Diarylcarbenes have been shown to be suitable for the surface modification of a diverse range of polymers, including low surface energy materials, and this allows the modification of surface macroscopic effects, exemplified by changes in wetting behaviour, pH sensing, and bactericidal activity.

Polymer surface modification can be used for the modification of low surface energy materials. This can be used for the control of macroscopic behaviour, depending on the identity of the chemical functional group introduced at the surface. The method has been exemplified for the modification of wetting behaviour and the introduction of bactericidal properties.

Kinetic Monte Carlo simulations are performed to investigate the capability of ICAR ATRP for the synthesis of well-defined poly(isobornyl acrylate-b-styrene) block(-like) copolymers using one-pot semi-batch and two-pot batch procedures. The block copolymer quality is quantified via a block deviation (〈BD〉) value. For 〈BD〉 values lower than 0.30, the quality is defined as good and for well-chosen polymerization conditions the formation of homopolymer chains upon addition of the second monomer can be suppressed. A better block quality is obtained when isobornyl acrylate is polymerized first. For lower Cu levels a one-pot semi-batch procedure allows a much faster ATRP and better control over the polymer properties than a two-pot batch procedure.

One-pot semi-batch and two-pot batch ICAR ATRP procedures in bulk for the synthesis of well-defined poly(iBoA-b-Sty) diblock copolymers are analyzed in detail via kinetic Monte Carlo simulations. The effect of temperature and Cu ppm level is considered in both procedures and a block deviation value, 〈BD〉, is introduced as a new copolymer property to characterize the quality of the block copolymer.

The polymerization that IUPAC terms reversible-deactivation radical polymerization is a controlled radical polymerization technique (CRP) that allows producing polymers with tailored properties without the stringent conditions typical in ionic polymerization. A theoretical analysis is presented of the influence of operating and design conditions on the product properties for the nitroxide-mediated copolymerization (NMP) of styrene and α-methyl styrene. Several reactor configurations are analyzed, with different feeding policies and temperature profiles. To this end a mathematical model is developed to predict copolymer average properties and the complete bivariate MWD. The results help establishing design parameters and optimal operating policies to obtain desired copolymer microstructures.

A mathematical model is presented of the nitroxide mediated copolymerization of styrene and α-methyl styrene, capable of predicting the average properties of the resulting material and the full bivariate molecular weight distribution. It is applied to different reactor configurations with several feeding policies and temperature profiles. The model shows promise for its application in an optimization tool for controlled radical polymerization processes.

Styrene/acrylonitrile (SAN) copolymers with low polydispersity (1.10–1.30) are synthesized by nitroxide mediated polymerization (NMP) in dimethylformamide (DMF) solution with a succinimidyl ester (NHS) terminal group from the N-tert-butyl-N-[1-diethylphosphono-(2,2-dimethylpropyl) nitroxide] (SG1) residue. These copolymers are thermally stabilized by removing the SG1, and then modified to form primary amine end-functional SAN (SAN-NH₂). Proton nuclear magnetic resonance spectroscopy (¹H NMR) and Fourier-transform infrared spectroscopy (FT-IR) indicated that the amine group is effectively placed at the chain end at a level of 90%. SAN-NH₂ is reactively blended with maleic anhydride grafted poly(ethylene) (PE) at 20 wt.% loading at 180 °C and the resulting morphology is compared against the non-reactive blend. Scanning electron microscopy (SEM) indicates finer SAN domains ∼ 1 µm which are thermally stable upon annealing in the reactive case. The dispersed SAN domains are reoriented using a channel die to impart elongated domains with aspect ratios ∼ 14, which would be desirable for barrier materials.

Amine end functional poly(styrene-acrylonitrile) (SAN) polymers are synthesized using nitroxide mediated polymerization for use in reactive extrusion with maleic anhydride grafted poly(ethylene). The synthesis and modification of the polymers is described, as well as a study into the microstructure of the polymer blends. Blend microstructure is modified to form lamellar domains of SAN.

