Diagnosing the role of the state for local collective action : types of action situations and policy instruments

Unidad de excelencia María de Maeztu MdM-2015-0552This paper presents a diagnostic approach to the role and capacity of governments to facilitate local collective action and alleviate environmental problems. The paper adds to a nascent scholarship aiming to conciliate theories on "governance by government" and "governance by self-organization". We adopt two premises for that purpose: (1) policy instruments shall be tailored to the strategic nature of local resource management decisions; and (2) such nature is not static and can be modified via governmental policies. We first build on the Institutional Analysis and Development (IAD) framework to characterize the decision-making situations that local resource users face and the local rules that shape said situations. Then, based on common pool resource (CPR) and policy instrument choice theory, we identify four mechanisms through which different policy instruments can facilitate local collective action (change in payoffs and their perception, reduction of transaction costs, reduction of uncertainty, and normative consonance). This analytical approach is then applied to four illustrative cases of water management in Germany, France, Greece and Spain. As shown, local resource users are embedded in not one but many overlapping decision-making situations. In this context, the promotion of collective action is rarely accomplished via a single policy instrument or mechanism but via bundles of them. Also, the paper illustrates the importance of understanding how governmental policies modify the structure of rules and incentives that affect local resource users, potentially facilitating local collective action and the solution of environmental problems

Effect of Polymer Molecular Weight and Solution pH on the Surface Properties of Sodium Dodecylsulfate-Poly(Ethyleneimine) Mixtures

The effect of polymer molecular weight and solution pH on the surface properties of the anionic surfactant sodium dodecylsulfate, SDS, and a range of small linear poly­(ethyleneimine), PEI, polyelectrolytes of different molecular weights has been studied by surface tension, ST, and neutron reflectivity, NR, at the air–solution interface. The strong SDS–PEI interaction gives rise to a complex pattern of ST behavior which depends significantly on solution pH and PEI molecular weight. The ST data correlate broadly with the more direct determination of the surface adsorption and surface structure obtained using NR. At pH 3, 7, and 10, the strong SDS–PEI interaction results in a pronounced SDS adsorption at relatively low SDS and PEI concentrations, and is largely independent of pH and PEI molecular weight (for PEI molecular weights on the order of 320, 640, and 2000 Da). At pH 7 and 10, there are combinations of SDS and PEI concentrations for which surface multilayer structures form. For the PEI molecular weights of 320 and 640 Da, these surface multilayer structures are most well-developed at pH 10 and less so at pH 7. At the molecular weight of 2000 Da, they are poorly developed at both pH 7 and 10. This evolution in the surface structure with molecular weight is consistent with previous studies, where for a molecular weight of 25 000 Da no multilayer structures were observed for the linear PEI. The results show the importance with increasing polymer molecular weight of the entropic contribution due to the polymer flexibility in control of the surface multilayer formation

Effect of Architecture on the Formation of Surface Multilayer Structures at the Air–Solution Interface from Mixtures of Surfactant with Small Poly(ethyleneimine)s

The impact of ethyleneimine architecture on the adsorption behavior of mixtures of small poly­(ethyleneimines) and oligoethyleneimines (OEIs) with the anionic surfactant sodium dodecylsulfate (SDS) at the air–solution interface has been studied by surface tension (ST) and neutron reflectivity (NR). The strong surface interaction between OEI and SDS gives rise to complex surface tension behavior that has a pronounced pH dependence. The NR data provide more direct access to the surface structure and show that the patterns of ST behavior are correlated with substantial OEI/SDS adsorption and the spontaneous formation of surface multilayer structures. The regions of surface multilayer formation depend upon SDS and OEI concentrations, on the solution pH, and on the OEI architecture, linear or branched. For the linear OEIs (octaethyleneimine, linear poly­(ethyleneimine) or LPEI₈, and decaethyleneimine, LPEI₁₀) with SDS, surface multilayer formation occurs over a range of OEI and SDS concentrations at pH 7 and to a much lesser extent at pH 10, whereas at pH 3 only monolayer adsorption occurs. In contrast, for branched OEIs BPEI₈ and BPEI₁₀ surface multilayer formation occurs over a wide range of OEI and SDS concentrations at pH 3 and 7, and at pH 10, the adsorption is mainly in the form of a monolayer. The results provide important insight into how the OEI architecture and pH can be used to control and manipulate the nature of the OEI/surfactant adsorption

