Poly(N-isopropylacrylamide): experiment, theory and application

Temperature-sensitive aqueous microgels.

Jets, ie collimated streams of matter, occur from the microscale up to the large-scale structure of the universe Our focus will be mostly on surface tension effects, which result from the cohesive properties of liquids Paradoxically, cohesive forces promote the breakup of jets, widely encountered in nature, technology and basic science, for example in nuclear fission, DNA sampling, medical diagnostics, sprays, agricultural irrigation and jet engine technology Liquid jets thus serve as a paradigm for free-surface motion, hydrodynamic instability and singularity formation leading to drop breakup In addition to their practical usefulness, jets are an ideal probe for liquid properties, such as surface tension, viscosity or non-Newtonian rheology They also arise from the last but one topology change of liquid masses bursting into sprays Jet dynamics are sensitive to the turbulent or thermal excitation of the fluid, as well as to the surrounding gas or fluid medium The aim of this review is to provide a unified description of the fundamental and the technological aspects of these subjects

Physics of liquid jets

Polymers have played an integral role in the advancement of drug delivery technology by providing controlled release of therapeutic agents in constant doses over long periods, cyclic dosage, and tunable release of both hydrophilic and hydrophobic drugs. From early beginnings using off-the-shelf materials, the field has grown tremendously, driven in part by the innovations of chemical engineers. Modern advances in drug delivery are now predicated upon the rational design of polymers tailored for specific cargo and engineered to exert distinct biological functions. In this review, we highlight the fundamental drug delivery systems and their mathematical foundations and discuss the physiological barriers to drug delivery. We review the origins and applications of stimuli-responsive polymer systems and polymer therapeutics such as polymer-protein and polymer-drug conjugates. The latest developments in polymers capable of molecular recognition or directing intracellular delivery are surveyed to illustrate areas of research advancing the frontiers of drug delivery.

Polymers for Drug Delivery Systems

Interest in thermoresponsive polymers has steadily grown over many decades, and a great deal of work has been dedicated to developing temperature sensitive macromolecules that can be crafted into new smart materials. However, the overwhelming majority of previously reported temperature-responsive polymers are based on poly(N-isopropylacrylamide) (PNIPAM), despite the fact that a wide range of other thermoresponsive polymers have demonstrated similar promise for the preparation of adaptive materials. Herein, we aim to highlight recent results that involve thermoresponsive systems that have not yet been as fully considered. Many of these (co)polymers represent clear opportunities for advancements in emerging biomedical and materials fields due to their increased biocompatibility and tuneable response. By highlighting recent examples of newly developed thermoresponsive polymer systems, we hope to promote the development of new generations of smart materials.

New directions in thermoresponsive polymers.

Etude par DSC de la transition de type thermoretrait de gels aqueux de N-isopropylamide (NIPA) de solutions de poly(NIPA) et de PVME. Comparaison des temperatures de transition des gels et des solutions obtenues par DSC avec les valeurs obtenues par mesure du gonflement des gels et par mesure des points de trouble des solutions. Interpretation des resultats a l'aide du concept d'interaction hydrophobe. Influence d'additifs de faible masse sur les temperatures de transition

Thermal analysis of the volume phase transition with N-isopropylacrylamide gels

Les polymeres du N-propyl et du N-isopropyl acrylamide en solution aqueuse presentent un comportement de type LCST et les hydrogels correspondants presentent une transition de phase, contrairement au poly(N-cyclopropyl acrylamide)

Phase Transition of N-Substituted Acrylamide Gels

Les mesures des donnees d'equilibre de phases sont effectuees a 313.4 et 333.4 K a l'aide d'un nouvel appareil statique. L'appareillage est presente

Isothermal vapor-liquid equilibrium data for binary systems at high pressures: carbon dioxide-methanol, carbon dioxide-ethanol, carbon dioxide-1-propanol, methane-ethanol, methane-1-propanol, ethane-ethanol, and ethane-1-propanol systems

Effect of Additives on Phase Transition of N-Isopropylacrylamide Gels

The effect of scale on the breakup process in liquid-liquid agitated tanks was investigated. Transient drop size distributions in the breakup process were measured in geometrically similar mixing vessels at equal power input per unit mass, which was taken as a scale-up criterion under the assumption of isotropic turbulence for the flow around drops. The distributions in each vessel, however, did not undergo the same variation with time and the condition of equal power input per unit mass was found to be inappropriate as a scale-up criterion for the breakup process. The experimental result was explained from direct observation of breakups in the mixing vessels by high-speed cine-photography. The observations made it clear that breakups occurred not only in the isotropic turbulent region but also in the nonisotropic turbulent region. A new model for the breakup process was proposed which considers breakups in both regions. This model successfully predicted the transient drop size distributions.

Shozaburo Saito

Papers

Thermal analysis of the volume phase transition with N-isopropylacrylamide gels

Phase Transition of N-Substituted Acrylamide Gels

Isothermal vapor-liquid equilibrium data for binary systems at high pressures: carbon dioxide-methanol, carbon dioxide-ethanol, carbon dioxide-1-propanol, methane-ethanol, methane-1-propanol, ethane-ethanol, and ethane-1-propanol systems

Effect of Additives on Phase Transition of N-Isopropylacrylamide Gels

Scale effect on breakup process in liquid-liquid agitated tanks