The importance of diffusional limitations in controlled radical polymerization at laboratory scale and in homogeneous medium is highlighted using different diffusion models. In particular, a coupled ‘parallel’ encounter pair model is introduced which allows a rigorous description of the influence of diffusional limitations on the activation/deactivation process. Diffusional limitations on termination have a significant influence, whereas those on the activation/deactivation process can disturb the regular growth pattern at high conversion if the mediating agent is a sufficiently bulky species. Diffusional limitations on initiation are only important in case radical initiator is still present at high conversion.

The impact of diffusional limitations for three important controlled radical polymerization (CRP) techniques at a laboratory scale and in homogeneous media considering the most important diffusion models and styrene as the monomer are discussed. The formulated insights contribute to a better understanding of CRP processes in the frame of their potential industrial realization.

Styrene polymerization literature is reviewed and a model with dicumyl peroxide and benzoyl peroxide initiators is developed. Nine parameters are selected for estimation using statistical methods that account for the influence of parameters on model predictions, correlated effects of parameters and uncertainties of initial literature values. Updated parameters result in improved fits to conversion and molecular weight data from three research groups, reducing the least-squares objective function by 73%. Use of industrial data from 19 batch reactor runs increases the number of estimable parameters to 16. Good predictions are obtained for validation runs with temperature ramps using both initiators.

A literature review of efforts to model the polymerization of styrene under industrial manufacturing conditions is presented. A formal statistical approach is used to select and estimate model parameters and model predictions are compared with literature data obtained using dicumyl peroxide and benzoyl peroxide initiators. Industrial polymerization data are used to validate the model.

In-reactor blends of ultra-high molecular weight polyethylene (UHMW-PE) and medium molecular weight polyethylene (mMW-PE) were prepared by precise multi-stage slurry polymerizations (MSP). Correlations between polymerization conditions and mechanical properties of in situ mixed polyolefins were investigated. Reactor powders were brought to shape through compression molding. Izod impact strength, dynamic mechanical analysis (DMA), and tensile properties, as well as physical properties (density, crystalline properties) were measured and evaluated in comparison with physical blends and commercial PE grades. In-reactor blends show a higher material stiffness and impact properties increased by a factor of 2 compared to unimodal materials and physical blends. Thus the MSP-method offers an efficient way to improve mechanical behavior of linear high-molecular weight PE.

The effects of multi-stage (slurry) polymerization on mechanical properties of in-reactor blended UHMW-PE materials is presented, and it is shown that due to a controlled polymerized particle morphology, mechanical properties, such as impact properties can be regulated.

A rigorous method is developed to extract kinetic parameters describing catalyst activity from experimental polymerization rate profiles for Ziegler–Natta catalysts. The kinetic scheme used correlates the oxidation state with catalyst activity, eliminating the need for multiple site types to describe rate profiles. The method is applied to data from kinetic experiments performed in a lab-scale semi-batch reactor. Four parameters are required to describe the activity of the catalyst: the polymerization rate constant and three site transformation rate constants. The model is able to reproduce changes in the rate profiles in response to reactant concentrations. The fits of the model to the data are comparable to those in similar studies.

The activity of Ziegler–Natta catalysts for ethylene polymerization is studied, and a method developed to extract meaningful kinetic parameters from experimental data. Four model parameters are required to reproduce polymerization rate profiles for a range of laboratory experimental conditions.

Cover: A strategy to reliably reconstruct 3D images of porous polyolefin particles using X-ray microtomography is presented. Polyolefins exhibit low absorptivity for X-rays, hence they represent challenging samples for mCT imaging. Exploration of the influence of scanning/reconstruction settings on the resulting polymer morphology and transport characteristics allows the generation of these cross-sectional images of polyethylene and polystyrene particles, shown with different smoothing parameters. Further details can be found in the article by L. Meisterová, A. Zubov, K. Smolná, F. Štěpánek, and J. Kosek* on page 277.

