Under the validity of the degenerative transfer mechanism, the activation/deactivation process in reversible addition-fragmentation chain transfer (RAFT) polymerization can be formally quantified by transfer coefficients, depending on the chemical structure of the participating radicals and dormant species. In the present work, the different literature methods to experimentally determine these RAFT transfer coefficients are reviewed and theoretically re-evaluated. The accuracy of each method is mapped for a broad range of reaction conditions and RAFT transfer reactivities. General guidelines on when which method should be applied are formulated.

**Under the validity of the degenerative transfer mechanism,** the activation/deactivation process in reversible addition-fragmentation chain transfer (RAFT) polymerization can be formally quantified by transfer coefficients. In the present work, the different literature methods to experimentally determine these RAFT transfer coefficients are reviewed and theoretically re-evaluated. General guidelines on when which method should be applied are formulated.

The crosspropagation of 1-ethylcyclopentyl methacrylate (ECPMA) and methyl methacrylate (MMA) has been studied using a combination of quantum chemistry calculations and experiment. Our computational work utilizes a trimer-to-tetramer reaction model, coupled with an ONIOM (B3LYP/6-31G(2df,p): B3LYP/6-31G(d)) method for geometry optimization and an M06-2X/6-311+G(2df,p) method plus SMD solvation model for single point energy calculations. The results show several trends: the identity of the ultimate unit of a trimer radical affects not only the preferred conformation of the region where the reaction takes place, but also the reactivity of the radical; the addition of an ECPMA monomer to the radicals is generally favored compared to an MMA monomer; the pen-penultimate unit of a trimer radical shows a nonnegligible entropic effect; the penultimate unit effect is implicit for the ECPMA–MMA copolymer system. Finally, terminal model reactivity ratios fitted based on the explicit rate coefficients calculated from the quantum chemical results are compared with those from experimental measurements. The computations not only agree qualitatively with experimentally derived results in terms of the selectivity of ECPMA–MMA crosspropagation, but also give reasonable quantitative predictions of reactivity ratios.

**Understanding the kinetics of copolymerization of different methacrylates** is crucial for the development of their industrial applications. Quantum chemistry and a trimer-to-tetramer model is used to reveal the details of crosspropagation kinetics of 1-ethylcyclopentyl methacrylate and methyl methacrylate. Predicted terminal model reactivity ratios fitted from the calculations agree well with experimental data.

The coil-globule transition of short hydrophobic-polar (HP) chains, composed of 24 hydrophilic monomers and 24 polar monomers, in solution and on hydrophobic surface and the adsorption of the HP chain on hydrophobic surface are simulated. The coil-globule transition point of the HP chain is dependent on sequence of chain but is roughly independent of the surface adsorption strength. Whereas the critical adsorption point of the HP chain is roughly independent of sequence. In addition, the lowest energy states can be obtained for the HP chain in solution or on surface by Monte Carlo simulated annealing method. Results show that the statistical conformation is strongly dependent on the intrachain H-H attraction strength and the surface adsorption strength.

**The coil-globule transition of short hydrophobic-polar (HP) chains,** composed of 24 hydrophilic monomers and 24 polar monomers, on hydrophobic surface is simulated by using Monte Carlo simulated annealing method. The coil-globule transition point is dependent on sequence of chain but is roughly independent of the surface adsorption strength. The lowest energy states can be obtained for the HP chain even on surface.

Theoretical considerations and Monte Carlo simulations have proved that the microstructure of copolymer chains in living reversible copolymerization can be effectively described by the first-order Markov chain process only when the system space of this process reaches chain lengths above the number-average degree of polymerization (DP_{n}). The time scale of equilibration depends mostly on DP_{n} of the product, rate constants of depropagation, as well as on the equilibrium microstructure of copolymer. During the process, evolution encompasses, besides the chain-length distribution like in homopolymerization, also the chain microstructure. The kinetically determined microstructure (gradient, alternate, etc.) observed in the first stage of copolymerization is related to reactivity ratios. It evolves into the equilibrium microstructure, determined exclusively by the equilibrium constants and initial conditions. Discussion of this evolution together with the statistical description of the reversible binary copolymerization systems at various stages of equilibration is given.

**Equilibrium copolymerization** evolves from initial stage resembling irreversible copolymerization through the second stage when comonomers are consumed reaching steady state condition to its equilibrium in the longest third stage. Chain-length distribution, copolymer composition, and copolymer microstructure change as well, depending on rate constants and initial conditions. Time of reaching equilibrium is proportional to the squared DP_{n[max]} of the product.

