Reversible actuation ability upon light stimulation of the smart systems with controllably grafted graphene oxide with poly (glycidyl methacrylate) and PDMS elastomer: Effect of compatibility and graphene oxide reduction on the photo-actuation performance

This study is focused on the controllable reduction of the graphene oxide (GO) during the surface-initiated atom transfer radical polymerization technique of glycidyl methacrylate (GMA). The successful modification was confirmed using TGA-FTIR analysis and TEM microscopy observation of the polymer shell. The simultaneous reduction of the GO particles was confirmed indirectly via TGA and directly via Raman spectroscopy and electrical conductivity investigations. Enhanced compatibility of the GO-PGMA particles with a polydimethylsiloxane (PDMS) elastomeric matrix was proven using contact angle measurements. Prepared composites were further investigated through the dielectric spectroscopy to provide information about the polymer chain mobility through the activation energy. Dynamic mechanical properties investigation showed an excellent mechanical response on the dynamic stimulation at a broad temperature range. Thermal conductivity evaluation also confirmed the further photo-actuation capability properties at light stimulation of various intensities and proved that composite material consisting of GO-PGMA particles provide systems with a significantly enhanced capability in comparison with neat GO as well as neat PDMS matrix. © 2018 by the authors.Czech Science Foundation [16-20361Y]; Ministry of Education, Youth and Sports of the Czech Republic-program NPU I [L01504]; Operational Program Research and Development for Innovations - the European Regional Development Fund (ERDF); project CPS-strengthening research capacity [CZ.1.05/2.1.00/19.0409]; [APVV-15-0545]; [APVV-14-0891

Polylactide-based nonisocyanate polyurethanes: Preparation, properties evaluation and structure analysis

This study investigated the successful synthesis and characterization of nonisocyanate polyurethanes (NIPUs) based on polylactide. The NIPUs were synthesized by a condensation reaction of oligomers with hard segments (HSs) and synthesized carbamate-modified polylactic acid containing flexible segments (FSs). The oligomers with HSs were prepared from phenolsulfonic acid (PSA) or a mixture of PSA and hydroxynaphthalenesulfonic acid (HNSA), urea and formaldehyde. The mixing of oligomeric compounds with different amounts of formaldehyde was carried out at room temperature. Obtained NIPU samples with different hard segment content were tested for their mechanical and thermal properties. The tensile strength (TS) of all NIPU samples increased with an increasing amount of HSs, attaining the maximum value at an HS:FS ratio of 1:3. Samples prepared from PSA and HNSA showed higher tensile strength (TS) without significant change in elongation at break compared to the samples based only on PSA. Thermogravimetric analysis data indicated an absence of weight loss for all samples below 100 °C, which can be considered a safe temperature for using NIPU materials. Maximum degradation temperatures reached up to 385 °C. Fourier transform infrared spectroscopy results confirmed the existence of expected specific groups as well as the chemical structure of the prepared polyurethanes. DSC analysis showed the existence of two characteristic phase transitions attributed to the melting and crystallization of hard segments in the NIPU samples.Ministerstwo Edukacji i Nauki, MNiSWCentre of Polymer Systems (Tomas Bata University in Zlin, Czech Republic), within the project "Strengthening research capacity [CZ.1.05/2.1.00/19.0409, LO1504, 3269/32/P]; Polish Ministry of Science and Higher Educatio

The UV photodegradability study of octadecaborane in polystyrene matrix thin films

Octadecaborane was announced in the literature as a new laser dye delivering blue luminescence with high quantum yield. To unlock the potential of this class of compounds in electronics, a representative of octadecaboranes, anti-B18H22, was preliminarily investigated as a dopant to polystyrene matrix. Polymer/borane thin films with thickness varying in the range of hundreds of nanometres were deposited onto quartz substrates by spin coating technique from solutions in organic solvents. The UV degradability of prepared samples was studied by fluorimetric observation. Effects of the surrounding atmosphere, the dopant concentrations and the molecular structure were observed, which has implications towards the reliability of studied materials in prospective applications in optoelectronic devices. © 2021 TANGER Ltd., Ostrava.Czech Science FoundationGrant Agency of the Czech Republic [19-23513S]; Operational Program Research and Development for InnovationsEuropean Commission; project CPS -strengthening research capacity [CZ.1.05/2.1.00/19.0409]Grantová Agentura České Republiky, GA ČR: 19-23513S; European Regional Development Fund, ERDF: CZ.1.05/2.1.00/19.040

