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Polymeric Surfactants
Published in E. Desmond Goddard, James V. Gruber, Principles of Polymer Science and Technology in Cosmetics and Personal Care, 1999
E. Desmond Goddard, James V. Gruber
An alternative (and perhaps more efficient) polymeric surfactant is the amphipathic graft copolymer consisting of a polymeric backbone B (polystyrene or polymethylmethacrylate) and several A chains (“teeth”) such as polyethylene oxide. The graft copolymer is referred to as a “comb” stabilizer—the polymer forms a “brush” at the solid/liquid interface. The copolymer is usually prepared by grafting a macromonomer such as methoxy polyethylene oxide methacrylate with polymethyl methacrylate. In most cases, some polymethacrylic acid is incorporated with the polymethylmethacrylate backbone: this leads to reduction of the glass transition of the backbone, which makes the chain more flexible for adsorption at the S/L interface. Typical commercially available graft copolymers are Atlox 4913 and Hypermer CG-6 (ICI).
Understanding the basis of medical use of poly-lactide-based resorbable polymers and composites – a review of the clinical and metabolic impact
Published in Drug Metabolism Reviews, 2019
Sergiu Vacaras, Mihaela Baciut, Ondine Lucaciu, Cristian Dinu, Grigore Baciut, Liana Crisan, Mihaela Hedesiu, Bogdan Crisan, Florin Onisor, Gabriel Armencea, Ileana Mitre, Ioan Barbur, Winfried Kretschmer, Simion Bran
Graft copolymers of PLA which have been analyzed critically include monomers and polymers such as chitosan, cellulose, starch, polyethylene glycol (PEG), vinyl base polymers, lignin, dextran, methyl methacrylate, maleic anhydride, graphene oxide (Maharana et al. 2015). The synthesis of graft copolymers can be made by three main ways: grafting-onto (side chains are first synthesized and then attached to a linear multifunctional backbone), grafting-from (the monomer is grafted from a linear macroinitiator), grafting-through (macromonomers are copolymerized with low-molecular weight comonomers to produce copolymers) (Maharana et al. 2015).
Hydrogels for localized chemotherapy of liver cancer: a possible strategy for improved and safe liver cancer treatment
Published in Drug Delivery, 2022
Jianyong Ma, Bingzhu Wang, Haibin Shao, Songou Zhang, Xiaozhen Chen, Feize Li, Wenqing Liang
Drug delivery is one application where hydrogels special physical properties have gained attention. Controlling cross-link density in the gel matrix and affinity of hydrogels for the aqueous environment can be used to fine-tune their highly porous structure (Schiller & Lai, 2020). This allows drugs to be loaded into their gel matrix and then released in an amount that is dependent on the diffusion coefficient of small molecules or macromolecules. Due to their pharmacokinetic properties, it is possible to use hydrogels for drug delivery that is primarily focused on maintaining a high local concentration of the drug in the surrounding tissues for an extended period, while they can also be used for systemic delivery. Due to their biocompatibility, hydrogels can be used in the peritoneum and other areas of the body (Sultana et al., 2019). Hydrogels high-water content, as well as their physicochemical similarity to the natural extracellular matrix and mechanical properties, improves biocompatibility. It is possible to develop hydrogels that are biodegradable or dissolvable via environmental, hydrolytic, or enzymatic pathways, although this may not be desirable regarding the time and placement of the drug delivery device. Hydrogels, on the other hand, are somewhat pliable and may be molded to fit any surface. The muco- or bio-adhesive characteristics of some hydrogels can be helpful in the application of these hydrogels on non-horizontal surfaces or in the immobilization of these hydrogels at the application site. Rosiak et al. utilized gamma radiation to cross-link natural polymers (e.g. agar or gelatin) and synthetic polymers (e.g. poly(vinyl pyrrolidone) (PVP) or poly(vinyl alcohol) (PVA)) to produce sterile hydrogels for wound treatment. Their hydrogels are currently manufactured and marketed under the brand names 'Kikgel' and 'Aqua-gel' wound dressings (Rosiak et al., 1989). Hydrogels are being patented for contact lenses, in addition to the wound dressing. When macromonomers are used to make hydrogels, the necessity for their purification may be eliminated, because the used materials are generally nontoxic. For the synthesis, pH-sensitive polymers were used (hydroxyethyl)methacrylate-co-methacrylic acid, allowing for the production of hydrogels capable of undergoing a volume phase transition at a particular pH. This can be done by using salt solutions like sodium phosphate or sodium bicarbonate in the device in order to change the microenvironment and initiate the release of active ingredient. This solution's pH might be anywhere from 7.5–8.4 or 6.4–7.3, which could cause the hydrogel to either expand or contract (Rosenthal et al., 2006).