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Tandem mass spectrometry (MS 2 ) has been employed to elucidate the topology and branching architecture of star-branched polyethers. The polymers were ionized by matrix-assisted laser desorption/ionization (MALDI) to positive ions and dissociated after leaving the ion source via laser-induced fragmentation. The bond scissions caused under MALDI-MS 2 conditions occur preferentially near the core-branch joining points due to energetically favorable homolytic and heterolytic bond cleavages near the core and release of steric strain and/or reduction of crowding. This unique fragmentation mode detaches complete arms from the core generating fragment ion series at the expected molecular weight of each branch. The number of fragment ion distributions observed combined with their mass-to-charge ratios permit conclusive determination of the degree of branching and the corresponding branch lengths, as demonstrated for differently branched homo- and mikto-arm polyether stars synthesized via azide-alkyne click chemistry. The results of this study underscore the utility of MS 2 for the characterization of branching architecture and branch lengths of (co) polymers with two or more linear chains attached to a functionalized central core.

The purpose of this study is to describe some of the latest advances in using hydrogels for cancer melanoma therapy. Hydrogel formulations of polymeric material from natural or synthetic sources combined with therapeutic agents have gained great attention in the recent years for treating various maladies. These formulations can be categorized according to the strategies that induce cancer cell death in melanoma. First of all, we should note that these formulations can only play a supporting role that releases bioactive agents against cancer cells rather than the main role. This strategy involves delivering the drug via transdermal pathways, resulting in the death of cancerous cells. Another strategy utilizes magnetic gel composites to combat melanoma via hyperthermia therapy. This review discusses both transdermal and hyperthermia therapies and the recent advances that have occurred in the field.

Polymer-ceramic nanocomposites have been thoroughly investigated previously for high energy storage devices. However, the increase in performance of these nanocomposites has proven to be significantly lower than predicted values. Through surface functionalization of high dielectric constant nanoparticles (NP), the flaws that reduce composite performance can be eliminated to form high energy density composite materials. Functionalization methods utilize high throughput printing and curing techniques (i.e., inkjet printing and xenon flash lamp curing) that are crucial for rapid adoption into industrial production. (Ba,Ca) (Zr,Ti)O3 NPs (50 nm) are synthesized through the solvothermal method and functionalized with alkene terminated methoxysilanes. A thiol-ene monomer ink system, PTD3 [pentaerythritol tetrakis (3-mercaptopropionate) (PEMP, P), 1,3-Diisopropenylbenzene (DPB, D), 2,4,6-Triallyloxy-1,3,5-triazine (TOTZ, T)], is used as a high breakdown polymer matrix. Neat polymer, alkene terminated NP-polymer composites, and hydrophilic, TBAOH functionalized NP-polymer composites were spin coated onto both copper laminated glass slides and printed onto copper substrates in 1 cm(2) patterns for testing. Alkene functionalized NPs increased the breakdown strength by ∼38% compared to the nonfunctionalized NPs. Functionalized NPs increased both the breakdown strength and dielectric constant compared to the neat polymer, increasing the energy density nearly 3-fold from 13.3 to 36.1 J·cm(-3).

End groups play a critical role in macromolecular coupling reactions for building complex polymer architectures, yet their identity and purity can be difficult to ascertain using traditional analytical technique. Recent advances in mass spectrometry techniques have made matrix-assisted laser desorption/ionization time-of-fight (MALDI-TOF) mass spectrometry a rapid and powerful tool for providing detailed information about the identity and purity of homopolymer end groups. In this work, MALDI-TOF mass spectrometry was used to study end groups of linear polyethylene glycols. In particular, the identifications of alcohol, amine and thiol end groups are investigated because these nucleophilic moieties are among the most common within biological and synthetic macromolecules. Through comparative characterization of alcohol, amine, and thiol end groups, the exact identification of these end groups could be confirmed by selective and quantitative modification. The precision of this technique enables the unambiguous differentiation of primary amino groups relative to hydroxyl groups, which differ by only 1 mass unit. In addition, the quantitative conversion of various polyethylene glycol end groups using highly efficient coupling reactions such as the thiol-ene and azide-alkyne click reactions can be confirmed using MALDI-TOF mass spectrometry., (Copyright © 2014 Elsevier B.V. All rights reserved.)

High purity homo-arm and mikto-arm poly(ethylene glycol) (PEG) stars are successfully prepared by the combination of epoxide ring-openings and azide-alkyne click reactions. First, monohydroxy-PEG was modified via epoxide chemistry to bear one hydroxyl and one azide functionality at the same end. An alkyne-functionalized PEG chain was then coupled to the azide. Subsequently, the remaining hydroxyl could be reactivated to an azide again and again to enable stepwise addition of alkyne-functionalized polymer arms. The use of efficient reactions for this iterative route provides star polymers with an exact number of arms, and a tailorable degree of polymerization for each arm. Detailed characterization confirms the high purity of multi-arm polyethylene glycol products., (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)