Polymorphism is an important factor associated with the cellulose nanomaterial properties. In this study, cellulose fibers (CFs) were efficiently isolated from waste Tetra pak packages, and cellulose I and II nanocrystals were produced by treatment of CFs with 64% sulfuric acid and controlling the reaction time from 15 to 30 min. Cellulose I (CI) was partially converted to cellulose II (CII) within 15 min and the resulting cellulose nanocrystal product (i.e. CNC15) contained 93.2% CII. Further extending the hydrolysis time decreased the CII content of CNC20 to 25.5% and CNC30 was completely CI without CII. CNC15 (285.1 ± 120.7 nm long, 50.6 ± 16.5 nm wide, 0.64 at% sulfur) was much thicker, slightly longer, less thermal stable and contained more sulfate groups than CNC30 (207.2 ± 77.8 nm long, 23.2 ± 7.8 nm wide, 0.34 at% sulfur). CNCs with controllable allomorph may have potentially diverse applications.

多态性是与纤维素纳米材料性能相关的重要因素。在这项研究中，有效地从废弃的利乐包装中分离了纤维素纤维（CFs），并通过用64％硫酸处理CFs并将反应时间控制在15至30分钟来生产纤维素I和II纳米晶体。纤维素I（CI）在15分钟内部分转化为纤维素II（CII），所得纤维素纳米晶体产品（即CNC15）包含93.2％CII。进一步延长水解时间，将CNC20的CII含量降至25.5％，而CNC30在没有CII的情况下完全为CI。CNC15（285.1±120.7 nm长，50.6±16.5 nm宽，硫0.64 at％）比CNC30（207.2±77.8 nm长，23.2±7.8 nm宽，0.34）厚得多，稍长，热稳定性较差并且包含更多的硫酸根基团硫含量％）。