Surface Self-cleaning Polymers Of Waterborne Terpene-based EP/PU Composite Modified With Nano-SiO₂ And Polysiloxane

In this paper,according to the“Lotus Effect”,surface hydrophobic self-cleaning polymers of waterborne terpene-based EP/PU were prepared from the terpene based epoxy resin?TME?modified with nano-SiO₂ and polysiloxane.This research focused on the utilization of biomass renewable resources and the nano self-cleaning materials.The main topics of this thesis are as follows:?1?synthesis and characterization of polyols,and the particle size distribution,particle morphology,stability of the polyol dispersion;?2?morphology,mechanical properties and thermal properties of the composite films;?3?effects of polysiloxane and nano-SiO2 on the properties of the composite products.The purpose of this study is to provide theoretical and technological basis for high-efficiency,high value of the renewable resource and the functional application of biomass based polymer materials.1.The TME-based polyol?T-N?was prepared with TME and neopentyl glycol.Then the T-N was modified with hydroxypropyl terminated polysiloxane?HTPDMS?,2,4 tolylene diisocyanate and 2,2-bis?hydroxymethyl?propionic acid giving an anionic polysiloxane-modified polyol?ASTP?dispersion.The best synthesis condition of ASTP was confirmed by studying about reaction influence factors.ASTP dispersion was obtained at the conditions as follows:DMPA and TDI were mixed with the molar ratio 1:2,and reacted at 56?for 3 hours with acetone as reaction solvent?the amount of solvent was 1.5² times based on the reactants quality?.Then the reaction was continued for 4 hours after adding HTPDMS and T-N.The obtained ASTP dispersion showed good stability when the dosage of HTPDMS was 0¹5%of T-N by weight.2.Nonionic polyol?NSTP?dispersion was prepared by modifying TME with polyethylene glycol and HTPDMS.Suitable synthesis condition of NSTP was confirmed by studying on the factors of synthesis reaction.When reacted at 100-110?for 1 h,good quality product could be obtained from polyethylene glycol with molecular weight of 4000 and amount of 12%by weight based on the weight of TME,and HTPDMS with molecular weight of 2000,in the catalysis of boron trifluoride diethyl etherate with the amount of 1%based on the weight of TME.The obtained NSTP was semitransparent yellow solid with hydroxyl value of 70-200mg/g.NSTP dispersion was milk-white liquid with solid content of 30%and viscosity of50¹00 mPa·s.The NSTP could be dispersed stably in water when the dosage of HTPDMS was 10²0%of TME by weight.3.Waterborne EP/PU composite polymers were prepared from polysiloxane modified TME-based polyol dispersions and hydrophilically modified hexamethylene dissocyanate?HDI?tripolymer.The composite polymers had only one T_g in scanning temperature from-40 to120?,which indicated the modified polyols had good compatibility with HDI.The silicon concentration in the uppermost surfaces of the sample was higher than the polymer-substrate interface.This result implied that the HTPDMS segments enriched at the polymer-air interface and a hydrophobic film surface was formed.When the amount of the HTPDMS with molecular weight of 2000 reached 10%by weight based on the weight of T-N,siloxane content in the uppermost surfaces was saturated and the contact angle increased to about 95°.The formation of“sea-island structure”could correspond to the microphase separation between HTPDMS segment and the resin matrix.This microphase separation caused a destruction of the film compactness and led to a decrease of glass transition temperatures of the polymers.4.The superhydrophobic surface was formed from building rough micro/nano structure on the surface of HTPDMS modified waterborne EP/PU composite polymers.Nano-SiO₂ particles were prepared by St?ber method with TEOS as precursor,ammonia as catalyst and ethanol as solvent.Then,TMES was used as hydrophobic modification agent,and the hydrophobic nano-SiO2 was obtained via forming a layer of hydrophobic methyl groups covering the spherical SiO₂.The superhydrophobic composite coating was successfully fabricated by using polysiloxane modified waterborne terpene EP/PU dispersion as low surface energy material,and hydrophobic nano-SiO2 for building micro/nano rough structure on the polymer surface.The effects of SiO₂ content on the surface morphology and hydrophobicity were investigated.When the amount of the hydrophobic nano-SiO2 reached 15%by weight based on the solid content of composite emulsion,the morphology of the coating surface exhibited random micro/nanostructure and the contact angle reached 153.4°.The wetting behavior of the coating surface exhibited good superhydrophobicity,meeting the requirements of the self-cleaning property.