Abstract
Porous polymers are receiving considerable attention in various disciplines such as energy, biomedical domains, or the environment. Their structure-property relationship must be perfectly mastered and defined in order to achieve the performances required in these fields of application. However, very few techniques allow an achievement of such structures in a controlled and reproductible manner. The block copolymer phase-separation represents a serious asset in this perspective, with its ability to generate nanoscale pores by a sacrificial block approach. Nevertheless, the phase-separation of biodegradable block copolymers remains under-researched, and it represents one of the key points of this study. In addition, responding to the need of developing non-toxic materials with low environmental impact, the use of biodegradable structures is a major requirement of the modern polymer science. Therefore, the objective of this PhD thesis is to develop biodegradable porous materials based on precisely selected block copolymer associations: one amorphous (PTMC-b-PDLLA-b-PTMC) and the other semi-crystalline (PTMC-b-PCL-b-PTMC), where both present an interaction parameter (χN) suitable for phase separation.Since the perfect control and the purity of the block copolymer architectures are being crucial for an efficient phase separation, the initial part of the study was devoted to a controlled ring-opening polymerization of these block copolymers while employing modern organocatalytic routes. In a second part, an in-depth theoretical and experimental study of the amorphous system self-assembly led to separate PTMC and PDLLA domains in bicontinuous nanophases. Selective hydrolysis of the PDLLA block resulted in nanometer-size porous PTMC matrix in the form of a thin film produced by the spin-coating technique. An additional step of photocrosslinking of the methacrylate end-chain groups allowed a mechanical reinforcement of the porous matrix. It is precisely the photocrosslinking step, combined with rapid liquid nitrogen quenching, that enabled a suppression of crystallinity and further access to a thermodynamical phase separation in the semi-crystalline system. In addition, the coexistence of both crystalline and crosslinked networks in the same structure, has allowed the establishment of advanced shape memory properties in these PTMC / PCL block copolymers. The last part of the study was devoted to the use of cleavable junctions in the aim to anticipate the slow degradability of the PCL phase. Hence, a cleavage of disulfides, initially located in the middle of the central PCL block, led to materials with interesting physicochemical properties.