The Preparation And Properties Of Hard Organic/Inorganic Hybrid Films With Silicon

Due to the low surface hardness, transparent plastic is easy to be scratched in use, whichmakes the loss of operation life and limits extended application. The surface scratch behaviorcan be reduced effectively through coating a hard protective film on it. The organic/inorganichard film can integrate good adhesion to substrate of organic film with excellent hardness ofinorganic film, which has become the hot study spot of hard film on plastic.The transparent and hard SiO₂/organosilicone hybrid coatings were prepared onpolycarbonate（PC） with tetraethoxysilane and organosiloxane as the main raw materials bysol-gel method. In order to improve anti-alkali corrosion properties, adhesion andenvironmentally friendly of the SiO₂/organosilicone hybrid materials, heat-curablesilicone/amine hybrid materials, polyester/SiO₂/organosilicone hybrid materials and UVcurable SiO₂/hyperbranched polyurethane acrylate hybrid materials were preparedrespectively. The relationship of composition, structure and properties of hybrid hard filmswith silicon was studied systemically. The detailed research contents and results weredescribed as follows:1. With tetraethoxysilane（TEOS） as inorganic precursor, methyltriethoxysilane（MTES）,dimethyldiethoxysilane（DMDES） and3-（methacryloxypropyl）trimethoxysilane（MAPTMS）as organic precursor, the heat-curable SiO₂/organosilicone hybrid coatings was synthesized bysol-gel method. When the molar ratio of SiO₂/organosilicone hybrid coating was n_TEOS:n_MTES:n_DMDES:n_MAPTMS=5:5:2:2, n_IPA/n_Si-OR=0.8, n_H2O/n_Si-OR=1.1, n_HAc/nSi-O=0.008, the gelation timeexceeded360days. The hybrid film had high hardness and good adhesion because linearSi-O-Si segmers were introduced into high-density crosslinked SiO₂network. The hybridfilms prepared in accordance with the optimized ratio had optimal properties withtransmittance of93.6%, pencil hardness of2H, adhesion of0degree. It was found that thehybrid coating had excellent thermal stability, which increases gradually with the decrease ofn（R）/n（Si） value. The contact angle of the hybrid coating to the water increased with theincrease of n（R）/n（Si） value and curing time. Higher light transmittance of hybrid coatingswas probably due to lower refractive index of hybrid coatings than that of the PC sheet. It wasalso considered that the hybrid coating reduces light reflection on the surface of the substrate. 2. The type of amine resin significantly affected the alkali resistance of the SiO₂/organo-silicone film. In comparison with part methoxymethyl and butoxymethyl melamine resin,Hexamethoxymethyl melamine resin（HMMM） had better durability and balance betweenhardness and flexibility for hybrid coatings. FTIR showed that the co-condensation betweenthe methoxymethyl groups in HMMM and the hydroxyl groups in SiO₂/organosilicone resin.The SiO₂/organosilicone resin formed more dense inorganic-organic network after HMMMmodified, resulted in NaOH and other small molecules not easy to penetrate into hybrid films.When the content of HMMM was2wt.%, SiO₂/organosilicone resin had best compatibilitywith HMMM and hybrid particles had regular morphology. The hybrid film was still smoothand had minimum transmittance loss of0.43%after immersion in NaOH solution for24h.3. A series of polyester/SiO₂/organosilicone hybrid coatings were synthesized throughcopolymerization and blending method between SiO₂/organosilicone resin and sulfonicgroup-containing polyester made from carefully selected proper monomers in my ownlaboratory. The polyester containing strong polarity of the sulfonic group, which not only toimprove the compatibility with SiO₂/organosilicone resin, but also improve the adhesion toPC, resulted in polyester/SiO₂/organosilicone coatings could be spread on PC without primer.The grafting rate of co-polymerizable resin is greater than that of the blends. The viscosity ofco-polymerizable and blending hybrid resin increased with polyester content increasing. Incomparison with blending method, co-polymerizable method had much stronger interactionsbetween organic phases and inorganic phases, resulting in higher crosslinking density, higherthermal stability and wear resistance for hybrid coatings. The extent of microphase separationand the surface roughness of the blending coatings became bigger. Obvious agglomerateswere observed for the blending coatings while those agglomerates were only observed for theco-polymerizable coatings at relatively high polyester content. The thermal decompositionprocess of the co-polymerizable sample followed one-order kinetics with the higher activationenergy of243kJ/mol. XRD studies showed that the co-polymerizable materials wasamorphous. EDS analysis showed that the silica particles could move towards the surface ofco-polymerizable coatings to lower free energies. The co-polymerizable coating had a lowersurface energy and better water resistance than the blends, and its surface free energy andwater absorption decreased with increasing of SiO₂/organosilicone content. 4. The modified silicone sol from TEOS and MAPTMS were used as inorganiccomponents and hyperbranched polyurethane acrylate（HBPUA） were used as organiccomponents for preparing a series of UV-curable HBPUA/（MAPTMS-SiO₂） hybrid coatings.The results showed that HBPUA/（MAPTMS-SiO₂） hybrid films hand good interfacialcompatibility and SiO₂were well distributed in organic matrix. The stability ofHBPUA/（MAPTMS-SiO₂） hybrid coatings were higher than that of PUA/（MAPTMS-SiO₂）hybrid coatings. The HBPUA/（MAPTMS-SiO₂） hybrid film became transparent, dense, nocracks and microphase separation after UV curing. However, the gel particles of hybridcoatings increased with the content of inorganic component increasing. The terminalconversion degree of C=C bonds of HBPUA/（MAPTMS-SiO₂） hybrid coatings were higherand thermal stable was better than those of PUA/（MAPTMS-SiO₂） hybrid coatings. The TgofHBPUA/（MAPTMS-SiO₂） hybrid coatings increased with the content of inorganic componentand UV curing time increasing. When the content of modified silicone sol （nTEOS: nMAPTMS=1:2） was30wt.%,1,6-hexanediol diacrylate was20wt.%, composite initiators （Irgacure184+TPO） was3wt.%, the gel time of HBPUA/（MAPTMS-SiO₂） hybrid coatings exceed180days.After UV curing for4min, hybrid coatings had optimal properties with transmittance of92.8%, pencil hardness of4H, adhesion of0degree, flexibility of3mm, impact strength of46kg·cm and abrasion resistance of only17.5mg.