Monika Makrocka-Rydzyk | Adam Mickiewicz University in Poznań (original) (raw)

Papers by Monika Makrocka-Rydzyk

Langmuir, 2017

Two polystyrene-b-poly(ethylene oxide) (PS-b-PEO) diblock copolymers differing in molecular mass ... more Two polystyrene-b-poly(ethylene oxide) (PS-b-PEO) diblock copolymers differing in molecular mass (49 and 78 kDa), but possessing the same PEO cylindrical morphology, are examined to elucidate their molecular dynamics. Of particular interest here is the molecular motion of the PEO blocks involved in the rigid amorphous fraction (RAF). Analysis of complementary thermal calorimetry and X-ray scattering data confirm the presence of a microphase-separated morphology, as well as semi-crystalline structure, in each copolymer. Molecular motion within the copolymer systems is monitored by dielectric and nuclear magnetic resonance spectroscopies. Results reported herein reveal the existence of two local, Arrhenius-type processes attributed to non-cooperative local motion of PEO segments involved in fully amorphous and rigid amorphous PEO microphases. In both systems, two structural relaxations governed by glass transition phenomena are identified and assigned to cooperative segmental motion in the fully amorphous phase (the α process) and the RAF (the α c process). We measure the temperature dependence of the dynamics associated with all the processes mentioned above and propose that these local processes are associated with corresponding cooperative segmental motion in both copolymer systems. In marked contrast to the thermal activation of the α process as discerned in both copolymers, the α c process appears to be a sensitive probe of the copolymer nanostructure. That is, the copolymer with shorter PEO blocks exhibits more highly restricted cooperative dynamics of PEO segments in the RAF, which can be explained in terms of the greater constraint imposed by the glassy PS matrix on the PEO blocks comprising smaller cylindrical microdomains.

Advances in molecular medicine related to the treatment of genetic disorders and cancer require f... more Advances in molecular medicine related to the treatment of genetic disorders and cancer require finding new pathways for gene transfer. Nonviral delivery methods rely on the application of polymers, liposomes and cationic lipid systems used as vehicle. Among these systems, there is increasing interest in surfactants, which, due to their ability to complex with nucleic acids can deliver into cell DNA or RNA molecules of almost any size, which is unattainable with viral gene delivery systems.The main aim of this study was to determine the effect of the concentration of lactose-based surfactants (zwitterionic derivatives of sulfobetaine with carbohydrate moieties) on the structure of DNA/RNA as well as to explore their abilities of nucleic acid complexation. Structural studies of DNA or RNA in complexes with surfactants of two types at various concentrations were conducted using circular dichroism (CD) spectroscopy, gel electrophoresis (GE) and synchrotron radiation small angle X-ray s...

Polymer, 2013

ABSTRACT Molecular dynamics of miktoarm star copolymers consisting of poly(n-butyl acrylate) PBA ... more ABSTRACT Molecular dynamics of miktoarm star copolymers consisting of poly(n-butyl acrylate) PBA and polyethylene oxide (PEO) arms was studied by means of Broadband Dielectric Spectroscopy (BDS) and Nuclear Magnetic Resonance (NMR) methods. The spectroscopic studies were performed for three types of copolymers differing in the composition, namely materials containing 76%, 46% and 16% molar fraction of PBA arms. The local processes, described by the Arrhenius law (e.g. the anisotropic rotation of methyl groups and the anisotropic local motions in the PEO chain), were observed for the studied systems below the glass transition temperature. It was found that the investigated PBA/PEO miktoarm star copolymers are characterized by single glass transition, which may result from similar values of glass transition temperatures of the PBA and PEO polymers. The segmental dynamics in the studied systems was quantitatively described by using the Vogel-Fulcher-Tammann (VFT) relation applied to combined NMR and BDS data. Moreover, above the glass transition temperature the interfacial polarization and conductivity phenomena were detected with the BDS method for all systems under study.