Temperature dependence of vibrational motions of thin polystyrene films by infrared reflection-absorption spectroscopy: A single measurement tool for monitoring of glass transition and temperature history

A method for monitoring of vibrational response and temperature region of glass transition by a single analysis is introduced with the use of an otherwise well-known spectroscopic method. The temperature-dependent changes of polystyrene (PS) thin films were investigated by polarization-modulated infrared reflection-absorption spectroscopy. The study revealed that changes in individual spectral regions with the temperature increase are specific and provide the relation to the processing and thermal history of the thin film. Temperature responses of infrared spectral region areas; an abrupt change of Car-H stretching, a step-like change of Car-H out-of-plane bending, a linear decrease of C–H stretching and C–H bending area, granted information on the temperature domain represented by local molecular motion change (β-transition) of PS. The different behavior of spectral regions is rationalized by consideration of vibrational free volume contribution to the total free volume of the system that is certainly influenced by functional groups nature, such as their size, geometry and involvement of non-bonding interaction. © 2021 The AuthorsCzech Science FoundationGrant Agency of the Czech Republic [19-23513S]; Operational Program Research and Development for InnovationsEuropean Commission; European Regional Development Fund (ERDF)European Commission; national budget of the Czech Republic [CZ.1.05/2.1.00/19.0409]; Ministry of Education, Youth and Sports of the Czech Republic - DKRVO [RP/CPS/2020/006]RP/CPS/2020/006; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; Grantová Agentura České Republiky, GA ČR: 19-23513S; European Regional Development Fund, ERDF: CZ.1.05/2.1.00/19.040

Polystyrene thin films with incorporated borane clusters for electronic applications investigated by infrared reflection-absorption spectroscopy

The paper is focused on the investigation of thin polystyrene (PS) films and PS films with incorporated anti-octadecaborane(22) (anti-B18H22) clusters (PS+B18H22) with a thickness of 450 nm and 290 nm, respectively. The main aim is to describe the vibrational behavior of thin films in dependence on temperature and determine the changes connected with the glass transition of PS. Infrared reflection-absorption spectra were measured and from the plot of spectral region area (Arange) vs. temperature, glass transition temperature (Tg) of PS was extracted. The abrupt change in the course of A of Car-H stretching vs. temperature was assigned to the glass transition. Tg of PS and PS+B18H22 thin film was determined to be 74 °C and 77 °C, respectively. On the other hand, only a continuous decrease of A of C-H stretching vs. temperature was found for both samples indicating that each vibrational motion reacts uniquely on temperature increase. It was further found that anti-B18H22 is not fixed firmly in the thin layer at higher temperatures, because no B-H spectral response was detected above 91 °C. This result was also supported with TGA and DSC analysis showing a particular mass decrease at temperature 75 °C. © 2021 TANGER Ltd., Ostrava.Czech Science FoundationGrant Agency of the Czech Republic [19-23513S]; Operational Program Research and Development for InnovationsEuropean Commission; project CPS - strengthening research capacity [CZ.1.05/2.1.00/19.0409]Grantová Agentura České Republiky, GA ČR: 19-23513S; European Regional Development Fund, ERDF: CZ.1.05/2.1.00/19.040

The temperature dependence of the photoluminescence stability of octadecaborane in polystyrene matrix thin films

