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Polymers as Coagulants for Wastewater Treatment
Published in Sreedevi Upadhyayula, Amita Chaudhary, Advanced Materials and Technologies for Wastewater Treatment, 2021
Sai Harsha Bhamidipati, Dharani Prasad Vadlamudi, Sudheshna Moka
A copolymer is a polymer that is made up of two or more monomer species. Redox polymerization is a common method used for copolymerization. Redox polymerization is normally used for hybrid materials based on poly-acrylamide (Lee et al., 2012b; Qian et al., 2004; Yang et al., 2004). Many materials, such as Al(OH)3-PAM, and PGS-PAM, are synthesized using this method in which acrylamide is polymerized in the colloidal solution of palygorskite (PGS) and Al(OH)3 in the presence of various redox initiators.
Role of Different Bioreactor Types and Feeding Regimes in Polyhydroxyalkanoate Production
Published in Martin Koller, The Handbook of Polyhydroxyalkanoates, 2020
Geeta Gahlawat, Sujata Sinha, Guneet Kaur
A strategy was developed to convert crude glycerol and activated sludge for production of PHA through aerobic dynamic feeding [45]. A PHA accumulating mixed microbial culture in a sequencing batch reactor (SBR) was able to accumulate both P(3HB) and 3HV monomers in the molar ratio of 60:40. A maximum PHA content of 80% was achieved as a biomass dry weight with a production yield of 0.7 mg C PHA/mg C. This method was the classical case of converting waste to value-added products. Copolymers showed better mechanical strength than their homopolymer counterparts. The maximum PHA productivity achieved was 193–236 mg/(L·h) and biomass concentration increased from 0.7 to 2 g/L when the organic loading rate (OLR) was increased from 360–1000 mgC/(L.d). Direct utilization of crude glycerol without pre-treatment reduced the cost significantly.
Directed Self-Assembly of Block Copolymers
Published in Bruce W. Smith, Kazuaki Suzuki, Microlithography, 2020
Chi-chun Liu, Kenji Yoshimoto, Juan de Pablo, Paul Nealey
For those who are not familiar with polymer chemistry, here is a short review of the terms that will be used throughout the chapter. Polymers are composed of one or more repeating units, i.e. monomers. A homopolymer is a polymer made of only one type of monomer, for example, a polystyrene homopolymer is made of styrene monomers, as shown in Figure 13.2. A copolymer refers to a polymer composed of more than one monomer. Given a simple linear copolymer made of A and B monomers, based on the sequence of monomers in the chain, which is determined by the polymer synthesis method [14], one could imagine that there exist several different types of copolymers. Two commonly seen examples are the random copolymer and the block copolymer: the former has no specific order for the monomer position in the chain while the latter has all the same type of monomers grouped together. Furthermore, diblock is the simplest form of block copolymer structure while triblock, such as ABA or ABC, multi-block, or non-linear block copolymers can be synthesized as well. In this chapter, we will only discuss random and diblock copolymers, thus the term “block copolymer” (or BCP) will simply refer to the diblock copolymer.Commonly used polymer terminology.
Transferrin/folate dual-targeting Pluronic F127/poly(lactic acid) polymersomes for effective anticancer drug delivery
Published in Journal of Biomaterials Science, Polymer Edition, 2022
Qing Xiao Wang, Xiang Chen, Zi Ling Li, Yan Chun Gong, Xiang Yuan Xiong
Cancer is still one of the major diseases afflicting mankind nowadays. Over the past decades, the development of drug carriers, such as liposomes, micelles, nanoemulsions and polymeric nanoparticles has attracted a great deal of attention in targeting drug delivery systems [1–3]. A number of such delivery systems have been approved for cancer therapy in the clinics, with many more currently under clinical trials or preclinical evaluations [4, 5]. Among these systems, the use of amphiphilic block copolymers as drug carriers went into the focus of current research. Because various forms of morphologies such as the spheres, polymersomes, rods, lamellas and so on can be formed by changing the composition of hydrophobic and hydrophilic blocks on the polymer chains [6, 7]. Polymersomes (also called polymer vesicles, Ps) composed of a hydrophilic core and hydrophobic bilayer are good candidates for drug delivery applications because both hydrophilic and hydrophobic drugs can be loaded in the Ps [7–11]. The application of Ps as nano-carriers in drug delivery systems has been widely studied [12–17]. Our team has also reported that Ps self-assembled from Pluronic and poly(lactic acid) (PLA) were able to enhance the absorption of anticancer drugs [18]. PLA has been extensively reported due to its excellent biodegradability and biocompatibility. Pluronic block copolymers composed of hydrophilic poly(ethylene oxide) (PEO) and hydrophobic poly (propylene oxide) (PPO) show good cell permeability [19]. Both PLA and Pluronic block copolymers have been approved as pharmaceutical ingredients by the US Food and Drug Administration.
Integrated CNTs/SiO2 nano-additives on SBS polymeric superhydrophobic coatings for self-cleaning
Published in Surface Engineering, 2020
Bin Chen, Zaosheng Lv, Fen Guo, Yanfen Huang
It is generally considered that the wettability of a solid surface is dependent on its chemical composition and surface roughness. Furthermore, two necessary conditions to fabricate superhydrophobic coatings are multi-scale nano/microstructures and low surface energy. SBS as triblock copolymers containing hydrophobic polystyrene segments. Copolymers usually have better strength, toughness and other properties than single polymers. In this study, SBS was used as a film-forming material to provide low surface energy. CNTs were used to construct the multi-scale roughness of the composite coatings. The integration of CNTs and SBS satisfied the two necessary conditions to fabricating superhydrophobic coatings. Compared with the addition of only CNTs, the addition of a small amount of hydrophobic SiO2 nanoparticles can further improve the surface roughness of the coatings, ultimately leading to an improvement in self-cleaning properties.
Fabrication of honeycomb films by the breath figure technique and their applications
Published in Science and Technology of Advanced Materials, 2018
Various kinds of polymers have been used to prepare honeycomb films (Figure 3). The amphiphilicity and functionality of the polymers should be chosen based on the intended function. Amphiphilic polymers stabilize the template water droplets, and should satisfy the various conditions shown in Section 3.2. Amphiphilic polymers, which have both hydrophobic and hydrophilic moieties, are suitable for fabricating honeycomb films because interfacial tension is an important factor in controlling the uniformity and shapes of pores. Furthermore, functional polymers suitable for the applications of the honeycomb films should be chosen. Polymer architectures are also important for controlling the structures and properties of honeycomb films. Homopolymers, random copolymers, block copolymers, and other polymers with unique architectures have been reported.