In surface-initiated atom transfer radical polymerization, knowledge of grafting density is of significant interest because it is one of the determining properties of grafted polymer. It is well known that not all of the immobilized initiators can grow into polymer chains. However, little is known about why this happens and what affects the grafting efficiency. The lack of information is partly due to the difficulty in experimental determination of grafting density on flat substrates. To circumvent the problem, Monte Carlo simulation with bond fluctuation model is used in this study to investigate the effects of various reaction conditions on the grafting density. The simulation results show lower grafting density when less deactivator is present. In systems with lower deactivator concentration, the number of monomer added per activation cycle is higher. Coupling this with close proximity of immobilized initiators results in chains initiated at earlier time to shield their neighboring initiator moieties from adding monomers, thus lowering the grafting density in such a system. These simulation results also provide an explanation to the seemingly conflicting trend reported in the literatures.

**Various factors affecting grafting density in surface-initiated atom transfer radical polymerization** are investigated through simulation approach. It is found that the final grafting density decreased as more monomer is added between one activation and deactivation cycle due to shielding. The results can be used in conjunction with termination theory to explain the conflicting experiment trends reported in the literature.

An advanced Monte Carlo (MC) method is developed, using weight-based selection of polymer chains, to predict the molecular weight distribution (MWD) and branching level for arborescent polyisobutylene (*arb*PIB) at the end of a batch reaction. This new weight-based MC method uses differential equations and random numbers to determine the detailed structure of *arb*PIB molecules. Results agree with those from an advanced number-based MC method. The proposed weight-based algorithm requires approximately twice the computation time of the number-based method, but produces more accurate results in the high-molecular-weight portion of the MWD when the same number of polymer chains is assembled.

**New Monte Carlo method uses random numbers** and differential equations to determine structure of *arb*PIB molecules. Simulation results agree well with other MC methods, but this new MC method is more efficient on obtaining the information of higher molecular weight molecules.

Hyperbranched polymer formation during step polymerization of AB_{2} type monomer with different reactivity for the second B group is investigated to find the following universal characteristics that are invariant during the whole course of polymerization: (1) The degree of branching (DB) at large degree of polymerization (*P*) limit, , and (2) the mean square radius of gyration for the unperturbed chains having the same *P*. The value of and the universal curve for change with the reactivity ratio of two B groups; however, the universal power law holds for large polymers, irrespective of the magnitude of reactivity ratio. The exponent, 0.5, is the same as that for the random branched polymers. Similarities and differences in comparison with random branched polymer formation are discussed.

**Hyperbranched polymer formation during step polymerization of AB _{2} type monomer with different reactivity of two B's** is investigated. The mean square radius of gyration curve, as well as the degree of branching at large sized polymer limit, is invariant during the whole course of polymerization. Universal power law for large sized polymers, independent of the reactivity ratio, is also found.

Hyperbranched polymer formation during step polymerization of AB_{2} type monomer with equal reactivity of two B's is investigated theoretically, focusing the attention to the degree of branching (DB) and the mean square radius of gyration for the unperturbed chains, . It is found that the DB-value at large degree of polymerization (*P*) limit, = 0.5 is unchanged during the whole course of polymerization. The average value of having the same *P* is invariant throughout the polymerization. The universal curve between and *P* agrees perfectly with that for the self-condensing vinyl polymerization (SCVP), another method to synthesize hyperbranched polymers, when the reactivity ratio for SCVP, *r*_{SCVP}, is 2.589 that gives = 0.5. The power law, is found for large values of *P*.

**Hyperbranched polymer formation during step polymerization of AB _{2} type monomer** is investigated theoretically. When the polymer molecules are fractionated by the degree of polymerization, the universal curves for the degree of branching and the molecular dimension, which are invariant during the whole course of polymerization, are found.

Polydisperse linear polymers are studied in startup of steady shear flow simulations using dissipative particle dynamics. The results show that with an increase in polydispersity the stress overshoot declines while the steady-state stress increases. Various physical characteristics of the systems are studied including frequency of nonbonded interactions, gyration radius data, flow alignment angles, and average bond lengths. The patterns in the data suggest higher forces are necessary to orient and stretch long chain fractions in the flow direction. Relaxation modulus data prove the broad range of relaxation mechanisms in polydisperse systems. Linear viscoelasticity theory is used to quantify the relaxation spectrum. The results indicate an increase in the longest relaxation time in systems with higher polydispersity. The steady-state shear viscosity results show higher viscosities with an increase in polydispersity at all shear-rates. The good agreement of the characteristic behaviors of modeled polydisperse polymers with experiments is encouraging for future work.