Zeitschrift für Physikalische Chemie, 2012

ABSTRACT Morphology and NMR self-diffusion of two miktoarm star copolymers differing in fraction ... more ABSTRACT Morphology and NMR self-diffusion of two miktoarm star copolymers differing in fraction of poly(n-butyl acrylate) and poly(ethylene oxide) (PBA and PEO) arms were under investigation. Structural characteristics of copolymers was obtained on the basis of Small Angle X-Ray Scattering (SAXS) investigations. The phase separated nanoscale morphology of the miktoarm star copolymer with a high fraction of PEO arms was confirmed by Scanning Probe Microscopy (SPM) studies. The modified Avrami approach was used to obtain the information on the non-isothermal crystallization kinetics of the studied systems. It was observed that the crystallization in the system with a higher content of PBA, occurring at higher undercooling, was characterized by a higher crystallization rate. It was also found that increase in PBA arms fraction leads to the reduction in the size of PEO domains. The activation energy of the crystallization process, estimated with Kissinger's method, is lower for miktoarm star copolymer with higher PBA content, which results from facilitation of the transport of PEO chains in the direction of the growing crystal due to the presence of mobile PBA arms. The self-diffusion studies of miktoarm star copolymers melts, carried out with the Pulsed-Gradient STimulated-Echo (PGSTE) Nuclear Magnetic Resonance (NMR) technique, reveals the existence of at least two types of diffusion mechanisms in these systems.

Journal of Non-Crystalline Solids, 2010

Acta Physica Polonica A, 2005

Nuclear magnetic resonance, broadband dielectric spectroscopy and dynamic-mechanical thermal anal... more Nuclear magnetic resonance, broadband dielectric spectroscopy and dynamic-mechanical thermal analysis were employed to study molecular dynamics of ethylene-norbornene copolymer. The analysis of experimental data indicates existence of three motional processes denoted as α, β, and γ in order of decreasing temperature. The α relaxation is related to the dynamic glass transition, while the β relaxation, observed only for the untreated sample, is assigned to short range segmental motions involving norbornene units. The γ relaxation is due to very local motions of ethylene units e.g. trans-gauche isomerization, similar to those responsible for γ relaxation in polyethylene. The rate of motion accountable for γ process, follows the Vogel-Fulcher-Tammann equation, similarly to α transition, indicating cooperative nature of the motion.

Solid State Nuclear Magnetic Resonance, 2015

Molecular motions in poly(ethylene-co-norbornene) were studied in a temperature range well below ... more Molecular motions in poly(ethylene-co-norbornene) were studied in a temperature range well below its glass transition point by a few techniques based on the NMR phenomenon. Temperature dependencies of proton spin-lattice relaxation times T1 (at 200MHz and at 30.2MHz), proton spin-lattice relaxation time in the rotating frame T1ρ (at 68kHz) and frequency dispersion of proton spin-lattice off-resonance relaxation times in the rotating frame T1ρ(off) were determined for the copolymer. Analysis of (1)H NMR relaxation data permitted characterization of local motions occurring in the copolymer i.e. rotation of methyl groups around C3 axes, reorientations of methylene groups and motions of segments of polymer chains including norbornene groups.

Synthetic Metals, 2015

In this work we report a reproducible and efficient method of surface modification of titania nan... more In this work we report a reproducible and efficient method of surface modification of titania nanoparticles (rutile) via reversible-deactivation radical polymerization. Herein, we graft poly(di (ethylene glycol) methyl ether methacrylate) from the surface of TiO 2 in an amount of 21 wt% within the reaction time of 3 h 15 min. The amount of grafted polymer was assessed by Thermogravimetric Analysis and it is one of the highest reported till now for this ceramic nanoparticles by atom transfer radical polymerization. The properties of inorganic-organic, i.e. core-shell material, as well as of pristine TiO 2 and neat polymer were examined by Infrared and Dielectric Spectroscopies. The shape of the nanoparticles and the thickness of the polymer coating shell were investigated by means of High Resolution Transmission Electron Microscopy. The obtained nanocomposite exhibits dielectric permittivity e 0 = 18 and loss tangent around 1 Â10 À2 at 20 C. The described method allows controlling a length and chemical structure of the grafted polymer from ceramic core, thus to tailor a physical properties of nanoparticles and of nanocomposites.

