Polymer surfaces are believed to have high mobility, and the glass transition temperature (T_g) of these surfaces is significantly decreased compared to that of the bulk. In this study, we prepared a molecularly stepped poly(methyl methacrylate) (PMMA) substrate by thermally nanoimprinting a PMMA plate with an atomically stepped sapphire substrate and PMMA isolated chains deposited on it by the Langmuir-Blodgett technique. The imprinted PMMA surface with a step height of ~0.2 nm and isolated PMMA chains deposited on it could be observed at the molecular level up to the PMMA bulk T_g by in situ high-temperature atomic force microscopy, indicating that the PMMA surface and the PMMA chains deposited on it have thermal stability close to the bulk PMMA T_g and that no significant decrease in T_g was observed. The significant thermal stability of the surface of the imprinted PMMA substrate and deposited PMMA chains is unexpected and differs from the results based on our present understanding of the polymer surfaces.

聚合物表面被认为具有高迁移率，与本体相比，这些表面的玻璃化转变温度 ( T _g ) 显着降低。在这项研究中，我们通过热纳米压印 PMMA 板制备了分子阶梯式聚（甲基丙烯酸甲酯）（PMMA）基底，该板具有原子阶梯式蓝宝石基底和通过 Langmuir-Blodgett 技术沉积在其上的 PMMA 隔离链。用〜0.2纳米的台阶高度并分离PMMA链压印PMMA表面沉积在其上可以在分子水平到PMMA散装观察Ť_克原位高温原子力显微镜，表明PMMA表面和沉积在其上的 PMMA 链具有接近本体 PMMA 的热稳定性T _g并且没有观察到T _{g 的}显着降低。压印的 PMMA 基材和沉积的 PMMA 链的表面显着的热稳定性是出乎意料的，与基于我们目前对聚合物表面理解的结果不同。