From the point of better biocompatibility and sustainability, biobased shape memory polymers (SMPs) are highly desired. We used 1,3-propanediol, sebacic acid, and itaconic acid, which have been industrially produced via fermentation or extraction with large quantities as the main raw materials for the synthesis of biobased poly(propylene sebacate). Diethylene glycol was used to tailor the flexibility of the polyester. The resulted polyesters were found to be promising SMPs with excellent shape recovery and fixity (near 100% and independent of thermomechanical cycles). The switching temperature and recovery speed of the SMPs are tunable by controlling the composition of the polyesters and their curing extent. The continuously changed switching temperature ranging from 12 to 54 °C was realized. Such temperature range is typical for biomedical applications in the human body. The molecular and crystalline structures were explored to correlate to the shape memory behavior. The combination of potential biocompatibility and biodegradability of the biobased SMPs makes them suitable for fabricating biomedical devices.

To fully exhibit the potentials of the fascinating characteristics of graphene oxide (GO) in polymer, the achievement of strong interface interactions and fine dispersion of GO in the hybrids is essential. In the present work, the elastomeric hybrids consisting of GO sheets are fabricated by utilizing butadiene–styrene–vinyl pyridine rubber (VPR) as the host through co-coagulation process and in situ formation of an ionic bonding interface. The VPR/GO composites with a normal hydrogen bonding interface are also prepared. The mechanical properties and gas permeability of these hybrids with an ionic bonding interface are obviously superior to those of the composites with a hydrogen bonding interface. With the ionic interfacial bonding, inclusion of 3.6 vol% of GO in VPR generates a 21-fold increase in glassy modulus, 7.5-fold increase in rubbery modulus, and 3.5-fold increase in tensile strength. The very fine dispersion of GO and the strong ionic interface in the hybrids are responsible for such unprecedented reinforcing efficiency of GO towards VPR. This work contributes new insights on the preparation of GO-based polymer hybrids with high performance.

State-of-the-art processes cannot achieve rubber/multi-walled carbon nanotube (MWCNT) composites with satisfactory performance by using pristine MWCNTs and conventional processing equipment. In this work, high performance rubber/MWCNT composites featuring a combination of good mechanical properties, electrical and thermal conductivities and damping capacity over a wide temperature range are fabricated based on a well-developed master batch process. It is demonstrated that the MWCNTs are dispersed homogeneously due to the disentanglement induced by well-wetting and shearing, and the elastic-resilience-induced dispersion of the MWCNTs by rubber chains via the novel processing method. To further enhance the efficacy of elastic-resilience-induced dispersion for MWCNTs, a slightly pre-crosslinked network is constructed in the master batch. Consequently, we obtain rubber/MWCNT composites with unprecedented performance by amplifying the reinforcing effect of relatively low MWCNT loading. This work provides a novel insight into the fabrication of high performance functional elastomeric composites with pristine CNTs by taking advantage of the unique elastic resilience of rubber chains as the driving force for the disentanglement of CNTs.

In a rubber/filler composite, the surface chemistry of the filler is a critical factor in determining the properties of the composite because it affects the dispersion of the filler and the interfacial adhesion between the filler and rubber. In this study, we primarily focus on how graphene surface chemistry affects the dispersion of graphene and interfacial adhesion in butadiene–styrene rubber (SBR)/graphene composites and on the resultant properties of the composites. Composites that contain graphene with tailored surface chemistry are prepared via the chemical reduction of graphene oxide (GO) in situ. Subsequently, the dispersion of the graphene and interfacial adhesion are fully investigated in relation to the graphene surface chemistry. As revealed by dielectric relaxation spectroscopy, the bulk segmental relaxation is independent of the graphene surface chemistry, whereas the interfacial relaxation mode is retarded in the composite with stronger graphene–rubber affinity. The contribution of the graphene surface chemistry to the dispersion of the graphene and interfacial adhesion is quantified by calculating the surface energies. The results indicate that, when the COx fraction in the graphene is greater than 0.2, it exerts an increasingly strong effect on the dispersion of the graphene; in contrast, when the COx fraction is less than 0.2, it exerts a significant and positive effect on the interfacial interaction. In particular, on the basis of the surface energy analysis, quantitative predictors for the dispersion of graphene and interfacial adhesion are presented; these predictors can be used for the virtual design of graphene surface chemistry to optimize the properties of composites.

Sulphur-cured diene-based rubbers generally suffer from insufficient anti-ageing properties, and the curing process involves the use of toxic additives. Renewable conjugated acids are demonstrated to effectively cure epoxidized natural rubber into a high-performance elastomer, without the use of any toxic accelerators or antioxidants.