Solid State Nuclear Magnetic Resonance, 1995

dependences of proton and fluorine second moments and spin-lattice relaxation time T, below glass... more dependences of proton and fluorine second moments and spin-lattice relaxation time T, below glass transition were measured in glassy "I-Do,Pip-Me-BF," ionene. The existence of motions of methyl groups and segments linking the cationic centers, namely piperidinium rings and trimethylene groups, for the polymeric part of ionene were established. Isotropic rotation of the counter-ion was evidenced and its limited diffusion suggested. To interpret the proton and fluorine relaxation data, a Davidson-Cole distribution of correlation times was assumed. 0926-2040/95/$09.50 0 1995 Elsevier Science B.V. All rights reserved SSDI 0926.2040(95)00013-5

Polymer, 2010

Dynamic mechanical studies of molecular dynamics have been performed for two ethylene-norbornene ... more Dynamic mechanical studies of molecular dynamics have been performed for two ethylene-norbornene copolymers. The analysis of data indicates the existence of three relaxation processes: a primary (a) and two secondary (b and g) ones. It was found that the secondary processes b and g are connected with the local motions of ethylene and norbornene groups, respectively and that their rates follow the Arrhenius relation. Moreover, the b process was recognized as the Johari-Goldstein process acting as the precursor of the cooperative structural a-relaxation. Contrary to g and b processes, the motional rate of a-one follows the Vogel-Fulcher-Tammann equation indicating the cooperative nature of motions involved in this process. An increase in norbornene content in copolymer slows down the molecular dynamics of both norbornene fragments and whole chains, and in consequence shifts these relaxation processes into higher temperatures. Using the Havriliak-Negami formalism the motional parameters for the processes mentioned above were estimated.

Polymer, 2011

Structural behavior of miktoarm star polymers comprising poly(butyl acrylate) (PBA) and poly(ethy... more Structural behavior of miktoarm star polymers comprising poly(butyl acrylate) (PBA) and poly(ethylene oxide) (PEO) arms was studied by means of Differential Scanning Calorimetry (DSC), Wide Angle X-Ray Scattering (WAXS), Polarized Optical Microscopy (POM) and Fourier Transform Infrared Spectroscopy (FTIR) methods. The aim of this study was to correlate changes in the composition of the arms of the PBA/ PEO miktoarm star polymers with their structures. As a consequence of increasing PBA content, the decrease in crystallinity of the studied PBA/PEO heteroarm star copolymers was observed. Regardless of the copolymer composition, fraction of oxyethylene units in the crystalline PEO phase was similar in all investigated systems. The POM images showed spherulitic morphology of the materials having low PBA content, while an increase in PBA arms fraction leads to the formation of less ordered structures. The analysis of FTIR vibrational spectrum indicates helical conformation of PEO chains in the crystalline phase. Isothermal crystallization studies carried out using the FTIR technique suggest the existence of isolated domains in the nanoscopic scale of investigated materials.

Macromolecular Chemistry and Physics, 2007

Journal of Non-Crystalline Solids, 2010

Molecular dynamics of polyisoprene, polystyrene and poly(styrene-b-isoprene) diblock copolymer ha... more Molecular dynamics of polyisoprene, polystyrene and poly(styrene-b-isoprene) diblock copolymer has been studied by means of broadband dielectric and magnetic resonance spectroscopies. The measurements of dielectric permittivity as well as NMR second moment, spin-lattice relaxation times T 1 and T 1q in wide range of temperature were performed. It was found that the copolymer exhibits all motions observed in the neat components i.e., three motions connected with polyisoprene blocks (segmental, normal-mode and methyl group rotation) and one (segmental) related to polystyrene blocks. The mutual interaction between polystyrene and polyisoprene chains leads to stiffening of polyisoprene blocks and loosening of polystyrene structure. The polyisoprene segmental and normal-mode motions were analyzed in terms of the Havriliak-Negami model and Vogel-Fulcher-Tamman (VFT) relation. Based on NMR spin-diffusion experiment the size of polystyrene domains in copolymer was evaluated and accounts to 9 nm.

