Isabella Peroni

Self-repairing systems based on ionomers and epoxidized natural rubber blends.

The development of materials with the ability of intrinsic self-repairing after damage in a fashion resembling that of living tissues has important scientific and technological implications, particularly in relation to cost-effective approaches toward damage management of materials. Natural rubbers with epoxy functional groups in the macromolecular chain (ENR) and ethylene-methacrylic acid ionomers having acid groups partially neutralized with metal ions possess self-repairing behavior following high energy impacts. This research investigates the self-repairing behavior of both ENR and ionomers during ballistic puncture test on the basis of their thermal and mechanical properties. Heterogeneous blending of ionomers and ENR have also been used here as a strategy to tune the thermal and mechanical properties of the materials. Interestingly, blends of sodium ion containing ionomer exhibit complete self-repairing behavior, whereas blends of zinc ion containing ionomer show limited mending. The chemical structure studied by FTIR and thermal analysis shows that both ion content of ionomer and functionality of ENR have significant influence on the self-repairing behavior of blends. The mobility of rubbery phases along with its interaction to ionomer phase in the blends significantly changes the mending capability of materials. The healing behavior of the materials has been discussed on the basis of their thermal, mechanical, and rheological tests for each materials.

Pharmacokinetic results on naproxen prodrugs based on poly(ethyleneglycol)s

Five prodrugs of S(+)-2-(6-methoxy-2-naphthyl)propionic acid (naproxen), in which the drug was bound by ester linkages to diethyleneglycol (I), triethyleneglycol (II), octanediol (III), butyl-triethyleneglycol (IV), and butyl-tetraethyleneglycol (V), respectively, were prepared and tested for their pharmacokinetic properties after oral administration. It was found that bioavailabilities decreased in the order, and in all cases were lower than that of the free drug.

Synthesis and pharmacokinetic behaviour of ester derivatives of 4-isobutylphenyl-2-propionic acid (Ibuprofen) with end-hydroxylated poly(N-vinyl pyrrolidinone) and poly(N-acryloyl morpholine) oligomers

Four derivatives of 4-isobutylphenyl-2-propionic acid (Ibuprofen), in which the drug was bound by ester linkages to poly(ethylene glycols) (PEG 2000-I), monomethoxy poly(ethylene glycols) (PEG 1900-I), poly(N-vinyl pyrrolidinone) (PVP-I) and poly(N-acryloyl morpholine) (PACM-I), all having approximatively the same number average molecular weight (Mn congruent equal to 2000), were prepared and tested for their pharmacokinetic properties after oral administration. It was found that the two end-hydroxylated amphiphilic oligomers of polyvinylic structure, PACM and PVP, whose physico-chemical properties are comparable to those of PEGs especially as regards solvent affinity, have in principle a similar potential as promoieties for preparing oligomeric prodrugs.

Autonomous healing materials based on epoxidized natural rubber and ethylene methacrylic acid ionomers

The development of autonomous healing material has an enormous scientific and technological interest. In this context, this research work deals with the investigation of autonomous healing behavior of epoxidized natural rubber (ENR) and its blends with ethylene methacrylic acid ionomers. The autonomous healing behavior of ENR and its blends containing two different ionomers [poly(ethylene-co-methacrylic acid sodium salt) (EMNa) and poly(ethylene-co-methacrylic acid zinc salt) (EMZn)] has been studied by ballistic puncture tests. Interestingly, EMNa/ENR blends exhibit complete healing just after the ballistic test but EMZn/ENR blends do not show full self-repairing. The healing efficiency has been evaluated by optical microscopy and a depressurized air-flow test. The healing mechanism has been investigated by characterizing thermal and mechanical properties of the blends. The chemical structure studied by FTIR and thermal analysis show that the ion content of ionomers and functionality of ENR has a significant influence on the self-healing behavior.

Macroporous hydrogels with tailored morphology and mechanical properties

In this work it is shown that hydroxyethylcellulose (HEC) can be employed for preparing macroporous polyacrylamide (PAAm) hydrogels with tailored morphology and mechanical properties. By changing the HEC content in the reaction mixture hydrogels with different pore sizes and degrees of interconnectivity can be synthesized. The equilibrium swelling ratio in 0.1 M NaCl increases with the amount of HEC employed. Tensile tests run on equilibrated hydrogels show that these materials behave as rubber-like materials. Their mechanical stiffness decreases regularly as the amount of HEC, and therefore their porosity, is increased. A more complex trend is observed for elongation and stress at break, which display a maximum at intermediate contents of HEC.

Damage initiated self-healing in ionomer blends

The development and understanding of self-healing mechanisms have been investigated in blends of ionomers (Poly(ethyelene-co-methacrylic acid), sodium & zinc ions) (EMNa & EMZn) containing both elastomers (Epoxidized natural rubbers (ENR) and cis-1,4-Polyisoprene (PISP)) and crystalline component (Poly(vinly alcohol-co-ethylene) [PVAcE]) as secondary phases. All the blends were prepared by melt-blending and self-healing behavior was studied in ballistic puncture tests. Self-healing behavior of each material was evaluated by observing the impact zones under a stereo-optical microscope and the micrographic results were further supported by the fluid flow test in the punctured zones. Interestingly, ENR50 blends of sodium ion containing ionomers exhibited complete self-repairing behavior while zinc ion containing ionomer showed limited mending but EMNa/ENR25 and EMNa/PISP blends did not show any self-healing behavior following the damage. On the other hand, a composition dependent healing behavior was observe...