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The synthesis of polymers with controlled macromolecular architecture according to well tested models of chain growth is important from both academic and industrial points of view. Upon correlation of structure with properties in such polymers and by application of models developed in this work, new polymeric materials with optimized physical properties can be obtained. The present work reports the synthesis, according to the mentioned chain growth models of star, tree and star-tree PA11 and PLA, together with their melt and solid-state characterization.

Composites of a terpolymer (46mol% L-lactic acid, 38mol% glycolic acid, 16mol% trimethylene carbonate) and TiO2 nanoparticles (0-2w%) are obtained from sonicated dispersions in dichloromethane followed by solvent evaporation. All samples display a glass transition at a temperature close to body temperature; Tg of composites is slightly higher than that of the matrix polymer, indicating a degree of polymer-nanoparticle interaction. The addition of TiO2 nanoparticles improves the mechanical properties of the polymer (tensile modulus and tensile strength increase) and enhances both the free recovery (from 92% to 100% with 1.92w% of TiO2) and the constrained recovery in the presence of an opposing force (from 7% to 34 % with 1.92w% of TiO2).

Structural complexity inherited from a microbial synthesis of glycolipids was translated into unique poly(sophorolipid) biomaterials. ROMP polymn. of natural diacetylated lactonic sophorolipids gave a high mol. wt. polymer with asym. bola-amphiphilic repeating units. The poly(sophorolipid) chain alternates C18 oleic-like aliph. segments (90% cis-configured double bonds) with bulky diacetylated disaccharide moieties. The poly(sophorolipid) is a solid at room temp. that undergoes the glass transition at 61 °C and melts at 123 °C. The crystal phase is assocd. with ordered packing of the aliph. chain segments. The semicryst. poly(sophorolipid) also displays a long-range order (d = 2.44 nm) involving sophorose groups that persist after crystal phase melting (in high-T diffractograms) with a slightly shortened distance (2.27 nm).

Bioresorbable new terpolymers of L-lactide, glycolide and trimethylene carbonate with different composition were synthesized via ring opening polymerization reaction of the cyclic monomers using low-toxicity zirconium (IV) acetylacetonate as initiator. The thermal and mechanical properties were investigated by means of thermogravimetry, differential scanning calorimetry, stress-strain measurements and dynamical mechanical analysis. The glass transition temperature of the terpolymers changes with composition from 12°C to 42°C in a predictable manner. All terpolymers display shape memory properties and, after undergoing 100% deformation, they recover the permanent shape in a time frame of seconds. Terpolymers with high L-lactide content show a glass transition in the range 38-42°C, recovery temperature close to body temperature and good recovery ratio (> 0.89). Low toxicity bioresorbable terpolymers with shape memory properties are promising new materials for biomedical applications

Terpolymers of L-lactide, glycolide and trimethylene carbonate are synthesized via ring opening polymerization reaction of the cyclic monomers using zirconium acetylacetonate as initiator. All terpolymers are amorphous single phase materials with a glass transition temperature (Tg) that changes with composition. Thermomechanical experiments show that the polymers display shape memory properties and that they are able to recover the original shape in a matter of seconds after a suitable thermal stimulus. Thanks to the possibility to modulate the Tg by varying the monomer feed ratio, shape memory polymers with selected transition temperature can be obtained for specific applications.

Polyamide 11 (PA11) is a bio-based technopolymer synthesized using 11-aminoundecanoic acid from castor oil. In this work star-shaped PA11 structures are obtained via one-pot copolycondensation of 11-aminoundecanoic acid with a multifunctional agent, either 3-functional bis hexamethylentriamine or tetra-functional 2,2,6,6-tetra[β-carboxyethylcyclohexanone]. A theoretical model predicting the macromolecular complexity of the star shaped polycondensates that result from the reaction is used to interpret the rheological behavior of the synthesized samples, that is found to be strongly affected by the presence of branching. It is shown that melt properties can be modulated, for easier processability, by simply controlling monomer feed ratio and conversion of the copolycondensation reaction. In the range of comonomer functionality and content explored, thermal properties do not significantly vary with changing macromolecular architecture. All star-shaped polyamide samples easily crystallize and their structural characterization above room temperature shows that upon heating they reversibly undergo the alpha-gamma crystal phase transition that is typical of linear PA11. Investigation of the effect of branching on the mechanical properties shows that careful selection of chain controller type and amount allows to obtain star-shaped PA11 samples with ad-hoc modulated melt viscosity and preserved material’s mechanical performance.