Journal of Non-Crystalline Solids, 2010

Rheological and dielectric behavior of linear PDMS and alkyl-modified PDMS melts has been studied... more Rheological and dielectric behavior of linear PDMS and alkyl-modified PDMS melts has been studied. Molecular dynamics of linear PDMS, being a model of grafted polydimethylsiloxanes studied, has been examined carefully with particular attention paid to its ability to form the semicrystalline phase. Random incorporation of alkyl groups into PDMS chain has been shown to prevent the polymer crystallization. The glass transition temperature of the grafted PDMS changes proportionally to the modifier content.

European Polymer Journal, 2002

1 H and 13 C NMR spectra and 1 H spin-lattice relaxation times T 1 and T 1q have been employed to... more 1 H and 13 C NMR spectra and 1 H spin-lattice relaxation times T 1 and T 1q have been employed to study the structure and molecular dynamics in polyethylene and ethylene-1-butene copolymer in the temperature range from 100 to 370 K. Results are interpreted in terms of a, b and c -relaxation, as well as methyl group rotation. The activation energies for all motions were established. The incorporation of 1-butene into ethylene chain leads to an increase of mobility in amorphous and crystalline phases as well as appearance the 13 C resonance characteristic to the monoclinic structure in addition to the orthorhombic observed in both polymers. The crystallinity degree derived from T 1q in studied polymers is close to that determined using DSC method. Ó

European Polymer Journal, 2013

The nuclear magnetic resonance (NMR) and dielectric spectroscopy (DS) methods were used to invest... more The nuclear magnetic resonance (NMR) and dielectric spectroscopy (DS) methods were used to investigate the segmental and global dynamics in lamellar microphase separated poly(styrene-b-isoprene) (SI) diblock copolymer. For the first time, the susceptibility representation of the NMR relaxation data is applied to the analysis of the molecular dynamics in complex polymer systems like the diblock copolymer. This approach in combination with the frequency-temperature superposition (FTS) allows one to compare directly the NMR and DS data in an extended frequency range providing a unique comprehensive picture of various relaxation processes present in the system studied. The findings of these investigations include structural relaxations of the polyisoprene (PI) and the polystyrene (PS) blocks, a normal mode relaxation of the PI block, and an extra low frequency interfacial relaxation. Special attention has been devoted to influence of the copolymer morphology on the segmental and global dynamics in PI.

Langmuir, 2017

Two polystyrene-b-poly(ethylene oxide) (PS-b-PEO) diblock copolymers differing in molecular mass ... more Two polystyrene-b-poly(ethylene oxide) (PS-b-PEO) diblock copolymers differing in molecular mass (49 and 78 kDa), but possessing the same PEO cylindrical morphology, are examined to elucidate their molecular dynamics. Of particular interest here is the molecular motion of the PEO blocks involved in the rigid amorphous fraction (RAF). Analysis of complementary thermal calorimetry and X-ray scattering data confirm the presence of a microphase-separated morphology, as well as semi-crystalline structure, in each copolymer. Molecular motion within the copolymer systems is monitored by dielectric and nuclear magnetic resonance spectroscopies. Results reported herein reveal the existence of two local, Arrhenius-type processes attributed to non-cooperative local motion of PEO segments involved in fully amorphous and rigid amorphous PEO microphases. In both systems, two structural relaxations governed by glass transition phenomena are identified and assigned to cooperative segmental motion in the fully amorphous phase (the α process) and the RAF (the α c process). We measure the temperature dependence of the dynamics associated with all the processes mentioned above and propose that these local processes are associated with corresponding cooperative segmental motion in both copolymer systems. In marked contrast to the thermal activation of the α process as discerned in both copolymers, the α c process appears to be a sensitive probe of the copolymer nanostructure. That is, the copolymer with shorter PEO blocks exhibits more highly restricted cooperative dynamics of PEO segments in the RAF, which can be explained in terms of the greater constraint imposed by the glassy PS matrix on the PEO blocks comprising smaller cylindrical microdomains.

