Terpenes-based (meth)acrylic polymers as new class of functional materials

Resumen

This PhD thesis aims at contributing to the reduction of the petroleum dependence by producing polymers using monomer obtained from bio-sourced terpenes. The terpenes are side products of the local paper industry created around the ¿Landes¿ pine forest in the South West of France. Tetrahydrogeraniol (THG) and Cyclademol (CDM) were chosen as terpene derivatives to prepare (meth)acrylic monomers that can replace its petroleum-based homologues n-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate and styrene. A synthetic method for the efficient production of several terpene-containing (meth)acrylates (tetrahydrogeraniol acrylate (THGA), tetrahydroheranoiol methacrylate (THGMA), cyclademol acrylate (CDMA) and cyclademol methacrylate (CDMMA)) was developed. These monomers were polymerized in bulk, solution and aqueous dispersed systems by free radical polymerization, RAFT polymerization and nitroxide mediated polymerization (NMP). THGA was first polymerized in toluene and bulk via free-radical polymerization, achieving high conversions and molecular weights with good control. However, the synthetic route used is not sustainable as the polymerizations were carried out in solution, namely with an extensive use of solvent. The seek for a more sustainable synthetic method prompted us to polymerize the new monomers in aqueous dispersed media, which is more environmentally friendly. Good control over the RAFT polymerization was achieved, an stable dispersions of poly(THGA) with degrees of polymerization ranging from 50 to 450, relatively low polydispersity values and high conversions were obtained. Both hard-soft-hard and soft-hard-soft triblock copolymers were prepared using poly(THGA) as soft segment and poly(CDMMA) as hard one. The nano-phase segregation of the copolymers was observed by AFM and rheological measurements. Finally, the formulations using fully bio-based monomers shown good adhesive performance, in comparison to triblock copolymers partially based on styrene. Block copolymers from bio-sourced terpene-based methacrylates were also successfully synthesized by nitroxide mediated polymerization using the alkoxyamine Dispolreg 007. The process was carried out in miniemulsion, excellent control over the polymerization of THGMA could be achieved up to DPn 500 and narrow molecular weight distributions at high conversion were obtained. Terpene-based soft/hard diblock copolymers were successfully synthesized starting with a THGMA macroradical, varying the molecular weight of hard polymer (CDMMA). The adhesive properties of the diblock copolymers were evaluated with probe tack, peel strength and shear resistance measurements. The adhesive performance was comparable to the partially petroleum-based styrene system and better than that found for the acrylate-based triblock copolymers.