Temperature Resistant Binary SLES/Nonionic Surfactant Mixtures at the Air/Water Interface

Surface compositions of adsorbed monolayers at the air/water interface, formed from binary surfactant mixtures in equilibrium, have been studied using neutron reflectivity at three discrete temperatures: 10, 25, and 40 °C. The binary compositions studied are sodium lauryl dodecyl ether sulfate (SLES EO3)/C12E<i>n</i>, where <i>n</i> = 6 and 8, at a fixed concentration of 2 mM with and without the addition of 0.1 M NaCl. Without NaCl, the nonionic surfactant dominates at the interface and nonideal mixing behavior is observed. This is modeled using the pseudophase approximation with a quadratic expansion of the free energy of mixing. The addition of 0.1 M NaCl screens the charge interaction between the surfactants and drives the surface composition of each system closer to that of the bulk composition. However, model fits to both the micelles and surface layers suggest that nonideal mixing is still taking place, although it is difficult to establish the extent of nonideality due to the limited data quality. The effect of temperature changes on the surface adsorption and composition of the surfactant mixtures is minimal and within error, with and without NaCl, but the critical micelle concentrations are significantly affected. This indicates the dominant influence of steric hindrances and surfactant charge interactions in determining interfacial behavior for these surfactants, relative to the temperature changes. The study also highlights the delicate effect of a relatively small change in the number of EO groups on mixing behavior

Impact of Electrolyte on Adsorption at the Air–Water Interface for Ternary Surfactant Mixtures above the Critical Micelle Concentration

The composition of the air–water adsorbed layer of the ternary surfactant mixture, octaethylene monododecyl ether, C₁₂E₈, sodium dodecyl 6-benzenesulfonate, LAS, and sodium dioxyethylene glycol monododecyl sulfate, SLES, and of each of the binary mixtures, with varying amounts of electrolyte, has been studied by neutron reflectivity. The measurements were made above the mixed critical micelle concentration. In the absence of electrolyte adsorption is dominated by the nonionic component C₁₂E₈ but addition of electrolyte gradually changes this so that SLES and LAS dominate at higher electrolyte concentrations. The composition of the adsorbed layer in both binary and ternary mixtures can be quantitatively described using the pseudo–phase approximation with quadratic and cubic interactions in the excess free energy of mixing (<i>G</i>_E) at both the surface and in the micelles. A single set of parameters fits all the experimental data. A similar analysis is effective for a mixture in which SDS replaces SLES. Addition of electrolyte weakens the synergistic SLES–C₁₂E₈ and LAS–C₁₂E₈ interactions, consistent with them being dominated by electrostatic interactions. The SLES–LAS (and SDS–LAS) interaction is moderately strong at the surface and is little affected by addition of electrolyte, suggesting that it is controlled by structural or packing factors. Most of the significant interactions in the mixtures are unsymmetrical with respect to composition, with the minimum in <i>G</i>_E at the 1:2 or 2:1 composition. There is a small structural contribution to the LAS-C₁₂E₈ interaction that leads to a minimum intermediate in composition between 1:2 and 1:1 (LAS:C₁₂E₈) and to a significant residual <i>G</i>_<i>E</i> in strong electrolyte

Surface Adsorption in Ternary Surfactant Mixtures above the Critical Micelle Concentration: Effects of Asymmetry on the Composition Dependence of the Excess Free Energy

The composition of the adsorbed layer of a ternary surfactant mixture at the air–water interface has been studied by neutron reflectivity. The adsorption of the ternary mixture of octaethylene monododecyl ether (C₁₂E₈) sodium dodecyl 6-benzene sulfonate (LAS), and sodium dioxyethylene glycol monododecyl sulfate (SLES), as well as each of the binary mixtures, at solution concentrations greater than the mixed critical micelle concentration is highly nonideal. In the ternary mixture, the surface adsorption is dominated by C₁₂E₈ and LAS, and there is little SLES at the interface. The departure from ideality in the binary mixtures can be quantitatively described by applying the pseudophase approximation with quadratic and cubic terms in the excess free energy of mixing (<i>G</i>_E) both at the surface and in the micelles. The same parameters that describe the binary interactions give a quantitative fit to the adsorbed fractions in the ternary mixture over a wide range of composition. A similar analysis is effective for the mixture containing sodium dodecyl sulfate instead of SLES. Of the set of six <i>G</i>_E required to fit the ternary data, one is ideal (SLES–LAS) and three, LAS–C₁₂E₈ (micelle) and C₁₂E₈–SLES (micelle and surface), have minima occurring at a composition (mole fraction) of the anionic species of 1/3