Advances in molecular medicine related to the treatment of genetic disorders and cancer require f... more Advances in molecular medicine related to the treatment of genetic disorders and cancer require finding new pathways for gene transfer. Nonviral delivery methods rely on the application of polymers, liposomes and cationic lipid systems used as vehicle. Among these systems, there is increasing interest in surfactants, which, due to their ability to complex with nucleic acids can deliver into cell DNA or RNA molecules of almost any size, which is unattainable with viral gene delivery systems.The main aim of this study was to determine the effect of the concentration of lactose-based surfactants (zwitterionic derivatives of sulfobetaine with carbohydrate moieties) on the structure of DNA/RNA as well as to explore their abilities of nucleic acid complexation. Structural studies of DNA or RNA in complexes with surfactants of two types at various concentrations were conducted using circular dichroism (CD) spectroscopy, gel electrophoresis (GE) and synchrotron radiation small angle X-ray s...

Polymer, 2013

ABSTRACT Molecular dynamics of miktoarm star copolymers consisting of poly(n-butyl acrylate) PBA ... more ABSTRACT Molecular dynamics of miktoarm star copolymers consisting of poly(n-butyl acrylate) PBA and polyethylene oxide (PEO) arms was studied by means of Broadband Dielectric Spectroscopy (BDS) and Nuclear Magnetic Resonance (NMR) methods. The spectroscopic studies were performed for three types of copolymers differing in the composition, namely materials containing 76%, 46% and 16% molar fraction of PBA arms. The local processes, described by the Arrhenius law (e.g. the anisotropic rotation of methyl groups and the anisotropic local motions in the PEO chain), were observed for the studied systems below the glass transition temperature. It was found that the investigated PBA/PEO miktoarm star copolymers are characterized by single glass transition, which may result from similar values of glass transition temperatures of the PBA and PEO polymers. The segmental dynamics in the studied systems was quantitatively described by using the Vogel-Fulcher-Tammann (VFT) relation applied to combined NMR and BDS data. Moreover, above the glass transition temperature the interfacial polarization and conductivity phenomena were detected with the BDS method for all systems under study.

Zeitschrift für Physikalische Chemie, 2012

ABSTRACT Morphology and NMR self-diffusion of two miktoarm star copolymers differing in fraction ... more ABSTRACT Morphology and NMR self-diffusion of two miktoarm star copolymers differing in fraction of poly(n-butyl acrylate) and poly(ethylene oxide) (PBA and PEO) arms were under investigation. Structural characteristics of copolymers was obtained on the basis of Small Angle X-Ray Scattering (SAXS) investigations. The phase separated nanoscale morphology of the miktoarm star copolymer with a high fraction of PEO arms was confirmed by Scanning Probe Microscopy (SPM) studies. The modified Avrami approach was used to obtain the information on the non-isothermal crystallization kinetics of the studied systems. It was observed that the crystallization in the system with a higher content of PBA, occurring at higher undercooling, was characterized by a higher crystallization rate. It was also found that increase in PBA arms fraction leads to the reduction in the size of PEO domains. The activation energy of the crystallization process, estimated with Kissinger's method, is lower for miktoarm star copolymer with higher PBA content, which results from facilitation of the transport of PEO chains in the direction of the growing crystal due to the presence of mobile PBA arms. The self-diffusion studies of miktoarm star copolymers melts, carried out with the Pulsed-Gradient STimulated-Echo (PGSTE) Nuclear Magnetic Resonance (NMR) technique, reveals the existence of at least two types of diffusion mechanisms in these systems.

Journal of Non-Crystalline Solids, 2010

Acta Physica Polonica A, 2005

Nuclear magnetic resonance, broadband dielectric spectroscopy and dynamic-mechanical thermal anal... more Nuclear magnetic resonance, broadband dielectric spectroscopy and dynamic-mechanical thermal analysis were employed to study molecular dynamics of ethylene-norbornene copolymer. The analysis of experimental data indicates existence of three motional processes denoted as α, β, and γ in order of decreasing temperature. The α relaxation is related to the dynamic glass transition, while the β relaxation, observed only for the untreated sample, is assigned to short range segmental motions involving norbornene units. The γ relaxation is due to very local motions of ethylene units e.g. trans-gauche isomerization, similar to those responsible for γ relaxation in polyethylene. The rate of motion accountable for γ process, follows the Vogel-Fulcher-Tammann equation, similarly to α transition, indicating cooperative nature of the motion.