The novel boron-hydride cluster compound (anti-B18H22) has been recently introduced as potential laser dye and interesting molecule for organic electronics. Blue light-emitting devices or photoluminescence (PL) sensors will be highly desirable. Nevertheless, the issue of their temperature stability may be critical for the use of this compound family as active molecules or at least fluorescence labels for any application. This contribution deals with the preparation and characterization of borane-polystyrene blend thin films. The influence of thermal history on the emission properties of prepared films was investigated. Based on the performed study, a set of critical limits and implications for the future molecular design was defined. © 2021 TANGER Ltd., Ostrava.Czech Science FoundationGrant Agency of the Czech Republic [19-23513S]; Operational Program Research and Development for InnovationsEuropean Commission; project CPS - strengthening research capacity [CZ.1.05/2.1.00/19.0409]Grantová Agentura České Republiky, GA ČR: 19-23513S; European Regional Development Fund, ERDF: CZ.1.05/2.1.00/19.040

Incorporation of the new anti-octadecaborane laser dyes into thin polymer films: A temperature-dependent photoluminescence and infrared spectroscopy study

New anti-octadecaborane(22) laser dyes have been recently introduced. However, their application in solid thin films is limited, despite being very desirable for electronics. Spectroscopic methods, photoluminescence (PL), and infrared reflection-absorption spectroscopy (IRRAS), are here used to reveal structural responses to a temperature change in thin polymer films made of pi- and sigma-conjugated and non-conjugated polymers and anti-octadecaborane(22) and its tetra-alkylatedderivatives. It has been observed that borane clusters are not firmly fixed within polymer matrices and that their ability for diffusion out of the polymer film is unprecedented, especially at higher temperatures. This ability is related to thermodynamic transitions of polymer macromolecular chains. PL and IRRAS spectra have revealed a clear correlation with beta-transition and alpha-transition of polymers. The influence of structure and molecular weight of a polymer and the concentration and the substitution type of clusters on mobility of borane clusters within the polymer matrix is demonstrated. A solution is proposed that led to an improvement of the temperature stability of films by 45 degrees C. The well-known spectroscopic methods have proved to be powerful tools for a non-routine description of the temperature behavior of both borane clusters and polymer matrices.Czech Science Foundation [19-23513S]; Operational Program Research and Development for Innovations; national budget of the Czech Republic [CZ.1.05/2.1.00/19.0409]; Ministry of Education, Youth and Sports of the Czech Republic-DKRVO [RP/CPS/2022/007]RP/CPS/2022/007; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; Grantová Agentura České Republiky, GA ČR: 19-23513S; European Regional Development Fund, ERDF: CZ.1.05/2.1.00/19.040

Effect of structure of polymers grafted from graphene oxide on the compatibility of particles with a silicone-based environment and the stimuli-responsive capabilities of their composites

This study reports the utilization of controlled radical polymerization as a tool for controlling the stimuli-responsive capabilities of graphene oxide (GO) based hybrid systems. Various polymer brushes with controlled molecular weight and narrow molecular weight distribution were grafted from the GO surface by surface-initiated atom transfer radical polymerization (SI-ATRP). The modification of GO with poly(n-butyl methacrylate) (PBMA), poly(glycidyl methacrylate) (PGMA), poly(trimethylsilyloxyethyl methacrylate) (PHEMATMS) and poly(methyl methacrylate) (PMMA) was confirmed by thermogravimetric analysis (TGA) coupled with online Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Various grafting densities of GO-based materials were investigated, and conductivity was elucidated using a four-point probe method. Raman shift and XPS were used to confirm the reduction of surface properties of the GO particles during SI-ATRP. The contact angle measurements indicated the changes in the compatibility of GOs with silicone oil, depending on the structure of the grafted polymer chains. The compatibility of the GOs with poly(dimethylsiloxane) was also investigated using steady shear rheology. The tunability of the electrorheological, as well as the photo-actuation capability, was investigated. It was shown that in addition to the modification of conductivity, the dipole moment of the pendant groups of the grafted polymer chains also plays an important role in the electrorheological (ER) performance. The compatibility of the particles with the polymer matrix, and thus proper particles dispersibility, is the most important factor for the photo-actuation efficiency. The plasticizing effect of the GO-polymer hybrid filler also has a crucial impact on the matrix stiffness and thus the ability to reversibly respond to the external light stimulation.Grant Agency of the Czech RepublicGrant Agency of the Czech Republic [16-20361Y]; Ministry of Education, Youth and Sports of the Czech Republic program NPU I [LO1504]; Research & Innovation Operational Programme - ERDF [313021T081]; project VEGAVedecka grantova agentura MSVVaS SR a SAV (VEGA) [2/0129/19]; European UnionEuropean Union (EU) [CZ.02.2.69/0.0/0.0/16_027/0008464]; Operational Program Research and Development for innovations; European Regional Development Fund (ERDF)European Union (EU); national budget of Czech Republic within project CPS -strengthening research capacity [CZ.1.05/2.1.00/19.0409]; National Science Centre, Poland [UMO-2016/23/P/ST5/02131]; European Unions' Horizon 2020 research and innovation programme under Marie Sklodowska-Curie grant [665778

