Observation of strong nano-effect via tuning distributed architecture of graphene oxide in poly(propylene carbonate)

For optimum reinforcement in polymer nanocomposite, a critical challenge is to realize the full 'nano-effect' of nanofillers at a high content, which is largely hindered by the strong tendency to aggregation of nanofillers. Here, by using a solvent-exchange and solution casting approach, we could incorporate a high-content graphene oxide (GO) into a soft biodegradable CO2-based poly(propylene carbonate) (PPC) up to 20 wt% with excellent dispersion. Based on this, the distributed architecture of GO could be tuned from a 'GO dotted dispersion' and 'GO network' to strong 'GO co-continuous structure' with increasing GO content. As a result, a very strong 'nano-effect' of GO in the PPC matrix was observed: (1) the glass transition temperature of PPC was improved from 25 to 45 ° C for slightly confined molecular chains, and even to 100 ° C for highly confined ones; (2) the modified PPC showed drastically enhanced high-temperature mechanical properties, comparable to those of traditional polymers such as polypropylene (PP) and biopolymer poly(lactic acid) (PLA); and (3) such modified PPC exhibited an exciting solvent resistance compared to neat PPC. Our work provides an example to improve the high-temperature properties of a polymer via formation of filler co-continuous structure.