Solid State Nuclear Magnetic Resonance, 2015

Molecular motions in poly(ethylene-co-norbornene) were studied in a temperature range well below ... more Molecular motions in poly(ethylene-co-norbornene) were studied in a temperature range well below its glass transition point by a few techniques based on the NMR phenomenon. Temperature dependencies of proton spin-lattice relaxation times T1 (at 200MHz and at 30.2MHz), proton spin-lattice relaxation time in the rotating frame T1ρ (at 68kHz) and frequency dispersion of proton spin-lattice off-resonance relaxation times in the rotating frame T1ρ(off) were determined for the copolymer. Analysis of (1)H NMR relaxation data permitted characterization of local motions occurring in the copolymer i.e. rotation of methyl groups around C3 axes, reorientations of methylene groups and motions of segments of polymer chains including norbornene groups.

Synthetic Metals, 2015

In this work we report a reproducible and efficient method of surface modification of titania nan... more In this work we report a reproducible and efficient method of surface modification of titania nanoparticles (rutile) via reversible-deactivation radical polymerization. Herein, we graft poly(di (ethylene glycol) methyl ether methacrylate) from the surface of TiO 2 in an amount of 21 wt% within the reaction time of 3 h 15 min. The amount of grafted polymer was assessed by Thermogravimetric Analysis and it is one of the highest reported till now for this ceramic nanoparticles by atom transfer radical polymerization. The properties of inorganic-organic, i.e. core-shell material, as well as of pristine TiO 2 and neat polymer were examined by Infrared and Dielectric Spectroscopies. The shape of the nanoparticles and the thickness of the polymer coating shell were investigated by means of High Resolution Transmission Electron Microscopy. The obtained nanocomposite exhibits dielectric permittivity e 0 = 18 and loss tangent around 1 Â10 À2 at 20 C. The described method allows controlling a length and chemical structure of the grafted polymer from ceramic core, thus to tailor a physical properties of nanoparticles and of nanocomposites.

Solid State Nuclear Magnetic Resonance, 1995

dependences of proton and fluorine second moments and spin-lattice relaxation time T, below glass... more dependences of proton and fluorine second moments and spin-lattice relaxation time T, below glass transition were measured in glassy "I-Do,Pip-Me-BF," ionene. The existence of motions of methyl groups and segments linking the cationic centers, namely piperidinium rings and trimethylene groups, for the polymeric part of ionene were established. Isotropic rotation of the counter-ion was evidenced and its limited diffusion suggested. To interpret the proton and fluorine relaxation data, a Davidson-Cole distribution of correlation times was assumed. 0926-2040/95/$09.50 0 1995 Elsevier Science B.V. All rights reserved SSDI 0926.2040(95)00013-5

Polymer, 2010

Dynamic mechanical studies of molecular dynamics have been performed for two ethylene-norbornene ... more Dynamic mechanical studies of molecular dynamics have been performed for two ethylene-norbornene copolymers. The analysis of data indicates the existence of three relaxation processes: a primary (a) and two secondary (b and g) ones. It was found that the secondary processes b and g are connected with the local motions of ethylene and norbornene groups, respectively and that their rates follow the Arrhenius relation. Moreover, the b process was recognized as the Johari-Goldstein process acting as the precursor of the cooperative structural a-relaxation. Contrary to g and b processes, the motional rate of a-one follows the Vogel-Fulcher-Tammann equation indicating the cooperative nature of motions involved in this process. An increase in norbornene content in copolymer slows down the molecular dynamics of both norbornene fragments and whole chains, and in consequence shifts these relaxation processes into higher temperatures. Using the Havriliak-Negami formalism the motional parameters for the processes mentioned above were estimated.