Giant response and selectivity of Hansen solubility parameters-based graphene-SBS co-polymer matrix composite room temperature sensor to organic vapours

A styrene-butadiene-styrene co-polymer matrix nanocomposite filled with graphene nanoplatelets was studied to prepare chemiresistive volatile organic compounds (VOCs) room temperature sensors with considerable response and selectivity. Nanofiller concentration was estimated from the electrical conductivity percolation behaviour of the nanocomposite. Fabricated sensors provided selective relative responses to representative VOCs differing by orders of magnitude. Maximum observed average relative responses upon exposure to saturated vapours of the tested VOCs were ca. 23% for ethanol, 1600% for acetone, and the giant values were 9 × 106% for n-heptane and 10 × 106% for toluene. The insensitivity of the sensor to the direct saturated water vapour exposure was verified. Although high humidity decreases the sensor’s response, it paradoxically enhances the resolution between hydrocarbons and polar organics. The non-trivial sensing mechanism is explained using the Hansen solubility parameters (HSP), enabling a rational design of new sensors; thus, the HSP-based class of sensors is outlined.DKRVO, (RP/CPS/2022/007); Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; Univerzita Tomáše Bati ve Zlíně, UTB, (IGA/CPS/2022/002, IGA/CPS/2023/006)Ministry of Education, Youth, and Sports of the Czech Republic-DKRVO [RP/CPS/2022/007]; Tomas Bata University in Zlin [IGA/CPS/2022/002, IGA/CPS/2023/006

The photostability of novel boron hydride blue emitters in solution and polystyrene matrix

In recent work, the boron hydride anti-B18H22 was announced in the literature as a new laser dye, and, along with several of its derivatives, its solutions are capable of delivering blue luminescence with quantum yields of unity. However, as a dopant in solid polymer films, its luminescent efficiencies reduce dramatically. Clarification of underlying detrimental effects is crucial for any application and, thus, this contribution makes the initial steps in the use of these inorganic compounds in electrooptical devices based on organic polymer thin films. The photoluminescence behavior of the highly luminescent boron hydrides, anti-B18H22 and 3,3 ',4,4 '-Et-4-anti-B18H18, were therefore investigated. The quantum yields of luminescence and photostabilities of both compounds were studied in different solvents and as polymer-solvent blends. The photophysical properties of both boranes are evaluated and discussed in terms of their solvent-solute interactions using photoluminescence (PL) and NMR spectroscopies. The UV degradability of prepared thin films was studied by fluorimetric measurement. The effect of the surrounding atmosphere, dopant concentration and the molecular structure were assessed.Czech Science FoundationGrant Agency of the Czech Republic [19-23513S]; Operational Program Research and Development for InnovationsEuropean Commission; European Regional Development Fund (ERDF)European Commission; national budget of the Czech Republic [CZ.1.05/2.1.00/19.0409