A mathematical model is developed for condensation polymerization of 1,3-propanediol to produce Cerenol polyether. The effect of the super-acid catalyst is considered explicitly in the proposed reaction mechanism. The main reactions include protonation/deprotonation equilibrium, polycondensation, carbocation formation, end degradation, and transetherification. Formation of propanal and secondary hydroxyl ends is also considered. Mass transfer of water, propanal, and monomer from the liquid phase into nitrogen bubbles is included in the model. The proposed model predicts the time evolution of number average molecular weight and concentrations of water, propanal, monomer, and unsaturated end groups, along with evaporation rates of small molecules. Data from isothermal batch experiments are used to estimate model parameters. Steep upward trends in degree of polymerization and in concentration of unsaturated ends are not predicted well at long reaction times based on the current model.

A dynamic model simulates condensation polymerization of 1, 3-propanediol to produce polyether. The reaction mechanism accounts for the effect of super-acid catalyst. Parameters are estimated from batch reactor data. The model predicts time evolution of degree of polymerization and degraded ends. Concentrations of water, monomer, and propanal in the liquid phase and evaporation rates of these species are predicted.

In this work, ethylene/1-hexene copolymerization with a novel SiO₂-supported inorganic and organic hybrid chromium-based catalyst was investigated. This catalyst was prepared using the residual surface hydroxyl groups in Phillips catalyst to support bis(triphenylsilyl) chromate (BC) in order to get the merits from two important chromium-based catalysts namely inorganic Phillips and organic S-2 catalysts. The influences of addition amount of 1-hexene and BC were systematically investigated. With increasing 1-hexene from 0 to 7 vol%, the activity of HCat-2 catalyst showed a decreasing tendency. Its copolymer also showed the better short chain branches distribution through the temperature rising elution fractionation cross successive self-nucleation and annealing characterization.

Ethylene/1-hexene copolymerization with a novel SiO₂-supported hybrid chromium-based catalyst is investigated. This catalyst is prepared using the residual surface hydroxyl groups in Phillips catalyst to support bis(triphenylsilyl) chromate in order to attain the merits of two important chromium-based catalysts, namely inorganic Phillips and organic S-2 catalysts. The copolymer shows better short chain branch distribution.

Batch radical polymerization of non-ionized methacrylic acid, 30 wt.-% in aqueous solution, has been studied at 50 °C and ambient pressure with 2-mercaptoethanol (ME) as the chain-transfer agent (CTA). Initial polymerization rate decreases with CTA concentration, which has been varied up to 20 mol-%. A kinetic model is presented which includes chain-length-dependent termination and uses an empirical function to account for the dependence of termination rate on both monomer conversion and molar mass of the polymeric product. In conjunction with PREDICI simulation, this model affords for an adequate representation of the measured monomer conversion vs. time profiles.

Kinetics of methacrylic acid radical polymerization in aqueous solution, with chain transfer by 2-mercaptoethanol, are measured and modeled with the dependence of termination rate on radical chain length, on monomer conversion, and on polymer molar mass being taken into account. PREDICI simulation allows for an adequate representation of measured monomer conversion vs. time profiles.

Advanced models of penetrant transport and reaction in spatially 3D porous polyolefin particles reconstructed from X-ray µCT images require proper determination of particle morphology. Moreover, polyolefins exhibit a relatively low absorptivity for X-rays, therefore their investigation using µCT can be difficult. In this paper, a low-resolution µCT built into an SEM is used to examine how the µCT resolution and several user-selected parameters associated with the scanning/reconstruction affect the resulting particle morphology. Using samples with known morphology and independent imaging techniques, the performance of the µCT device is critically assessed. Finally, a method suitable for the reliable reconstruction of polyolefin particles using low-resolution µCT is proposed.

A robust strategy for reliable 3D reconstruction of porous polyolefin particles using X-ray micro-tomography is presented. Polyolefins exhibit low absorptivity for X-rays, hence they represent challenging samples for µCT imaging. The influence of scanning/reconstruction settings on the resulting polymer morphology and transport characteristics is investigated.