D. Jose Bernat Sans : de Dual Ibérica de Rubí :

Primer pla de Jose Bernat San

Adsorption at Air–Water and Oil–Water Interfaces and Self-Assembly in Aqueous Solution of Ethoxylated Polysorbate Nonionic Surfactants

The Tween nonionic surfactants are ethoxylated sorbitan esters, which have 20 ethylene oxide groups attached to the sorbitan headgroup and a single alkyl chain, lauryl, palmityl, stearyl, or oleyl. They are an important class of surfactants that are extensively used in emulsion and foam stabilization and in applications associated with foods, cosmetics and pharmaceuticals. A range of ethoxylated polysorbate surfactants, with differing degrees of ethoxylation from 3 to 50 ethylene oxide groups, have been synthesized and characterized by neutron reflection, small-angle neutron scattering, and surface tension. In conjunction with different alkyl chain groups, this provides the opportunity to modify their surface properties, their self-assembly in solution, and their interaction with macromolecules, such as proteins. Adsorption at the air–water and oil–water interfaces and solution self-assembly of the range of ethoxylated polysorbate surfactants synthesized are presented and discussed

Structural Features of Reconstituted Cuticular Wax Films upon Interaction with Nonionic Surfactant C₁₂E₆

The interaction of nonionic surfactant hexaethylene glycol monododecyl ether (C₁₂E₆) with a reconstituted cuticular wheat wax film has been investigated by spectroscopic ellipsometry and neutron reflection (NR) to help understand the role of the leaf wax barrier during pesticide uptake, focusing on the mimicry of the actions adjuvants impose on the physical integrity and transport of the cuticular wax films against surfactant concentration. As the C₁₂E₆ concentration was increased up to the critical micelle concentration (CMC = 0.067 mM), an increasing amount of surfactant mass was deposited onto the wax film. Alongside surface adsorption, C₁₂E₆ was also observed to penetrate the wax film, which is evident from the NR measurements using fully protonated and chain-deuterated surfactants. Furthermore, surfactant action upon the model wax film was found to be physically reversible below the CMC, as water rinsing could readily remove the adsorbed surfactant, leaving the wax film in its original state. Above the CMC, the detergency action of the surfactant became dominant, and a significant proportion of the wax film was removed, causing structural damage. The results thus reveal that both water and C₁₂E₆ could easily penetrate the wax film throughout the concentration range measured, indicating a clear pathway for the transport of active ingredients while the removal of the wax components above the CMC must have enhanced the transport process. As the partial removal of the wax film could also expose the underlying cutaneous substrate to the environment and undermine the plant’s health, this study has a broad implication to the roles of surfactants in crop care

Surface Modification of Polyethylene with Multi-End-Functional Polyethylene Additives

We have prepared and characterized a series of multifluorocarbon end-functional polyethylene additives, which when blended with polyethylene matrices increase surface hydrophobicity and lipophobicity. Water contact angles of >112° were observed on spin-cast blended film surfaces containing less than 1% fluorocarbon in the bulk, compared to ∼98° in the absence of any additive. Crystallinity in these films gives rise to surface roughness that is an order of magnitude greater than is typical for amorphous spin-cast films but is too little to give rise to superhydrophobicity. X-ray photoelectron spectroscopy (XPS) confirms the enrichment of the multifluorocarbon additives at the air surface by up to 80 times the bulk concentration. Ion beam analysis was used to quantify the surface excess of the additives as a function of composition, functionality, and molecular weight of either blend component. In some cases, an excess of the additives was also found at the substrate interface, indicating phase separation into self-stratified layers. The combination of neutron reflectometry and ion beam analysis allowed the surface excess to be quantified above and below the melting point of the blended films. In these films, where the melting temperatures of the additive and matrix components are relatively similar (within 15 °C), the surface excess is almost independent of whether the blended film is semicrystalline or molten, suggesting that the additive undergoes cocrystallization with the matrix when the blended films are allowed to cool below the melting point