本研究將分子量1000及1800的聚二甲基矽氧烷二醇（polydimethylsiloxane diol，PDMS）作為軟鏈節，與4,4'-二苯甲基二異氰酸鹽（4,4'-diphenylemthane dissocyanate，MDI）、1,4-丁二醇（1,4-butanediol，1,4-BD）合成出兩系列矽氧烷-聚氨基甲酸酯共聚合體。由DSC測試顯示共聚合體的軟鏈節玻璃轉移溫度（Tgs）與其轉移區寬度（ΔB）均不隨硬鏈節含量的增加而產生改變。但不同軟、硬鏈節組成的共聚合體，其軟鏈節玻璃轉移區的熱焓（heat capacities，ΔCp）會產生變化，在0.195~0.411 J/g℃之間，且分子量1000與1800的純PDMS預聚合體（PDMS prepolymer）的熱焓（ΔCp0）分別為0.647與0.571 J/g℃。熱焓的改變是因為PDMS預聚合體的末端基具有強極性醚基，而此軟鏈節極性基團導致軟硬鏈節間產生互溶，因而共聚合體有不同的ΔCp/ΔCp0值。由DMA測試中，共聚合體軟鏈節的tan δ值也證實軟硬、鏈節間有互溶的現象出現。共聚合體的機械性質與軟、硬鏈節的含量或鏈長有直接關係，硬鏈節呵補強軟鏈節及增強軟、硬鏈節間的界面厚度，所以主導了共聚合體的機械性質強弱。

　　　　　Two series of siloxane-urethane copolymers were prepared from polydimethylsiloxane diol (PDMS) with a molecular weight 1000 or 1800 which was used as a soft segment, 4,4'-dephenylmethane diisocyanate (MDI) and 1,4-butanediol (1,4-BD). Differential scanning of calorimetry (DSC) demonstrated that the position (Tgs) and breadth (ΔB) of soft-segment glass transition of copolymers remained constant as the hard-segment content increased. Heat capacities at soft segment glass transition of copolymer (ΔCp) were 0.195~0.411 J/g℃ and heat capacities of PDMS prepolymer (ΔCp0) were 0.571~0.647 J/g℃, leading to the various ΔCp/ΔCp0 ratios. The various heat capacities were attributed to the polar ether end-group of PDMS prepolymer. The result confirmed that the ether end-group of the soft segment led to interfacial mixing between soft and hard segments. The tan δ of the soft segment determined by dynamic mechanical testing (DMA) also identified the mixing of soft and hard segment. The mechanical properties of siloxane-urethane copolymers were directly related to either soft and hard segment content or the chain length. The hard segment that reinforced the soft segment and interfacial thickness between soft and hard segment dominated the mechanical properties.