**Polydisperse linear polymers are studied in startup of steady shear flow simulations** using dissipative particle dynamics. The results show that with an increase in polydispersity the stress overshoot declines while the steady-state stress increases. The broad relaxation response of polydisperse systems and the higher forces necessary to orient and stretch long chains in the flow direction result in these observations.

Nowadays, the microscopic mechanism controlling the distribution of local glass transition temperatures (*T*_{g}s) across thin polymer films is still unclear and thus large-scale applications of polymer films are restricted. Dynamic Monte Carlo simulations are performed to investigate the key factors dominating the distribution of layer *T*_{g}s in two kinds of capped ultrathin films with and without attractive polymer–substrate interactions, respectively. For the film without polymer–substrate interaction, the interfacial layer *T*_{g} is lower than the middle layer *T*_{g}. Additionally, the layer *T*_{g}s and the layer segment densities below *T*_{g} are linearly correlated, indicating that polymer density determines the distribution of layer *T*_{g}s. However, for the films with polymer–substrate interactions, the interfacial layer *T*_{g} increases dramatically with the raise of interfacial interactions, while the middle layer *T*_{g} decreases slightly. The interfacial layer *T*_{g} is proportional to the strength of interfacial interaction, while the middle layer *T*_{g} is linearly correlated with the segment density of the middle layer below *T*_{g}. Namely, interfacial interaction is the main factor dominating the interfacial layer *T*_{g}, while segment density controls the middle layer *T*_{g}.

**In film without interfacial interaction, the interfacial layer glass transition temperature ( T_{g}) is lower than the middle** layer

**Cover:** The cover shows spatial distributions of local domains of blocked segments (LDBS, red spheres) in linear and ring polymers during cooling. Linear polymers have end segments (blue spheres) with high mobility, which hinder the growth of LDBS. Thus, the LDBS in linear polymers grow more slowly at relative high temperatures compared with those in ring polymers. Further details can be found in the article by X. Ye, Z. Zhou,* Y. Nie,* P. Ma, T. Hao, W. Yang, and H. Lu on page 9.

A dynamic Monte Carlo simulation is performed to investigate the dynamical heterogeneity during cooling toward the glass transition temperature (*T*_{g}). By tracking the evolution of the probability of segment movement (PSM), it is found that the ring polymer exhibits higher *T*_{g} than that of the linear polymer. The distributions of the mean square displacements (MSDs) of segments for the two kinds of polymers indicate the presence of heterogeneous dynamics upon approaching *T*_{g}. Compared with the linear chains, the ring chains exhibit weaker dynamical heterogeneity. The relatively weak dynamical heterogeneity in the ring chains is mainly caused by the mobility difference between the gauche- and trans-conformations. The observation on the local domains of blocked segments (LDBS) demonstrates that end segments with high mobility hinder the growth of LDBS, and thus enhance the dynamical heterogeneity.

**Ring polymer has larger local domains of blocked segments,** and thus narrower distributions of segmental mobility or weaker dynamical heterogeneity. Linear polymer has end segments with high mobility, which hindered the growth of local domains of blocked segments, and therefore wider distributions of segmental mobility, namely, stronger dynamical heterogeneity.

Using self-consistent field (SCF) theory, we studied the self-assembly characteristics of polyurethane pre-polymer dispersions in aqueous solutions. With a molecularly detailed model implementing the Scheutjens–Fleer discretization scheme, it is shown how the stability, equilibrium size, and internal structure of the (swollen) micelles in polyurethane (PU) dispersions depend on the chemical structure and the molecular composition of the charged pre-polymer mixtures. The stability region of these micelles is found to increase when acid groups become deprotonated and when the ionic strength is lowered. Insight into the physical–chemical behavior of PU pre-polymer dispersions is important for the subsequent process of film formation from the PU dispersions for the final coating properties.

**Using self-consistent field (SCF) theory with a molecularly detailed model,** the authors study the self-assembly of polyurethane pre-polymer dispersions in aqueous solutions. Insight into the physical–chemical behavior of PU pre-polymer dispersions is obtained. Details like radial volume fraction distribution of six representative PU pre-polymers and water on a single swollen micelle are shown in this paper.

