In this study, we were particularly interested in looking at the possibility that cross metathesis of olefins in melt phase could be used to produce polydimethylsiloxane (PDMS) modified polypropylene (PP). The intention of this project was also to study and quantify relationships among the main experimental factors in the reaction: temperature, catalyst concentration and molar ratio of PP to PDMS, through a 2-level factorial statistical design. In order to examine if PP-PDMS copolymers were synthesized in the melt phase, measurement of the chemical, physical and viscoelastic properties of the synthesized copolymers was necessary. Techniques including proton (¹H)-nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), rheometry and scanning electron microscopy (SEM), were all used to characterize the synthesized copolymers. ¹H NMR measurements confirmed the presence of PDMS in the copolymers. They also provided a quantitative measurement of PP to PDMS molar ratio in copolymers by determining the integration of PP PDMS repeating unit signals in NMR spectra. Compared to virgin PP, a lower melting enthalpy of the PP phase in the copolymer was observed from DSC results. This implied that the PDMS component influenced the thermal behavior of the PP crystalline phase in the copolymers. Moreover, TGA measurements indicated that a higher thermal stability was obtained for PP-PDMS copolymers than that for virgin PP wax and this was expected since PDMS is known for its excellent stability at high temperature. Rheological analysis showed that the presence of PDMS in the copolymers gave lower complex viscosities and loss moduli, but higher storage moduli than those for virgin PP. Furthermore, the morphology of copolymers was examined by SEM and elemental analysis at the surface using an energy dispersive X-ray (EDX) analyzer on the SEM. It was found that micrographs of copolymers showed round domains on the surface, which were not observed in virgin PP wax and those round segments were confirmed to contain silicon. Torque values used in a batch mixer for polymerizations and the remaining weight % of copolymers at 350°C were used to conduct statistical analysis, through which models used to describe the relationships between experimental factors and these physical responses were determined.

In this study, we were particularly interested in looking at the possibility that cross metathesis of olefins in melt phase could be used to produce polydimethylsiloxane (PDMS) modified polypropylene (PP). The intention of this project was also to study and quantify relationships among the main experimental factors in the reaction: temperature, catalyst concentration and molar ratio of PP to PDMS, through a 2-level factorial statistical design. In order to examine if PP-PDMS copolymers were synthesized in the melt phase, measurement of the chemical, physical and viscoelastic properties of the synthesized copolymers was necessary. Techniques including proton (¹H)-nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), rheometry and scanning electron microscopy (SEM), were all used to characterize the synthesized copolymers. ¹H NMR measurements confirmed the presence of PDMS in the copolymers. They also provided a quantitative measurement of PP to PDMS molar ratio in copolymers by determining the integration of PP PDMS repeating unit signals in NMR spectra. Compared to virgin PP, a lower melting enthalpy of the PP phase in the copolymer was observed from DSC results. This implied that the PDMS component influenced the thermal behavior of the PP crystalline phase in the copolymers. Moreover, TGA measurements indicated that a higher thermal stability was obtained for PP-PDMS copolymers than that for virgin PP wax and this was expected since PDMS is known for its excellent stability at high temperature. Rheological analysis showed that the presence of PDMS in the copolymers gave lower complex viscosities and loss moduli, but higher storage moduli than those for virgin PP. Furthermore, the morphology of copolymers was examined by SEM and elemental analysis at the surface using an energy dispersive X-ray (EDX) analyzer on the SEM. It was found that micrographs of copolymers showed round domains on the surface, which were not observed in virgin PP wax and those round segments were confirmed to contain silicon. Torque values used in a batch mixer for polymerizations and the remaining weight % of copolymers at 350°C were used to conduct statistical analysis, through which models used to describe the relationships between experimental factors and these physical responses were determined.

Knowledge of radical initiated grafting was summarized in theoretical part. It also contains a part about adamantane, its derivatives and a study of their use in polymer chemistry. In experimental part radical grafted polypropylene was prepared in batch mixer Brabender at 185 and 195 °C, 40 RPM and reaction time 5 min. Initiator 2,5-dimethyl-2,5-bis(tert-buthylperoxy)hexane (Trigonox 101) in concentrations between 0,2 – 4 wt % was used. 1-vinyladamantane was chosen as a monomer and its concetration ranged from 0,75 to 2,24 wt %. Mechanical properties of prepared samples were tested. Sample with content of initiator 0,2 wt % and monomer 1,4 wt % showed increase in notch toughness by 56,3 %, strength by 8,7 %, ductility by 11,5 % and decrease in MFR (230 °C; 2,16 kg) by 29,7 %. Values of torque indicated grafting reactions which couldn’t be proven by use of FTIR method so more suitable methods have been proposed.

This thesis deals with a preparation of modified polypropylene. Modified polypropylene was prepared by reaction itaconic anhydride and compounds contain primary and secondary amino group (diaminododecane, aminoethylethanolamine and aminoethylpiperazine). Knowledge of radical and condensation modification of polypropylene were summarized in the theoretical part. New application of modified polypropylene ware summarized at the theoretical part as well. In the experimental part polypropylene was functionalized by grafting with itaconic anhydride during reactive extrusion. Extrusion was carried on the co-rotating twin-screw extruder (Brabender 25 DSE L/D = 34) at 230 °C and 30 RPM. Residence time of reactive blend was 3 minutes. The modified polypropylene PP-g-IAH) contained 0.5 wt% of itaconic anhydride. 2,5 dimethyl 2,5bis(tert buthyl-peroxy)hexane (Luperox 101) was used as a radical initiator. A ratio initiator/monomer was 1:0.6 (mol/mol). PP-g-IAH was used for condensation reaction with amino compounds in molar ratios IAH/amine from 1:0,3 to 1:1. This reaction carried out in single screw extruder (Betol 1825 L/D = 39) at 210 °C and 30 RPM. Residence time of reactive blend was 3 minutes. Fourier transform infrared spectroscopy was used for a calculation of reaction conversion and for description of new functional groups in the materials. This analysis confirmed the presence of amide and imide groups in the samples. Influence of amino compounds to polymer crystallinity was studied by differential scanning calorimetry. Termogravimetric analysis focused on thermal stability of prepared samples and changes of thermal stability was observed in dependence of additives amount. The rheological behaviors of modified PP were analyzed by measuring the complex viscosity.

The delivery of small interfering RNAs (siRNA) is an efficient method for gene silencing through the induction of RNA interference (RNAi). It critically relies, however, on efficient vehicles for siRNA formulation, for transfection in vitro as well as for their potential use in vivo. While polyethylenimines (PEIs) are among the most studied cationic polymers for nucleic acid delivery including small RNA molecules, polypropylenimines (PPIs) have been explored to a lesser extent. Previous studies have shown the benefit of the modification of small PEIs by tyrosine grafting which are featured in this paper. Additionally, we have now extended this approach towards PPIs, presenting tyrosine-modified PPIs (named PPI-Y) for the first time. In this study, we describe the marked improvement of PPI upon its tyrosine modification, leading to enhanced siRNA complexation, complex stability, siRNA delivery, knockdown efficacy and biocompatibility. Results of PPI-Y/siRNA complexes are also compared with data based on tyrosine-modified linear or branched PEIs (LPxY or PxY). Taken together, this establishes tyrosine-modified PPIs or PEIs as particularly promising polymeric systems for siRNA formulation and delivery.