by sol - gel reaction , phosphorus - containing polysilsesquioxanes are synthesized . the phosphorus and silicon containing therein work as of flame retardants of the polymer so that the material has excel lent thermal properties and flame retardance . refer to step s 10 in fig1 , add epoxy resin containing siloxane group into ladder - like phosphorus - containing polysilsesquioxanes , together with tetraethoxysilane and catalyst for performing hydrolysis reaction and condensation reaction . then take step s 12 , add curing agent . next , refer to step s 14 , take a curing process , step s 16 run a drying process , and step s 18 take a sintering process . moreover , the epoxy resin containing siloxane group is ipts ( 3 - isocyanatopropyltriethoxysilane )- epoxy resin . refer to fig2 , a manufacturing method for the ipts - epoxy resin includes following steps : step s 20 , the dgeba ( diglycidylether of bisphenol a ) type epoxy is dissolved in tetrahydrofuran ( thf ). then step s 22 , add ipts ( 3 - isocyanatopropyltriethoxysilane ) into the dgeba type epoxy solution . next step s 24 , add catalyst into the solution to allow a reaction to take place . refer to step s 26 , ipts - epoxy resin solution is obtained . furthermore , refer to fig3 , a manufacturing method for ladder - like phosphorus - containing polysilsesquioxanes includes following steps : step s 30 : prepare water / dppetes ( 2 - diphenylphosphino ) ethyltriethoxysilane mixture in ratio of 3 : 1 ; step s 32 : add dppetes / lsopropylalcohol / tetrahydrofuran in mole ratio 1 : 6 . 23 : 1 . 67 into the solution ; step s 24 , keep stirring until the mixture is clear , add catalyst to form a gel . prepare precursors of epoxy resin modified by 3 - isocyanatopropyltriethoxysilane ( ipts ) so as to get epoxy resin with siloxane side chain . dissolve 10 g dgeba - type epoxy resin in 10 g thf and the solid content is about 50 wt %. then 4 g ipts ( a nco equivalent weight of 247 g ) is slowly added into epoxy resin solution so that nco group on ipts reacts with hydroxy group on epoxy resin . tea is added into the solution also as a catalyst . the mixture is stirred by a magnetic bar at the temperature of 60 degrees celsius and is recycled so as to maintain the concentration . fourier - transform infrared spectroscopy ( ftir ) is used to detect reactions of the group . for reacting completely , it take about 20 to 24 hours and get ipts - epoxy solution . refer to fig4 , a chemical reaction is disclosed . put 5 g ( 2 - diphenylphosphino ) ethyltriethoxysilane ( dppetes ) into a 20 mg sample vial and then add h2o / dppetes in ratio of 3 : 1 into the sample vial . next add dppetes / lsopropylalcohol ( ipa )/ tetrahydrofuran ( thf ) in mole ratio 1 : 6 . 23 : 1 . 67 into the mixture and stir the solution until it is clear . add hydrochloric acid as a catalyst to make ph of the solution become 2 . put the solution into an aluminum plate at the room temperature for 48 hours to make the solution become colloidal . then keep it at the temperature of 80 degrees celsius for 24 hours . the sample is vacuumed at the temperature of 200 degrees celsius for 24 hours . please refer to fig5 , a chemical reaction is disclosed . the ipts - epoxy resin is respectively added 3 %, 6 %, 9 %, and 12 % ladder - like dppetes and then 9 % teos is added in . use hydrochloric acid as catalyst and stir the mixture at the room temperature for an hour so as to perform hydrolysis reaction and condensation reaction . next add curing agent - 4 , 4 - methylenedianline ( ddm ) that is dissolved in thf in advance . keep the solution at the room temperature for one day . then heat the mixture at the temperature of 80 degrees celsius for 2 hours and at the temperature of 160 degrees celsius for 12 hours . the modified epoxy is reacted completely after 8 hours . thus by a long reaction time , the present invention prevent incomplete reaction . moreover , optimum concentration of ladder - like polysiloxane and its monomer is 9 wt % that achieves best efficiency and lower cost . when being measured by thermal properties test , the tga data shows that char yield is improved to 30 %, thermal degradation rate is obviously lowered and 30 limiting oxygen index ( loi ) indicate that epoxy nanocomposites possess better properties . this also means nanocomposites material possesses excellent thermal stability and flame retardance . by doping , protective effects are formed due to low surface potential of polysiloxanes . as to modified resin , the flame retardance is caused by pu - type soft segment . during thermal properties of ladder - like silsesquioxane , a reactive - type system has excellent thermal stabilities while in additive - type system , retardance is resulted from strong siloxane bond generating from siloxane bond on nco segment reacting with ladder - like material or monomer . in optical tests , polysilsesquioxanes epoxy resin according to the present invention has excellent optical transparency in visible region ( 400 nm ˜ 800 nm ). the present invention provides an excellent material for future development of optical elements and high performance nano - scale coating material . in structure research , x - ray image shows that epoxy resin nanocomposite materials are amorphous and there is a consistency of the spectrum obtained because there is no big difference in entanglements . the excellent transparency of the resin of the present invention results from no phase separation and amorphous structure . furthermore , in sem ( scanning electron microscopy ) research , the organic / inorganic polysilsesquioxanes nanocomposite material has good compatibility without phase separation problem . in si - mapping , it is further proved that inorganic phase ( si — o — si ) is distributed well and homogeneously . in the tem ( transmission electron microscope ) image , the silsesquioxanes is in nano - scale ( most of their size is less than 100 nm ) and there is no aggregation problem . although they are distributed irregularly , there is no phase separation . thus epoxy materials formed by the present invention are obviously composite materials in nano - scale . in applications , such material with high thermal stability and high transparency is applied to painting paint for home decoration , protective coatings and protective layers of optical elements . additional advantages and modifications will readily occur to those skilled in the art . therefore , the invention in its broader aspects is not limited to the specific details , and representative devices shown and described herein . accordingly , various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents .