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Molecularly designed materials based on macromolecules and organic dyes offer unique opportunities in connection with the possibility of preparing optically responsive 'smart' materials. Indeed macromolecules are able to transmit and amplify small signals reaching sites at interacting distance through the involvement of the whole chain. The corresponding materials can then acquire stimuli-responsive properties in relation to specific features connected to primary structure and conformation. As a first approach to benefit from the above features for preparing eco compatible smartmaterials, bio-related polypeptides, polysaccharides and polyesters can be used as the macromolecular partner in combination with a selected dye following different interaction methodologies. Two distinct routes were used to prepare optically responsive products from the above bio-related polymers, respectively based either on the covalent bonding to the original macromolecules of photochromic molecular species, such as azobenzene and spiropyran, or on the morphology-modulated dispersion of highly conjugated dyes in the polymer bulk. Examples related to the two different routes have been investigated in our laboratory and are presented and discussed also with reference to selected recent cases from the literature.

The free radical post reactor modification of polyolefins with polar groups is a very well known methodology to functionalize macromolecular frameworks. The presence of grafted functionalities makes the pristine completely apolar polyolefins more compatible/interactive with polar additives as for example inorganic fillers or pigments etc. Usually, the conventional "grafting from" process involves the use of functionalizing molecules which are attached to polyolefin macroradicals through double bonds substituted by polar groups (maleic anhydride). This process is characterized by a generally very high efficiency, but owing to the not controlled macroradical formation has to be considered not selective. Recently, two TEMPO derivatives, the 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (HO-TEMPO) and the 4-benzoyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl (BzO-TEMPO), were reported to be a very interesting functionalizing agents because their quick reaction with macroradicals, generated by a peroxide initiator, limits all side reactions due to the presence of an excess of free radicals as for example the cross-linking and/or degradation processes.

The grafting of polar monomers to polyolefin backbones carried out in the melt in the presence of peroxides is accompanied by a restructuring of the pristinemacromolecule architecture depending on reaction conditions and original polyolefin structure. In the case of polypropylene (PP), side reactions, mainly degradation, are often controlled by the use of coagents which also provide amore complex scenario as far as possible reactions and final polymer structure are concerned.We have demonstrated that 2-furyl acrylates are very active inmaintaining the highmolecular weight of PP during various functionalization processes carried out in the melt in the presence of peroxides. In the study reported here, PP samplesmodified in themelt by free radical processes initiated with peroxides in the presence of butyl-3-(2-furyl) propenoate and its mixture with maleic anhydride were examined, and the effect of structural changes achieved were related to the rheology of themelt and morphological behaviour under heating. Rheological analysis is consistent with the formation of long branchedmacromolecules to an increasing extent with increasing content of reagents with respect to the polyolefin. Differential scanning calorimetry shows that the amount of long-chain branching is responsible for a decreaseof themelting temperatureandanincreaseof thecrystallization temperature. These results confirm that the functionalization coagent andmonomer can give large macromolecule structure changes which can be driven in different directions depending on feed composition

In the present contribution innovative methods to modify sodium mortmorillonite to obtain an organophilic filler are discussed and compared. The dispersion of this organoclays in the PLA matrix through a melt processing method is also discussed, by keeping into account structural, morphological and thermo -mechanical properties of the obtained composites. Moreover the ring opening polymerization onto rganoclay and dispersion of the polymerization product in a PLA matrix is investigated as an alternative route for the preparation of nanocomposites. Structural, morphological and thermo -mechanical properties of obtained composites were compared in order to assess advantages and disadvantages of the two different preparation procedures.

Polyolefin nanocomposites by varying the nature and structure of the polymer matrix (from EPM to PP), the type of polymer compatibilizer (grafted functionality and molecular weight) and the amount of layered silicate were prepared and characterized by XRD, TEM, DSC, TGA and dielectric measurements. The selective extraction of these materials was carried out to remove the nonbonded polymer and to isolate the composite with the sole polymer strongly interacting with the inorganic surface that was accurately characterized with respect, in particular, to morphology development and thermal characteristics. All the collected results were discussed by considering the role of interface between functionalized polyolefin chains and silicate layers and also in relation to resulting organoclay dispersion state and stability.

The functionalisation of a low molecular weight, liquid 1,2-polybutadiene (PBL) was performed by the addition of either N-acetyl-L-cysteine or its methyl ester through the thiol-ene radical reaction. The functionalisation runs were carried out in 1,4-dioxane solution and in the presence of a free radical initiator (2,20-azobisisobutyrronitrile, AIBN). The initial feed ratio polymer/cysteine derivative/initiator was varied, in order to highlight the occurrence of side reactions and to understand their possible influence on the process. The 1H NMR determination of the functionalisation degree brought out high addition degrees of thiols, regardless of the initial thiol/double bonds ratio. This caused a drastic change in the macroscopic properties of the PBL with improved solubility in hydrophilic solvents (for instance in alkaline aqueous solutions) and impressive increase of the glass transition temperature. The propagation of chiral properties from the functionalising agents to the modified polymers was evaluated by polarimetry and circular dichroism in solution.

Boehmite nanoparticles covered with a polymer shell enhancing the organophilicity of the surface were prepared by physical adsorption of a polyelectrolyte atom transfer radical polymerization (ATRP) macroinitiator followed by graft-polymerization of methyl methacrylate or 2-hydroxyethyl methacrylate. The presence of polymer chains adsorbed/grafted on the Boehmite was confirmed by attenuated total reflection infrared (ATR-IR) spectroscopy and by thermo-gravimetric analysis (TGA), which showed a significant amount of polymer covering the particles. The methodology of polymerization and the kinetics suggested the possibility to modulate the amount, type and thickness of grafted polymer shell. These organic-inorganic hybrid materials were melt compounded in a Brabender mixer with isotactic polypropylene in the presence of functionalized polypropylene. The dispersion degree of Boehmite nanoparticles in the polypropylene matrix as well as their reinforcing effect were studied by morphology characterization [scanning electron microscopy (SEM) and X-ray diffraction (XRD)], whereas thermal and thermo-mechanical properties were assessed by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA).

PP based layered silicates nanocomposites (PP-LSN) were prepared, by melt intercalation technique, by using PP grafted with maleic anhydride (PP-g-MAH) as coupling agent. The effect of MW and FD values of different PP-g-MAH samples on clay dispersion was investigated. These PP-g-MAH samples were obtained by using butyl 3-(2-furyl) propenoate (BFA) as coagent during the radical functionalization of PP with MAH in order to avoid the polymer degradation. The obtained materials, differing from FD and MW were employed as polymer matrices for the preparation of nanocomposites. Successively, PP-LSN were prepared by using PP as matrix and 5 phr of the above high MW compatibilizers. Morphological, thermal, mechanical and thermo-mechanical analyses of the nanocomposites pointed out that the higher MW PP-g-MAH allows to achieve simultaneously a good intercalation within the filler and a significant compatibilization with neat PP chains, leading to high performance PP-LSN.