Isophorone diisocyanate(IPDI), poly(tetramethylene glycol)(PTMG), dimethylol propionic acid(DMPA)를 출발물질로 하여 NCO terminated prepolymer가 합성되었다. 이 prepolymer의 NCO기를 실란으로 capping하기 위해 다양한 실란커플링제인 methyltrimethoxysilane(MTMS), glycidoxypropyl trimethoxysilane(GPTMS), methacryloxypropyl trimethoxy-silane(MPTMS), aminopropyl triethoxy-silane(APS)이 첨가되었다. 제조된 용액의 평균 입경은 실란커플링제가 첨가되면서 증가하였다. 또한 실란커플링제인 GPTMS, MPTMS, APS의 첨가는 코팅 막의 연필경도를 향상시킬 수 있었으나, MTMS의 첨가는 코팅 막의 연필경도를 향상시킬 수 없었다.

NCO terminated polyurethane prepolymers were synthesized from isophorone diisocyanate(IPDI), poly (tetramethylene glycol)(PTMG) and dimethylol propionic acid(DMPA). Subsequently, waterborne polyurethanes were prepared by capping the NCO groups of polyurethane prepolymers with different types of silane coupling agents, such as methyltsimethoxysilane(MTMS), glycidoxypropyl trimethoxysilane(GPTMS), methaeryloxypropyl trimethoxysilane(MPTMS) and aminopropyl triethoxysilane(APS). The avenge particle size of the waterborne polyurethane solutions was increased by adding silane coupling agents. Also, the coating films prepared from GPTMS, MPTMS and APS, exhibited better pencil hardness than those from pure waterbome polyurethane. On the other hand, the coating films from MTMS did not show an improved pencil hardness than those from pure waterbome polyurethane.