImFAP), triflate (BMImTFl) or trifluoroacetate (BMImTFAc) as anion) that were synthesized in this work ,27 Further room temperature ionic liquid methacrylates comprising a variation of the alkyl substituent at the nitrogen and NTf 2 as anion (ILMA-M-NTf 2 , ILMA-E-NTf 2 , ILMA-P-NTf 2 , and ILMA-H-NTf 2 ) were included in the experiments as well because all appear as liquid at the polymerization temperature of 40 C.The photo-DSC curve obtained for the photoinitiated polymerization of the room temperature ionic liquid methacrylate ILMA-B-NTf 2 shows a strong exothermic signal at short irradiation time (Figure1A). The maximum of the polymerization rate (R p max ) is about 0.04 s À1…”

Crosslinked Polymers Based on Monomers Derived from Renewable Resources and Their Application Potential

“…Furthermore, several bio-based linear aliphatic, aromatic, and cycloaliphatic compounds have been successfully converted into (meth)acrylates that are interesting monomers for manufacturing of polymers. [7][8][9][10][11][12][13][14] Among these bio-based monomers is a new dimethacrylate synthesized in three steps as shown in Scheme 1. The synthesis starts with esterification of oleic acid with ethylene glycol, it continues with epoxidation of the two double bonds of the ethylene dioleate, and ring opening reaction of the resulting diepoxy compound with methacrylic acid is the final step.…”