TECHNOLOGY FOCUS - CERAMICS AND GLASS - Preferred Components: The composite sheet further comprises glass fillers. The glass fillers are present at 60-300 parts by weight. The glass fillers comprise at least one of glass fiber cloth, glass fabric, unwoven glass cloth, glass mesh, glass beads, glass powder and glass flakes.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (Claimed): Preparing (I) comprises: preparing cyclohexenyl oxetane ether by reacting cyclohexenyl methanol and an oxetane compound of formula (II); and oxidizing the cyclohexenyl oxetane ether.R1 = H, methyl or ethyl; andX = Cl, Br, I, CH3C6H4SO3 or CF3SO3.    TECHNOLOGY FOCUS - POLYMERS - The binder is formed: using (I) and a cation polymerizable compound; or using (I) and a cationic initiator. The cation polymerizable compound comprises at least one of an epoxy group-containing compound, an oxetane group-containing compound, a vinyl ether group-containing compound and a caprolactone group-containing compound. The binder has a difference in index of refraction of less than or equal to 0.01 from the glass filler. The composite sheet has a glass transition temperature of greater than or equal to 200 degrees C. The substrate has a coefficient of thermal expansion of 30 parts per million/ degrees C or less as measured by a thermomechanical analyzer at 5 degrees C/minute at 30-250 degrees C. EXAMPLE - Sodium hydride (6.4 g) and dimethylformamide (150 ml) were added in a flask (500 ml) and stirred. After temperature was lowered using an ice bath, cyclohexenyl methanol (15 g) was slowly added to the mixture and stirred at room temperature for 15 minutes. Then the temperature was lowered using the ice bath again, an oxetane chloride (14.5 g) was slowly added to the mixture for 10 minutes and stirred at room temperature for 2 hours. After completion of reaction, water was added slowly to the product to remove the activity of remaining sodium hydride. Magnesium sulfate was added into an organic layer, filtered and the solvent was eliminated using an evaporator to obtain a colorless liquid of cyclohexenyl oxetane ether (93%). The obtained cyclohexenyl oxetane ether (20 g) was stirred in methylene chloride (50 ml) in the flask (250 ml) at room temperature for 5 minutes. A solution obtained by dissolving 77% of m-chloroperoxybenzoic acid (27.4 g) in methylene chloride (100 ml) was slowly added to the mixture for 30 minutes, and then heated and refluxed for 3 hours. After completion of reaction, temperature was lowered to room temperature, and the product was then filtered and the organic layer was added with a potassium carbonate solution. Magnesium sulfate was added into the organic layer, filtered and the solvent was removed using the evaporator and to obtain 3-(3-methyl-oxetan-3-ylmethoxymethyl)-7-oxa-bicyclo(4.1.0)heptane.