Preparation Of Undecylenic Acid Based Copolymer And Its Application In Emulsion Polymerization

Acrylate emulsion is one of the most widely used emulsions in the industrial production.The modification the acrylate emulsion with renewable resources to prepare bio-based emulsion has suggested to be beneficial to the environment.Undecylenic acid(UA)extracted from castor oil has showen several interesting properties such as its aboundance,bio-degradability and environmentally friendliness.Therefore it has the potential to be used to modify acrylate emulsion.In this study,UA/ methyl methacrylate(MMA)copolymer emulsion was prepared by emulsion polymerization of UA and MMA.The UA can act as a soft and functional monomer as compared to the acrylic acid.Additionally,UA and maleic anhydride(MAH)were copolymerized to prepare the copolymer(UMA)with carboxyl and anhydride functional group.A macromolecular emulsifier UMA-DA was then synthesized by the esterification of UMA copolymer using dadecanol(DA),which was used for the emulsion polymerization of UA and MMA after saponification.Undecylenic acid/methyl methacrylate(UA/MMA)copolymer emulsion was prepared by emulsion polymerization.The effects of the addition of UA to copolymer and initiator dosage on the polymerization process and polymer properties were studied.The results indicated that UA was involved in the copolymerization reaction with MMA.The number average molecular weight(Mn)of copolymer decreased significantly from 203 000 to 147 000 g/mol,as the increase of the amount of UA from 10% to 30%.Furthermore,the polymerization rate decreased as well.The UA/MMA copolymer has a lower glass transition temperature(Tg)compared to MMA polymer,and the thermal stability of the copolymer also improved with increased of the dosage of UA.During the emulsion preparation,as the amount of initiator increased,the number average molecular weight of UA/MMA polymer decreased and the conversion rate increased.Particle diameter test showed that the volume average particle diameter of emulsion particles was about 120 nm and it increased slightly with the addition of UA.Viscosity test showed that the viscosity of copolymer emulsions was 10-15 m Pa·s.UA/MAH copolymer was prepared by the precipitation polymerization.FT-IR and 13 C NMR analysis indicated that UA and MAH copolymerized successfully.The data of GPC and conversion showed that with the decrease of the n(UA)/n(MAH),the number average molecular weight and molecular weight distribution index of polymer decreased,the conversion increased firstly and then declined slightly.Increasing the amount of initiator and reaction temperature facilitated the copolymerization but the relative molecular mass of UMA copolymer declined significantly.In addition,the increase in the monomer concertation can effectively improve the conversion and number average molecular weight of copolymer.Anhydride content analysis showed that the anhydride content firstly increased and then decreased as the increase of MAH.According to the conversion of monomers,the optimal molar ratio of UA to MAH is 40/60 in the reaction system.The DSC result indicated that as the molar ratio of UA to MAH decreased,the Tg of copolymer firstly increased and then declined,which is basically consistent with the change of anhydride content.TGA data showed that the copolymer has a good heat resistance.UMA-DA copolymer were prepared by the esterification of UMA using dadecanol(DA),and the copolymer was then used as a macromolecular emulsifier in the emulsion polymerization after saponification.FT-IR analysis showed that the esterification between UMA and DA occurred successfully.The CMC value of saponified UMA-DA was determined by a surface tension method.The CMC value was 9.55 g/L and the corresponding surface tension(γCMC)was 23.04 m N/m.Furthermore the emulsifying capacity of UMA-DA for UA and MMA mixed monomer was tested as well.The results showed that as compared to the commercial emulsifier AOT and SDS,the emulsifying capacity of UMA-DA was lower than AOT but superior to SDS.UMA-DA macroemulsifier was used to prepare UA/MMA copolymer emulsion.The effect of UMA-DA dosage on the properties of emulsion was investigated.The results showed that under the same monomer ratio,when the UMA-DA dosage increased from 6% to 12%,the monomer conversion rate firstly increased and then slightly decreased.Moreover the gelation rate gradually declined.The emulsion particle size and particle size distribution index tend to increase trend.In addition,the number average molecular weight slightly.increased The water absorbency of the latex film under different amounts of UMA-DA was measured.The results showed that as the UMA-DA content increased from 6% to 12%,the water absorption rate of the latex film decreased.Compared the emulsion that prepared expect with UMA-DA and AOT,it was observed that the conversion rate of monomers under the two emulsifying systems was similar.The gel rate,particle size and water absorption of emulsion prepared with UMA-DA are higher than the emulsion prepared with AOT as an emulsifier.However,by adjusting the dosage of UMA-DA,it has the potential to be used in UA/MMA emulsion polymerization or other emulsion system.