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Three novel polymers (P(FHEMA-co-MAAT)s) having redox and photoresponsive moieties were prepared by free radical polymerization. The structures and molecular weights of the synthesized copolymers were characterized by nuclear magnetic resonance (1H NMR) and gel permeation chromatography (GPC) respectively. Thermal properties, optical features and electroactive properties were studied with the help of thermogravimetric (TG), differential thermogravimetric (DTG) analysis, ultraviolet-visible spectroscopy (UV-vis) and cyclic voltammetry (CV). It was seen that synthesized copolymers had excellent redox and photoresponsive properties. These results exhibited that these polymers can be applied further for redox/photo responsive information storage devices.

The Burning rate of a solid propellant predominantly influences its internal ballistic behavior and it has been well known that incorporation of small quantities of certain classes of organic and inorganic substance to a propellant can drastically alter its burning rate characteristics. The inclusion of energetic materials and burning rate catalysts (BRCs) from the metallocene family (e.g., ferrocene (Fc) and 2,2-bis (ethylferrocenyl) propane also known as catocene (Cat)) has been a promising avenue for efficiently increasing the burning rate of propellants. Fc-based materials are dominantly used as burning rate catalysts in solid propellants because of their low volatility, higher compatibility with organic binders, microscopic homogeneities in distribution, broad range of burning rate adjustments, better ignitability and distinct catalytic features. However, in solid composite propellants, Fc-based polymers and derivatives show undesired properties of high migration, that is travelling out from propellant grain to surrounding insulation material on prolong storage, evaporation or sublimation loss during processing and curing as well as phase separation by crystallization in low-temperature applications, limiting their application as BRCs. This article outlines the latest synthetic advancements in the field of Fc-based BRCs, as well as highlighting their catalytic and anti-migration mechanisms.

Understanding segmental dynamics of polymer chains is important to decipher the microscopic behavior in order to modulate the bulk properties of polymers. Study of electron spin resonance (ESR) spectroscopy of polymer chain segments is useful to understand internal dynamics of polymer chains in solution. In this paper, poly(oligoethylene glycol methacrylate-co-2,2,6,6-tetramethyl piperidin-4-yl methacrylate)s, OEG-TMPMs, were synthesized. The synthesized OEG-TMPMs were characterized by nuclear magnetic resonance (NMR) spectroscopy, gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and thermogravimetric (TG) techniques. The TMPM moiety in OEG-TMPMs was oxidized to 2,2,6,6-tetramethyl-1-piperinidyloxy-4-yl methacrylate (TMP) to generate nitroxide radicals. These nitroxide radical-containing OEG-TMPs were analyzed with Fourier transform-infrared (FT-IR) spectroscopy, cyclic voltammetry (CV) and ESR spectroscopy. The effect of side chain length on the segmental mobility of OEG-TMPs was studied. The results showed that the longer pendent chains as in OEG-TMP-4 imparted higher flexibility to the backbone of the polymer and increased rotational freedom of nitroxide radicals as compared to restricted mobility in the case of shorter polymer side chains.

A series of copolymers of poly(2-(methacryloyloxy) ethyl ferrocene carboxylate-co-methacrylic acid)s (P(FHEMA-co-MAA)s) were synthesized as burning rate catalysts (BRCs). Their structures were verified using proton nuclear magnetic resonance (1H NMR) and Fourier transforms infrared (FT-IR) spectroscopy. The electrochemical behavior of P(FHEMA-co-MAA)s was investigated by cyclic voltammetry (CV). The CV results indicated that P(FHEMA-co-MAA)s showed redox behavior. Anti-migration test proved that P(FHEMA-co-MAA)s possesses better anti-migration properties than ferrocene (Fc) and 2, 2-bis (ethylferrocenyl) propane (Catocene). The burning rate (BR) catalytic effect of P(FHEMA-co-MAA)s on thermal decomposition of AP was examined through thermogravimetry (TG) and differential thermogravimetry (DTG). P(FHEMA-co-MAA)s were found to have high catalytic effects in accelerating thermal decomposition of ammonium perchlorate (AP).

Different glucose-responsive nanogels of N-isopropylacrylamide (NIPAM) and 4-(1,6-dioxo-2,5-diaza-7-oxamyl) phenylboronic acid (DDOPBA) were synthesized using dextran-grafted maleic acid (Dex-MA) as a crosslinker. The formed nanogels (P(NIPAM-co-Dex-co-DDOPBA)s) were verified by 1H NMR, TEM, DLS and X-ray photoelectron spectroscopy (XPS). The incorporation of DDOPBA provided a remarkable sensitivity towards glucose in physiological pH due to the existence of electron-withdrawing group in its structure. Similarly, the hydrophilic Dex-MA modulated the temperature-sensitivity near physiological temperature. The nanogels exhibited high insulin loading capacity and encapsulation efficiency and the in vitro release profiles demonstrated a glucose dependant release of the payload at physiological pH and temperature.

Different copolymers (poly(2-(methacryloyloxy) ethyl ferrocene carboxylate-co-methacrylo-4-aminoazobenzene-co-methacrylic acid)s) (P(FHEMA-co-MAZO-co-MAA)s) were synthesized and their different properties were analyzed in this work. Methacrylic acid was introduced as a side group to possibly affect the photostability. The synthesized copolymers were characterized by nuclear magnetic resonance (1H NMR) spectroscopy and gel permeation chromatography (GPC). Thermal studies were performed by thermogravimetric (TG), differential thermogravimetric (DTG) and differential scanning calorimetry (DSC) analysis, which showed that the copolymers were thermally stable under the operating conditions of the information storage devices. Redox studies and photoresponsive studies were performed by CV technique and UV/vis spectroscopy which showed that these copolymers contained good redox and photoresponsive properties. The obtained results paved the way towards the four states information storage of the materials.

Five ferrocene (Fc)-based compounds (HQ-Fcs) were synthesized by the condensation reaction of ferrocenecarbonyl chloride with corresponding hydroquinone derivatives. Nuclear magnetic resonance (1H NMR), and Fourier transform infrared (FT-IR) were used as evidence for the synthesis of HQ-Fcs. The electrochemical properties of HQ-Fcs were investigated by cyclic voltammetry (CV) and suggested that these compounds exhibited redox behavior due to ferrocene groups. The burning rate catalytic effect of HQ-Fcs was examined by Thermogravimetric (TG) and differential Thermogravimetric (DTG) techniques. Thermal analysis results indicated that HQ-Fcs were thermally stable and have better burning rate catalytic effects in accelerating thermal decomposition of AP. Anti-migration behavior of HQ-Fcs in comparison to commonly used 2,2-bis (ethylferrocenyl) propane (catocene) and Fc was evaluated. It was observed that HQ-Fcs delivered excellent anti-migration performances than catocene and Fc.