فصلنامه بسپارش
سال نهم شماره 2 (پیاپی 31، تابستان 1398)

Mucoadhesive polymers were first used in the early 1980s to design mucoadhesivebuccal drug delivery systems. These systems have been introduced as novel drugdelivery systems due to the ability to stick and stay on mucus membranes and slow release ofthe drug and as suitable alternative to overcome the problems of common oral drug deliverysystems. Mucoadhesive systems can be prepared in various forms, such as tablet, gel, oralfilm, spray, viscous solution and micro/nanoparticles, and can be used for drug deliveryfrom the buccal, sublingual, intestine, ocular, nasal, vaginal, and other mucosal routes.Mucoadhesive polymers which are the most important component of the drug deliverysystems, are usually natural, synthetic or semi-natural hydrophilic macro-molecules,containing functional groups forming hydrogen bonds, such as carboxyl and hydroxylgroups, or amines. Hence, mucoadhesion depends on the reaction between the polymer andthe mucus and the adhesion strength is determined by the different polymer characteristicsand the medium conditions in which the polymer resides. In this article, the discussioncovers mucoadhesion mechanism and its effective factors; natural mucoadhesive polymers,synthetic and semi-natural mucoadhesive polymers; the properties and characteristics ofthese polymers; their application in the design and development of mucoadhesive systemsand also the new generation of mucoadhesive polymers such as thiolated mucoadhesivepolymers.

Polyvinylidene fluoride (PVDF) is a semicrystalline polymer which has been extensivelyapplied in scientific research and industrial processes owing to its desirable featuressuch as excellent dielectric properties, suitable mechanical resistance, high thermal stability,good chemical resistance. PVDF membranes can be applied in a wide range of applicationsincluding waste water treatment, gas separation, and separator and polymer electrolyte inlithium ion batteries. PVDF-based polymer electrolytes in lithium ion batteries should havelow thickness as well as an appropriate porosity with good mechanical strength and highelectrochemical stability. Applying pristine PVDF based polymer electrolytes may causeinternal short circuit which will influence the performance of the Li-ion batteries. BlendingPVDF with other polymers and incorporation of inorganic fillers have been considered aseffective methods to improve the performance of PVDF-based electrolytes. In this paper,PVDF-based electrolytes and their performance requirements have been investigated. Thefabrication methods of PVDF membranes and the known strategies which are applied toimprove their mechanical and electrochemical characteristics have also been described.Furthermore, the ionic conductivity and electrochemical performance of PVDF-basedlithium-ion batteries are discussed.

Generally, polymer surface engineering has vast applications in biotechnology,membranes, self-cleaning and electronic devices. These applications are based oncontrollable changing in some properties such as surface energy, surface topography, andbiocompatibility of polymer. For choosing a proper method for the surface modificationof polymer, three parameters should be considered carefully. These parameters include:chemical structure of polymer which is focused on strengths and weaknesses of demandedpolymer, the surface properties that we need to achieve after treatment and finally surfacegeometry which is related to the presence or absence of porosity and or chemical andphysical heterogeneity of polymer surface. This research investigates the popular surfacemodification methods like wet chemistry, flame, plasma, UV radiation, laser and grafting.Furthermore, for accurate understanding of quantitative and qualitative changes of surfaceproperties of polymers, the general characteristics of used methods (depth analyzed,resolution, and analytical sensitivity) were briefly mentioned. Some of the popularmethods for include contact angle measurement, Fourier-transform infrared spectroscopy(FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-rayphotoelectron spectroscopy (XPS), secondary-ion mass spectrometry (SIMS), Augerelectron spectroscopy (AES) and scanning tunnelling microscopy (STM).

Technological advances in the field of novel polymeric drug delivery systems havebeen formulated with long-term releases. Such formulations are a great method forchronic diseases, especially when the lack of compliance may be effective in responding totreatment. New drug delivery systems have provided an opportunity to overcome many ofthe challenges associated with the treatment of AIDS through anti-retroviral drugs (ARVs)and thus improving patients with AIDS. In this paper, a comprehensive review of thedifferent polymeric systems for release of ARVs to achieve its sustained release kineticshas been addressed. Potentialities of different systems and routes for administration of ARVdrugs, such as transdermal, buccal and rectal delivery have been studied. Physico-chemicalproperties, in vitro and in vivo performance such as sustained release from tablets, ceramicimplants, polymer nanoparticles, nano reservoirs, liposomes, polymer mixture, emulsions,microemulsions, nanopowders and etc are summarized. Increasing awareness aboutpolymeric systems that cause the long-term release of ARVs will facilitate the developmentof this strategy to achieve potential benefits. This review shows the significant potential ofnovel polymeric drug delivery systems and polymer inhibitors used to treat AIDS patientseffectively with future ARVs.

Acrylic-styrene latexes are being used in various industries such as textiles, rubber,plastics, adhesives and coatings due to unique properties such as good durability,compatibility with other materials, adhesion and ability to form continuous film, highresistance to ultra violet, oxygen, water and solvents. In this paper, the most effectivefactors on optimization of acrylic-styrene latexes' synthesis are studied namely: the typeand concentration of monomer, initiator and emulsifier, and temperature of polymerizationreaction. Optimized stable latex with the desirable performance may be achieved throughthe following conditions: using butyl acrylate monomer as an optimum acrylate monomerin combination with styrene hard monomer in the weight ratio 1-1.35, respectively; addingfunctional monomers like α-methacrylic and acrylic acid of about 2 wt% relative to thetotal weight of monomers, improving the film forming process via imparting cross-linkingcites into the acrylic chains; utilizing anionic emulsifier alone (like DSB and SDS) or incombination with nonionic ones (like OP-10 and TX100) of about 0.5 wt% to 3 wt% ofthe monomers; and using radical initiators like persulfates of potassium and ammoniumof about 0.25-0.5 wt% relative to the total monomers' weights. The reaction optimumtemperature range is determined to be approximately 75-80 °C. Adding fillers such asrosin and silica nanoparticles into the acrylic-styrene matrix as much as 4 and 5 wt%,respectively, results in improved water resistance of their films.

Technologies based on microwave absorption are based on science of absorber materialsin this frequency range. The nature of microwave is an alternating electrical andmagnetic field that could be naturally absorbed in transmission through materials with nonzeroconductivity or imaginary part of permittivity (dielectric loss) and nonzero imaginarypart of magnetic permeability (magnetic loss). Meanwhile, microwave absorbing polymercomposites due to their light weight, low fabrication cost, and high performance havesignificant importance. Polymer matrix of these composites are generally nonconductivematerials that are host for microwave absorbing materials such as carbon nanotube, ferrite,and titanium dioxide, and so conductivity enhancement of polymer matrix could be effectiveon improvement of absorption mechanism especially in nonconductive magnetic absorbers.In this regard, polyaniline as a conductive polymer, has important role in improvementof quality of absorbing composites in microwave range. Also, improvement of variouscharacteristics of polyaniline has strong dependence on properties of other componentsand especially on synthesis method. Therefore, especial consideration on various kinds,components, and synthesis methods of such composites and key role of polyaniline intheir properties is critical for researchers in the field. In this paper, after introducing themechanism of electromagnetic wave absorption, we introduce different kinds of compositesincluding polyaniline with other organic and inorganic materials, synthesis methods, andproperties related to design of microwave absorbers.