A mathematical model for describing the bulk free-radical polymerization of methyl-methacrylate was developed. This model includes a novel methodology for describing the diffusive step of the kinetic rate coefficients, which is based on geometric considerations and application of the Einstein diffusion Equation. The effect of polymer content and temperature on the *R*_{p} behavior is discussed in terms of the evolution of the interdependent parameters defining the *R*_{p}. The applicability of Smoluchowski equation and the importance of the translational diffusion of short radicals in the rate of termination reaction are questioned in this context. Similitudes and differences between the model results and experimental data are discussed including minima in the *R*_{p} curves at low conversions.

**The proposed model includes a novel methodology** for describing the diffusive step of the kinetic rate coefficients, which is based on geometric considerations and application of the Einstein diffusion equation instead of the Smoluchowski equation whose applicability is questioned in this context. An explanation for the rate of polymerization behavior and the onset of auto-acceleration effect is proposed.

This study focuses on the estimation and validation of some interaction parameters of the Consistent Valence Force-Field (CVFF), which are required for the calculation of thermodynamic and transport properties of oxaliplatin (a colorectal anticancer drug) in poly(lactic-co-glycolic) acids (PLGAs) matrices. Our methodology to validate the parameters for PLGAs consisted on calculation of glass transition temperature and correlations between structural properties as: fractional free volume, polymer density, and cohesive energy density using Molecular dynamic simulations. For the oxaliplatin, metal-dependent and independent interaction parameters were included into CVFF and validated with an ab-initio method (RHF/LanL2DZ). The results achieved in the present work showed that the CVFF has been wellparameterized.

**Drug delivery systems (DDS) based on poly(lactic- co-glycolic acid) nanoparticles including platinum** complexes as oxaliplatin have been recommended for the enhancement of the efficiency in colorectal cancer treatment. The influence of different factors affecting the delivering rates of oxaliplatin in this type of DDS can be analyzed through Molecular Dynamic Simulations with the adaptation of existent force-fields for organic molecules.

Five models are discussed giving the equilibrium constant for the catenation of two ring oligomers as a function of their Effective Molarity (EM), the physico-chemical parameter expressing the ease of cyclization of a chain. The first three models (A–C) are derived from the revision of previous theories of catenation, that neglect excluded volume effects. A fourth model (D) is obtained from the results of Monte Carlo simulations by Deguchi and co, that can also account for excluded volume effects. Finally, a fifth model (E) is introduced which has the same functional form of models A, B, D, but is parameterized using the available experimental catenation constant.

**On the basis of theories and simulations, the authors propose five models** giving the equilibrium constant *K _{ij}* for the catenation of two ring oligomers, C

Pulsed-laser polymerization (PLP) in conjunction with polymer analysis by size-exclusion chromatography (SEC) is the IUPAC-recommended method for measuring propagation rate coefficients, *k*_{p}, of radical polymerization. Pulse repetition rate, *v*_{rep}, and photoinitiator concentration need to be adjusted to the termination rate of the monomer, preferably via the quantity *β*, the fraction of radicals terminating prior to applying the successive laser pulse. By PREDICI simulation, the prerequisites for successful PLP-SEC work are demonstrated. Slow termination, as with fully ionized monomers, is specifically addressed. Both very high and very low *v*_{rep} are not suitable for accurate *k*_{p} measurements.

**The PLP-SEC method runs into difficulties with radical termination being** too fast or too slow and in case of significant chain transfer and SEC broadening. The suitable selection of pulse repetition rate and photoinitiator concentration is emphasized for slow termination as with ionized monomers.

The orientation of a three-layered silicate particle in uncompatibilized and compatibilized polymer melts is studied under shear flows utilizing dissipative particle dynamics (DPD). Based on trajectories, pair distribution functions are calculated in orthogonal planes. Regardless of the applied flow direction, it is shown that the layers rearrange themselves so that their surfaces would be normal to the velocity gradient direction. The maximum shear stress values fall in numerical uncertainties in uncompatibilized systems while they show a characteristic overshoot in compatibilized counterparts. This overshoot is shown to be a result of (i) the large interfaces between the silicate layers and the matrix due to the exfoliation, and (ii) the increased energy dissipation due to friction at the interface.

**The orientation of a three-layered silicate particle in uncompatibilized** and compatibilized polymer melts is studied under shear flows utilizing dissipative particle dynamics. It is shown that the layers rearrange themselves so that their surfaces would be normal to the velocity gradient direction. The orientation process is found to be more stable in compatibilized systems even at low shear-rates.