Molecular “Building Block” and “Side Chain Engineering”: Approach to Synthesis of Multifunctional and Soluble Poly(pyrrole phenylene)sChan, Eddie Wai Chi; Baek, Paul; Tan, Shi Min; Davidson, Samuel J.; Barker, David; Travas‐Sejdic, Jadranka
doi: 10.1002/marc.201800749pmid: 30512205
Here, the synthesis of a novel poly(pyrrole phenylene) (PpyP) that is both modular in ways of functionalization and soluble in organic solvents is reported, and therefore solution processable. This is achieved through the functionalization of the side‐chain substituents in pyrrole phenylene (PyP) repeating units.
t
Butyl acrylate brushes are first grafted through atom transfer radical polymerization from one type of PyP, followed by oxidative chemical co‐polymerization of the grafted PyP with a PyP bearing different side chains—either an azide or a methoxy moiety, resulting in a soluble PpyP where solubility is not dopant‐dependent. Successful post‐polymerization modification through “click” chemistry and post‐polymerization processing via electrospinning are also demonstrated. Additionally, performed computational calculations indicate planarity of the novel polyrrole phenylene monomers and ionisation potentials that favor α–α bond formation during their polymerization.
Polyurethane Coatings Based on Renewable White Dextrins and Isocyanate TrimersKonieczny, Jakob; Loos, Katja
doi: 10.1002/marc.201800874pmid: 30730069
The polyurethane industry is strongly dependent on fossil‐based polyols and polyisocyanates. Developing novel sustainable polyols from valuable biobased building blocks is a first step toward strong and durable development. The synthesis and properties of PU films based on pristine and acylated white dextrins (AVEDEX W80) as polyol and an aliphatic, low‐viscosity, solvent‐free triisocyanate based on hexamethylene diisocyanate (trimer—Desmodur N3300) as crosslinker is reported. After optimizing several conditions, such as the reaction time, reaction temperature, amount of solvent, isocyanate index, and amount per surface area, it is possible to obtain smooth PU films with good thermal properties.
Grafting from Starch Nanoparticles with Synthetic Polymers via Nitroxide‐Mediated PolymerizationCazotti, Jaime C.; Fritz, Alexander T.; Garcia‐Valdez, Omar; Smeets, Niels M. B.; Dubé, Marc A.; Cunningham, Michael F.
doi: 10.1002/marc.201800834pmid: 30663157
Nitroxide‐mediated polymerization (NMP) is employed to graft synthetic polymers from polysaccharides. This work demonstrates the first successful polymer grafting from starch nanoparticles (SNPs) via NMP. To graft synthetic polymers from the SNPs' surface, the SNPs are first functionalized with 4‐vinylbenzyl chloride prior to reaction with BlocBuilder MA yielding a macroinitiator. Methyl methacrylate with styrene, acrylic acid, or methyl acrylate are then grafted from the SNPs. The polymerizations exhibited linear reaction kinetics, indicating that they are well controlled. Thermal gravimetric analysis and spectroscopic techniques confirmed the synthesis of the precursors materials and the success of the grafting from polymerizations. The incorporation of hydrophobic synthetic polymers on hydrophilic SNPs yields new hybrid materials that could find use in several industrial applications including paper coatings, adhesives, and paints.
Using Synergistic Multiple Dynamic Bonds to Construct Polymers with Engineered PropertiesJiang, Zhen; Bhaskaran, Ayana; Aitken, Heather M.; Shackleford, India C. G.; Connal, Luke A.
doi: 10.1002/marc.201900038pmid: 30977952
Dynamic bonds have achieved significant attention for their ability to impart fascinating properties to polymeric materials, such as high mechanical strength, self‐healing, shape memory, 3D printability, and conductivity. Incorporating multiple dynamic bonds into polymer systems affords an attractive and efficient approach to endow multiple functionalities. This mini‐review focuses on the use of complementary dynamic interactions to control the properties of soft materials. Owing to the diversity in dynamic chemistries that can be explored, the scope of this article is restricted to polymers and does not include colloids, amphiphiles, liquid crystals, or biological soft matter.
Aqueous Synthesis of Multi‐Carbon Dot Cross‐Linked Polyethyleneimine Particles with Enhanced Photoluminescent PropertiesYao, Yuan; Niu, Dechao; Lee, Cheng Hao; Li, Yongsheng; Li, Pei
doi: 10.1002/marc.201800869pmid: 30828932
Heavy‐metal‐free fluorescent nanoparticles with high photostability and low toxicity are highly desirable as imaging probes for biological applications. Here, a novel synthetic strategy to prepare ultrabright multi‐carbon dot cross‐linked PEI particles, namely CDs@PEI, through self‐assembly of hydrophobically modified PEI and in situ generations of carbon dots within residual monomer‐swollen micelles is reported. The resulting particles consist of numerous carbon dots, which are individually and homogeneously embedded within the PEI network, and have an average hydrodynamic diameter of approximately 100 nm with ζ‐potential above +35 mV. The CDs@PEI particles possess the synergistic effect of photoluminescent carbon dot and crosslink‐enhanced emission of PEI, giving the particles superior optical properties such as high fluorescence quantum yield (up to 66%) in the aqueous system, excitation‐dependent emission phenomenon, stable fluorescence in a wide pH range, and resistance to photobleaching.
ATRP of N‐Hydroxyethyl Acrylamide in the Presence of Lewis Acids: Control of Tacticity, Molecular Weight, and ArchitectureSun, Yue; Fu, Liye; Olszewski, Mateusz; Matyjaszewski, Krzysztof
doi: 10.1002/marc.201800877pmid: 30650236
Good control of tacticity, molecular weight, and architecture is attained via atom transfer radical polymerization (ATRP) of N‐hydroxyethyl acrylamide (HEAA), in a one‐pot process in the presence of Y(OTf)3. The effect of temperature, ratio of [Y(OTf)3]/[HEAA], and ATRP procedure on the tacticity and degree of control over the polymerization is investigated in detail. Under optimal conditions, using photo ATRP and 15% Y(OTf)3, the content of meso dyads (m) can be increased from 42% to 80% in a homopolymer with a dispersity D = 1.22. Well‐defined stereoblock copolymers, atactic‐
b
‐isotactic poly(HEAA), with D = 1.27, are obtained by adding Y(OTf)3 at a specific conversion, initially started without Y(OTf)3.