Chain extended vinyl aniline modified cyclohexanone formaldehyde resin

Purpose - The purpose of this paper was as follows. The in situ chemical oxidation (ICO) of vinyl aniline modified cyclohexanone formaldehyde resin (CFVAnR) in the presence of potassium persulphate salt (K₂S ₂O₈) was accomplished in dimethyl sulphoxide (DMSO) solutions at 35°C and 70°C. The chemical composition and structure of the oxidized CFVAnR were characterised by nuclear magnetic resonance (1H-NMR) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, DSC, TGA and SEM. Design/methodology/approach - The reactive vinyl and amine groups of the cyclohexanone formaldehyde resin were reacted in the presence of potassium persulphate. CFVAn resin was dissolved in DMSO inside a round bottom flask immersed in a water bath thermostated at reaction temperature of 35°C and 70°C, respectively. Solution of K₂S₂O₈ was prepared in DMSO and this was added into the resin solution. Findings - It was shown that the vinyl groups in the resin were reacted easily with persulphate salt to obtain chain extended CFVAnR (CECFVAnR). The oxidised 4-vinyl aniline modified cyclohexanone-formaldehyde resin has solublity in organic solvents. Research limitations/implications - The reaction mixture must be stirred continuously. Temperature should be controlled to prevent the thermal polymerisation of vinyl group and higher branching of amino groups. The persulphate ion (S₂O^2-₈ ) has a standard oxidation potential, but when activated by heat (40-60°C). Furthermore, sulphate radical can react with water or hydroxide to produce hydroxyl radical (-OH). When persulphate is used for in situ chemical oxidation (ISCO) application at relatively low temperatures (e.g. <20°C), the oxidation reactions are usually less aggressive due to a slow generation rate of SO ^-₄ . Practical implications - This study provides technical information for the synthesis of chain extended resins. The modified resins contain vinyl groups. The chemical radical system has been used to polymerise these vinyl groups and resins with much higher molecular weight might be produced. The resins may also promote the adhesive strength of a coating and corrosion inhibition to metal surfaces of a coating. Social implications - This resin will be used for the preparation of AB- and ABA-type block copolymers. These block copolymers may exhibit different properties due to incorporation of ketonic resins into the block copolymer structure. Originality/value - Chain extended CFVAnR (CECFVAnR) was synthesised by one step reduction-oxidation reaction, at 35°C (CECFVAnR1) and 70°C (CECFVAnR2) in the presence of potassium persulphate salt. These soluble resins may overcome difficulties in the applications of polymers and open new application areas. Therefore, the chain extended vinyl aniline modified resin may find a number of new application areas as well as existing UV curable resin and polymer applications.