Polymer, 2011

Structural behavior of miktoarm star polymers comprising poly(butyl acrylate) (PBA) and poly(ethy... more Structural behavior of miktoarm star polymers comprising poly(butyl acrylate) (PBA) and poly(ethylene oxide) (PEO) arms was studied by means of Differential Scanning Calorimetry (DSC), Wide Angle X-Ray Scattering (WAXS), Polarized Optical Microscopy (POM) and Fourier Transform Infrared Spectroscopy (FTIR) methods. The aim of this study was to correlate changes in the composition of the arms of the PBA/ PEO miktoarm star polymers with their structures. As a consequence of increasing PBA content, the decrease in crystallinity of the studied PBA/PEO heteroarm star copolymers was observed. Regardless of the copolymer composition, fraction of oxyethylene units in the crystalline PEO phase was similar in all investigated systems. The POM images showed spherulitic morphology of the materials having low PBA content, while an increase in PBA arms fraction leads to the formation of less ordered structures. The analysis of FTIR vibrational spectrum indicates helical conformation of PEO chains in the crystalline phase. Isothermal crystallization studies carried out using the FTIR technique suggest the existence of isolated domains in the nanoscopic scale of investigated materials.

Macromolecular Chemistry and Physics, 2007

Journal of Non-Crystalline Solids, 2010

Molecular dynamics of polyisoprene, polystyrene and poly(styrene-b-isoprene) diblock copolymer ha... more Molecular dynamics of polyisoprene, polystyrene and poly(styrene-b-isoprene) diblock copolymer has been studied by means of broadband dielectric and magnetic resonance spectroscopies. The measurements of dielectric permittivity as well as NMR second moment, spin-lattice relaxation times T 1 and T 1q in wide range of temperature were performed. It was found that the copolymer exhibits all motions observed in the neat components i.e., three motions connected with polyisoprene blocks (segmental, normal-mode and methyl group rotation) and one (segmental) related to polystyrene blocks. The mutual interaction between polystyrene and polyisoprene chains leads to stiffening of polyisoprene blocks and loosening of polystyrene structure. The polyisoprene segmental and normal-mode motions were analyzed in terms of the Havriliak-Negami model and Vogel-Fulcher-Tamman (VFT) relation. Based on NMR spin-diffusion experiment the size of polystyrene domains in copolymer was evaluated and accounts to 9 nm.

Journal of Non-Crystalline Solids, 2010

Rheological and dielectric behavior of linear PDMS and alkyl-modified PDMS melts has been studied... more Rheological and dielectric behavior of linear PDMS and alkyl-modified PDMS melts has been studied. Molecular dynamics of linear PDMS, being a model of grafted polydimethylsiloxanes studied, has been examined carefully with particular attention paid to its ability to form the semicrystalline phase. Random incorporation of alkyl groups into PDMS chain has been shown to prevent the polymer crystallization. The glass transition temperature of the grafted PDMS changes proportionally to the modifier content.

European Polymer Journal, 2002

1 H and 13 C NMR spectra and 1 H spin-lattice relaxation times T 1 and T 1q have been employed to... more 1 H and 13 C NMR spectra and 1 H spin-lattice relaxation times T 1 and T 1q have been employed to study the structure and molecular dynamics in polyethylene and ethylene-1-butene copolymer in the temperature range from 100 to 370 K. Results are interpreted in terms of a, b and c -relaxation, as well as methyl group rotation. The activation energies for all motions were established. The incorporation of 1-butene into ethylene chain leads to an increase of mobility in amorphous and crystalline phases as well as appearance the 13 C resonance characteristic to the monoclinic structure in addition to the orthorhombic observed in both polymers. The crystallinity degree derived from T 1q in studied polymers is close to that determined using DSC method. Ó

European Polymer Journal, 2013

The nuclear magnetic resonance (NMR) and dielectric spectroscopy (DS) methods were used to invest... more The nuclear magnetic resonance (NMR) and dielectric spectroscopy (DS) methods were used to investigate the segmental and global dynamics in lamellar microphase separated poly(styrene-b-isoprene) (SI) diblock copolymer. For the first time, the susceptibility representation of the NMR relaxation data is applied to the analysis of the molecular dynamics in complex polymer systems like the diblock copolymer. This approach in combination with the frequency-temperature superposition (FTS) allows one to compare directly the NMR and DS data in an extended frequency range providing a unique comprehensive picture of various relaxation processes present in the system studied. The findings of these investigations include structural relaxations of the polyisoprene (PI) and the polystyrene (PS) blocks, a normal mode relaxation of the PI block, and an extra low frequency interfacial relaxation. Special attention has been devoted to influence of the copolymer morphology on the segmental and global dynamics in PI.