Poly(styrene-b-isobutylene-b-styrene) triblock copolymer (SIBS), a kind of thermoplastic elastomer with biocompatibility and biostability containing fully saturated soft segments, could be synthesized via living cationic copolymerization. A novel poly[(styrene-co-methylstyrene)-b-isobutylene-b-(styrene-co-methylstyrene)]-g-polytetrahydrofuran (M-SIBS-g-PTHF) block graft copolymer was prepared to increase the polarity and service temperature of SIBS by grafting polar PTHF segments onto SIBS. A series of the above block graft copolymers with average grafting numbers from 2 to 6 and molecular weights of PTHF branches ranging from 200 g·mol⁻¹ to 4200 g·mol⁻¹ were successfully synthesized via living cationic ring-opening polymerization of tetrahydrofuran (THF) coinitiated by AgClO₄. The introduction of PTHF branches led to an obvious microphase separation due to thermodynamic incompatibility among the three kinds of segments of polyisobutylene (PIB), polystyrene (PS) and PTHF. Moreover, the microphase separation promotes the rearrangement of PTHF branches to form the nanocrystallization-locked physically cross-linked network after storage at room temperature for 2 months, leading to insolubility of the copolymers even in good solvents. The melting temperature and enthalpy of PTHF nanocrystallization locked in hard domains of M-SIBS-g₅-PTHF-1.1k block graft copolymer increased remarkably up to 153 °C and 117.0 J·g⁻¹ by 23 °C and 11.6 J·g⁻¹ respectively after storage for long time. Storage modulus (G′) is higher than loss modulus (G″) of M-SIBS-g-PTHF block graft copolymer at temperatures ranging from 100 °C to 180 °C, which is much higher than those of the SIBS triblock copolymer. To the best of our knowledge, this is the first example of high performance M-SIBS-g-PTHF block graft copolymers containing segments of PIB, PS and PTHF with nanocrystallization-locked architecture.

聚（苯乙烯- b -isobutylene- b -苯乙烯）三嵌段共聚物（SIBS），一种具有生物相容性和含有完全饱和的软链段的生物稳定性的热塑性弹性体，可以合成通过活性阳离子共聚。一种新型的聚[（苯乙烯-共-甲基苯乙烯） - b -isobutylene- b - （苯乙烯-共-甲基苯乙烯）〕 -克-聚四氢呋喃（M-SIBS-克通过将极性PTHF链段接枝到SIBS上来制备嵌段共聚物（-PTHF），以提高SIBS的极性和使用温度。通过四氢呋喃的阳离子阳离子开环聚合反应，成功合成了一系列上述平均嵌段接枝数为2至6，PTHF支链分子量为200 g·mol ^-1至4200 g·mol ^-1的嵌段接枝共聚物（由AgClO ₄引发的THF）。由于聚异丁烯（PIB），聚苯乙烯（PS）和PTHF三种片段之间的热力学不相容性，PTHF支链的引入导致明显的微相分离。此外，微相分离促进了PTHF支链的重排，从而在室温下保存2个月后形成了纳米晶锁定的物理交联网络，即使在良好的溶剂中也导致共聚物不溶。锁定在M-SIBS- g ₅ -PTHF-1.1k嵌段接枝共聚物硬区中的PTHF纳米晶的熔化温度和焓显着提高，分别由23°C和11.6 J·g分别提高到153°C和117.0 J·g ^{-1 -1}分别存放较长时间后。在100℃至180℃的温度下，储能模量（G'）高于M-SIBS- g -PTHF嵌段接枝共聚物的损耗模量（G''），这远高于SIBS三嵌段共聚物的储能模量。据我们所知，这是含有纳米晶锁定结构的PIB，PS和PTHF链段的高性能M-SIBS- g -PTHF嵌段接枝共聚物的第一个示例。