Pierre Sarazin

AN Esquirol (1st author), N Virgilio (Corresponding author).

Hydrogels embedded with networks of fully interconnected pores were prepared with microporous polylactide (PLA) molds obtained by extracting the polystyrene (PS) phase in melt-processed cocontinuous blends of PLA and PS. Quiescent annealing of the blends prior to the PS extraction allowed control over the average pore diameter from 1 to 500 μm for the PLA molds. Solutions of agar or alginate were injected within the molds and… Show more

AN Esquirol (1st author), N Virgilio (Corresponding author).

Hydrogels embedded with networks of fully interconnected pores were prepared with microporous polylactide (PLA) molds obtained by extracting the polystyrene (PS) phase in melt-processed cocontinuous blends of PLA and PS. Quiescent annealing of the blends prior to the PS extraction allowed control over the average pore diameter from 1 to 500 μm for the PLA molds. Solutions of agar or alginate were injected within the molds and gelled in situ. Porous gels were obtained by extracting the PLA molds and X-ray microtomography was employed to characterize their microstructure. Water removal/uptake cycles were fully reversible with very fast kinetics. Freeze-drying yielded ultraporous materials without modification of the macroscopic dimensions, and rehydration yielded back porous hydrogels. It was possible to scale up the technique by using extrusion and injection molding equipment. This versatile new method allows extensive control over the gels’ porosity parameters and the use of various gel chemistries. Show less

The activity of polystyrene-block-poly(l-lactide) (PS-b-PLLA) and polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) diblock copolymer brushes located at a PS/PLLA interface were employed as a route to control the final microstructure of 95% void volume, ultraporous PLLA scaffolds.

Ultraporous poly(l-lactide) (PLLA) scaffolds were prepared by melt-processing quaternary ethylene propylene diene rubber/poly(ε-caprolactone)/polystyrene/poly(l-lactide) (EPDM/PCL/PS/PLLA) 45/45/5/5 %vol. polymer blends modified with a PS-b-PLLA diblock copolymer. The morphology consists of a PS + PLLA+copolymer sub-blend layer forming at the interface of the EPDM and PCL phases. Quiescent annealing and interfacial modification using the block copolymer are used to control the blend… Show more

Ultraporous poly(l-lactide) (PLLA) scaffolds were prepared by melt-processing quaternary ethylene propylene diene rubber/poly(ε-caprolactone)/polystyrene/poly(l-lactide) (EPDM/PCL/PS/PLLA) 45/45/5/5 %vol. polymer blends modified with a PS-b-PLLA diblock copolymer. The morphology consists of a PS + PLLA+copolymer sub-blend layer forming at the interface of the EPDM and PCL phases. Quiescent annealing and interfacial modification using the block copolymer are used to control the blend microstructure. The ultraporous structure is subsequently obtained by selectively extracting the EPDM, PS and PCL phases. The PLLA scaffolds modified with the PS-b-PLLA copolymer present themselves as fully interconnected porous networks with asymmetric channel walls, one side being smooth while the other is covered with an array of submicron-sized PLLA droplets. They are prepared with a high degree of control over the pore size, with averages ranging from 5 μm to over 100 μm and a specific surface from 9.1 to 23.1 m2/g of PLLA, as annealing is carried out from 0 to 60 min. The void volume reaches values as high as 95% and in all cases the shape and dimensions of the scaffolds are maintained with a high level of integrity. The proposed method represents a comprehensive approach towards the design and generation of porous PLLA scaffolds based on complex morphologies from melt-processed multiphase polymer systems. Show less