Modeling and characterization of the morphology of multiphase polymeric nanoparticles

Multiphase polymeric nanoparticles that synergistically combine the properties of their constituents present enhanced properties and display new functionalities. Therefore, they are used in a wide range of applications including anticorrosive, superhydrophobic and anti-molding coatings; switchable adhesives; photoswitchable fluorescent particles; energy storage; gene and drug delivery; anticounterfeiting and LEDs. Although it is recognized that application properties strongly depend on the morphology of the nanoparticles, there is a surprising lack of progress towards the knowledge-based synthesis of these materials with well controlled morphologies. There are two main reasons for this. Firstly, the difficulties associated to the accurate characterization of the morphology of the polymeric nanoparticles, and secondly, the lack of quantitative understanding of the processes controlling the morphology. Please click Additional Files below to see the full abstrac

Surfactant-free miniemulsion polymerization ofn-BA/S stabilized by NaMMT : films with improved water resistance

The use of sodium montmorillonite clay as a stabilizer in the surfactant-free emulsion polymerization of n-butyl acrylate/styrene (n-BA/S) was assessed. It was shown that the use of the clay alone did not yield the desired armored latex particles. A functional comonomer, that is, a phosphate ester of poly(ethylene glycol) monomethacrylate, was used to improve the interaction between the polymer and clay, thus allowing for the clay platelets to adhere to the surface of the polymer particles. The morphology of the films obtained for these two different scenarios was similar and resembled a honeycomb structure. However, their water-resistance properties differed drastically. The water absorption and water vapor permeation rate were much lower in the hybrid n-BA/S/clay films in the presence of the functional monomer than in the films obtained without the functional monomer

Phase behavior of side-chain liquid-crystalline polymers containing biphenyl mesogens with different spacer lengths synthesized via miniemulsion polymerization

The synthesis of a series of methacrylate side-chain liquid crystal polymers (SCLCPs) bearing biphenyl mesogen with different spacer lengths and a fixed tail, poly[ethyl 4′-((n-(methacryloyloxy)alkyl)oxy)-[1,1′-biphenyl]-4-carboxylate]s (n-PMLCM, n = 3, 4, 5, 6), in aqueous media by free radical miniemulsion polymerization is described. This method offers the advantage of producing high molar masses (>105 Da) and full monomer conversion, not possible to achieve with conventional routes (solution polymerization). The resulting n-PMLCMs proved to have high thermal stability. The phase behaviors of the polymers were investigated by a combination of techniques including differential scanning calorimetry, polarized light microscopy, and small and wide angle X-ray scattering. The results show mesomorphic liquid crystalline behavior with a monolayer structure where the side-groups on both sides of the backbone would be interpenetrated. The liquid crystal phase transition of n-PMLCM follows the sequence smectic E (smectic E or smectic C for 4-PMLCM) ↔ smectic A ↔ isotropic liquid. The transition temperatures and the associated entropy changes exhibit a distinct odd–even effect as the length and parity of the spacer are varied, with the odd members exhibiting the higher values. The high molar masses achievable using miniemulsion polymerization translate into a more perfect and stable ordering, characterized by larger lamellar domains and higher transition temperatures, than in low molar mass SCLCPs. Compared to polymeric liquid crystals with similar mesogens but shorter tails, we found that longer tails facilitate the ordering of the mesogens and allow more efficient packing around the backbones, imparting a high stability to the smectic phases formed.The financial support from the Industrial Liaison Program on Polymerization in Dispersed Media (Akzo Nobel, Allnex, Arkema, BASF, Foresa, Nuplex Resin, Solvay, Stahl, Synthomer, Vinavil, Wacker) is gratefully acknowledged. A. A. and A. I. acknowledge financial support from the projects MAT2015-63704-P (Spanish-MINECO) and IT-654-13 (Basque Government). J. R. L. acknowledges financial support from the project CTQ2014-59016-R (MINECO).Peer reviewe

Acrylic-based composite latexes containing nano-sized liquid crystalline domains

Two-scale multicomposite (meth)acrylate latexes containing nano-sized liquid crystalline domains were synthesized in a two step (mini)emulsion polymerization using a series of methacrylate side chain liquid crystalline monomers and mixture of short chain (meth)acrylates. Detailed characterization of the composite films obtained from the latexes using a combination of DSC, TEM, polarized light microscopy, SAXS and WAXS showed that the liquid crystalline polymers had a layered structure with a 2D-organization that was not perturbed by the amorphous polymer, which on the other hand was partially intercalated between layers. This leads to a two-scale composite with enhanced mechanical properties and higher number of degrees of freedom to fine tune the mechanical properties. The effect of liquid crystalline domains on barrier properties as well as on the water resistance of the films formed from these latexes was also investigated. The persistence of crystalline order of the liquid crystalline polymer phase up to very high temperatures leads to materials with a very broad temperature range of application, improving significantly the performance with respect to other routes based on incorporation of crystalline domains via copolymerization with comb-like monomers.Financial support of the Industrial Liaison Program on Polymerization in Dispersed Media (Akzo Nobel, Allnex, Arkema, BASF, Foresa, Nuplex Resin, Solvay, Stahl, Synthomer, Vinavil, Wacker) is gratefully acknowledged. A. A. and A. I. acknowledge financial support by the Spanish Ministry 'Ministerio de Economia y Competitividad', code: MAT2015-63704-P (MINECO/FEDER, UE) and by the Eusko Jaurlaritza, code: IT-654-13. J. R. L. acknowledges financial support from the Spanish Ministry ’Ministerio de Economia y Competitividad’, code: CTQ2014-59016-R (MINECO).Peer Reviewe

Insights into the network structure of cross-linked polymers synthesized via miniemulsion nitroxide-mediated radical polymerization

The effect of reversible-deactivation radical polymerization on the structure of the network formed by copolymerization of mono- and divinyl monomers is studied. The nitroxide-mediated radical copolymerization (NMP) of butyl methacrylate and ethylene glycol dimethacrylate, initiated with the alkoxyamine 3-(((2-cyanopropan-2-yl)oxy)cyclohexylamino)-2,2-dimethyl-3-phenylpropanenitrile (Dispolreg 007) in an aqueous miniemulsion was used as a case study. Combination of asymmetric-flow field-flow fractionation and small-angle X-ray scattering clearly showed that NMP led to a more homogeneous network structure formed by regions of relatively open networks connected with short polymer chain segments, whereas that of the polymer formed by free radical polymerization consists of densely cross-linked regions linked by long polymer chain portions.Diputacion Foral de Gipuzkoa, University of Basque Country UPV/EHU (UFI 11/56), Basque Government (Grants GVIT373-10 and GVIT654-13), and MINECO (Grants CTQ2016-80886-R, CTQ2017-87841-R, and MAT2015-63704-P) are gratefully acknowledged for their financial support. N.B. acknowledges the financial support obtained through the postdoctoral fellowship Juan de la Cierva - Incorporacion (Grant IJCI-2016-28442) from the Ministry of Economy and Competitiveness of Spain.Peer reviewe