Temperature-responsive polymers methacrylate

In this study, we demonstrate new pH/temperature-sensitive polymers with transitions resulting from both polymer-polymer and polymer-water interactions and their applications as stimuli-responsive drug carriers [22-23], For this purpose, copolymers of (Ai,Ai-dimethylamino)ethyl methacrylate (DMAEMA) and ethylacrylamide (EAAm) [or acrylamide (AAm)] were prepared and characterized as polymeric drug delivery systems modulated for pulsatile and time release. 

By polymerizing poly(A -isopropylacrylamide) (PNIPAM) [55] or poly (2-(diethylamino)ethyl methacrylate) (PDEAEMA) [56] as a stimuli responsive polymer/hydrogel layer around a colored nanoparticle of PS-co-PMMA, the local refractive index and consequently the color intensity of the latex could be switched by the temperature [55] or pH [56]. 

All of the above features make silica colloidal crystals ideal candidates for highly selective responsive nanoporous membranes. However, until 2005, there were no publications describing transport through surface-modified colloidal membranes. In 2005, Zharov group introduced, for the first time, the concept of permselective colloidal nanoporous membranes by describing pH-responsive amine-modified colloidal membranes with controlled transport of positively charged species [26]. Later, they reported a detailed study of transport through amine-modified colloidal membranes [27], as well as membranes modified with sulfonic acids [28,29], Methods to modify the colloidal nanopores with polymers were developed [30], which allowed us to introduce temperature-responsive poly(A-isopropylacrylamide) (PNIPAAM) [31], pH- and ion-responsive poly(2-(dimethylamino)ethyl methacrylate), PDMAEMA [32], and pH- and temperature-responsive poly(L-alanine) [33], and to study the molecular transport in these polymer-modified nanoporous coUoidal membranes as a function of the environmental conditions. In this chapter we summarize these results. 

Introduction of a hydrophobic comonomer, bntyl methacrylate, in the polymer resulted in a decreased transition temperatm-e of ahont 20°C. Retention of steroids in poly(NIPAAM-co-butyl methacrylate)-grafted colnnms increases as colmnn temperature increases. The capacity factors for steroids on the copolymer-modified silica beads was much larger than that on poly(NIPAAM)-grafted columns. The effect of temperature on steroid retention on poly(NIPAAM-co-hntyl methacrylate)-grafted stationary phases was more pronoimced compared to snpports modified with poly(NIPAAM). Furthermore, retention times for steroids increased remarkably as the butyl methacrylate content increased in the copolymer. The temperature-responsive elntion of steroids was strongly affected hy the hydropho-bicity of the grafted polsrmer chains on silica surfaces (63). 

Gorga RE, Cohen RE (2004) Toughness enhancements in poly (methyl methacrylate) by addition of oriented multiwall carbon nanotube. J Polym Sci B Polym Phys 42(14) 2690-2702 Gorgieva S, Kokol V (2011) Synthesis and application of new temperature responsive hydrogels based on carboxymethyl and hydroxyethyl cellulose derivatives for the functional finishing of cotton knitwear. Carbohydr Polym 85 664-673... 

It would be of interest to add some functionalities such as properties in response to changes in pH, temperature, electrical potential and so on as well as hydrophilic properties to PTFE surfaces by the combined technique just described. Poly(AT-isopropylaoylamide) (PNIPA ) is a well-known thermo-responsive polymer whose hydrogel undergoes a volume change around 31 C in an aqueous solution. And further, poly 2-(dimethylamino)ethyl methacrylate (PDMA) in a pH 10 buffer solution exhibits a drastic decrease in the transmittance around 28 °C, which is considered to come from a phase transition of PDMA chains (ii). Therefore, we have tried to prepare JV -isopropylacrylamide (NIPAAm) or 2-(dimethylamino)ethyl... 

The most widely investigated temperature-responsive biomedical polymer is poly(A-isopropyl acrylamide) (pNIPAM). This polymer is the focus of Chapter 1 in this book, and therefore it will not be discussed in depth here. However, pNIPAM has been paired with polyampholyte copolymers and applied to nanoparticle separations (Das et al., 2008), drug delivery (Bradley, Liu, Keddie, Vincent, Burnett, 2009 Bradley, Vincent, Burnett, 2009), and tissue engineering applications (Xu et al., 2008). In a related system, latridi et al. (2011) also used the LCST-responsive properties of polyethylene glycol methacrylate (PEGMA) copolymerized with methac-rylic acid and 2-(diethylamino) ethyl methacrylate in a temperature- and pH-sensitive doxorubicin drug delivery system. However, the primary focus of this study was to demonstrate the pH-dependent release properties as discussed earlier. 

SI-IMP has been used for synthesis of different types of stimuli-responsive polymer brushes that are responsive to several external stimuli, such as pFI, temperature, and ionic strength [28,58-65]. Because materials interact with their surroundings via their interfaces, the ability to fashion soft interfacial layers and tune the range, extent, and type of physicochemical interactions across interfaces is central to a variety of applications. Rahane et al. carried out sequential SI-IMP of two monomers to create bilevel poly(methacrylic acid)-Woc/c-poly(N-isopropylacrylamide) (PMAA-b-PNIPAM) block copolymer brushes that can respond to multiple stimuli [28]. They observed that each strata in the bilevel PMAA-b-PNIPAM brush retained its customary responsive characteristics PMAA being a "weak" polyelectrolyte swells as pH is increased and the thermoresponsive PNIPAM block collapses as temperature is raised through the volume phase transition temperature due to its lower critical solution temperature (LCST) behavior. As a result of ions added to make buffer solutions of various pH and because of the effect of surface confinement, the swollen-collapse transition of the PNIPAM layer occurs at a... 

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