Properties of Poly(dimethylsiloxane) Networks Prepared in Solution, and Their Use in Evaluating the Theories of Rubberlike Elasticity

Tough biodegradable mixed-macromer networks and hydrogels by photo-crosslinking in solution

The preparation of polymeric networks that are both tough and biodegradable remains a challenge. Here we show a very straightforward method to produce tough biodegradable networks from low molecular weight macromers for applications such as tissue engineering. Photo-crosslinking combinatorial mixtures of methacrylate-functionalized poly(1,3-trimethylene carbonate) (PTMC), poly(d,l-lactide) (PDLLA), poly(ε-caprolactone) (PCL) and poly(ethylene glycol) (PEG) oligomers in propylene carbonate (PC) allowed the preparation of network films with excellent tensile characteristics and resistance to tearing. This method enabled the production of both very tough mixed-macromer elastomers as well as mixed-macromer hydrogels. A mixed-macromer hydrogel prepared from 33wt.% PTMC, 33wt.% PCL and 33wt.% PEG had a very high tearing energy of 0.81kJ/m(2), which is comparable to tearing energies determined for articular cartilage.

Supercoiling transformation of chemical gels

The swelling/deswelling behavior of chemical gels has been an unsolved problem disputed over for a long time. The Obukhov-Rubinstein-Colby model depicts the influence that swelling/deswelling has on elasticity, but its physical picture is too complicated to be sufficiently validated by experiment. In this study, we use molecular dynamics simulation to verify the validity of the molecular picture of network strands predicted by the Obukhov-Rubinstein-Colby model. We conclude that the physical picture of the Obukhov-Rubinstein-Colby model is reasonable, and furthermore the simulation can reveal the details of conformational changes in network strands during the supercoiling transformation. Our findings not only reveal the validity, but also give a better understanding of the dynamics of the swelling/deswelling behavior of chemical gels.