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Hydrogels based on reversible covalent bonds represent an attractive topic for research at both academic and industrial level. While the concept of reversible covalent bonds dates back a few decades, novel developments continue to appear in the general research area of gels and especially hydrogels. The reversible character of the bonds, when translated at the general level of the polymeric network, allows reversible interaction with substrates as well as responsiveness to variety of external stimuli (e.g., self-healing). These represent crucial characteristics in applications such as drug delivery and, more generally, in the biomedical world. Furthermore, the several possible choices that can be made in terms of reversible interactions generate an almost endless number of possibilities in terms of final product structure and properties. In the present work, we aim at reviewing the latest developments in this field (i.e., the last five years) by focusing on the chemistry of the systems at hand. As such, this should allow molecular designers to develop a toolbox for the synthesis of new systems with tailored properties for a given application.

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An in-depth study on the effect of process conditions (pressure, temperature and type of catalyst) on the acetylation of starch with acetic anhydride in pressurised carbon dioxide is described. A total of 22 experiments were performed and the experimental data were analysed using non-linear multivariable regression. The highest degree of substitution (DS) value (0.46) was obtained using K 2 CO 3 as the catalyst at 908C, 15 MPa pressure, and a catalyst to starch ratio of 0.5 mol/mol anhydroglucose units (AGUs). Important product properties of the acetylated starch prepared in CO 2 like viscosity in water and relevant thermal properties were determined and compared with typical products prepared in an aqueous system.

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The solubility of CO2 in native potato starch (NPS) and potato starch acetate (SA) at two different temperatures (50°C and 120°C) and various pressures (up to 25 MPa) was determined using a magnetic suspension balance. Within the experimental window, a maximum solubility of 31 mg CO2/gsample for NPS and 79.4 mg CO2/gsample for SA was obtained. The CO2 sorption behavior is highly depending on the temperature and pressure. The solubility data were modeled with the Sanchez Lacombe equation of state (S‐L EOS). The swelling (Sw) values, as predicted using the S‐L EOS, were relatively small and a maximum value of 6.1% was obtained for SA at 25 MPa and 120°C. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers

08%. Kelarutan (6,[9][10][11] dan kekuatan mengembang (9,88-11,17 g/g) pada produk pati termodifikasi mengalami peningkatan dibandingkan dengan pati alaminya (kelarutan = 6,06%-b/b, kekuatan mengembang = 8,05 g/g). Fosforilasi juga terbukti dapat meningkatkan viskositas puncak, kejernihan pasta, dan daya serap air/minyak pada produk yang diperoleh.