Materials Science-Poland http://www.materialsscience.pwr.wroc.pl/ DOI: 10.2478/msp-2021-0015 Characterization study of polyAMPS@BMA core-shell particles using two types of RAFT agents Nasrullah Shah1,∗, Zubair Ullah Khan1, Manzoor Hussain1, Touseef Rehan2, Abbas Khan1 1Department of Chemistry, Abdul Wali Khan University Mardan, Mardan, KP 23200, Pakistan 2Department of Biochemistry, Shaheed Benazir Bhutto Women University, Peshawar, KP 25000, Pakistan The study and application of reversible addition-fragmentation chain transfer (RAFT) polymerization have been widely reported in the literature because of its high compatibility with numerous monomers, reaction conditions, and low polydispersity index. The effect of RAFT agents on the characteristics of the final product is greatly needed to be explored. Our present study aimed to compare the influence of two different types of RAFT agents on the characteristics of the water-soluble polymer(2- acrylamido-2-methylpropane sulfonic acid) (polyAMPS) and their polyAMPS@butyl methacrylate (BMA) core-shell particles. Different analytical techniques including scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), and thermogravimetric analysis (TGA) were used to ascertain the final morphological, structural, and thermal properties of the resultant products. It was found that RAFT agents haveshown a clear influence on the final properties of the resultant polyAMPS and their core-shell particles such as particle size,shape, size distribution, and thermal behavior. This study confirms that RAFT agents can control the final properties of thepolymers and their core-shell particles. Keywords: RAFT agents, effect of RAFT agents, polyAMPS, core-shell particles, characterization 1. Introduction plex architectures, narrow molecular weight dis- tributions, and pre-determined molecular weights Polymers became the center of research over [9]. This thiocarbonylthio functionality is provided the past few decades due to their good adapt- by reversible addition-fragmentation chain-transfer ability [1,2] and various potential applications in (RAFT) agents, which leads to RAFT polymeriza- the field of medical [3,4], pharmaceutical [5], tion. Since the invention of RAFT polymerization, and other industrial applications [6,7]. The pre- numerous RAFT agents have been synthesized and requisite for complete control over the applica- reported [10]. tion of polymers is the "polymerization process". RAFT polymerizations have been used in the The advantages and shortcomings of polymeriza- synthesis of various polymeric architectures, such tion process are dependent on its low versatil- as star [11], brush [11], linear [12], dendrimer [13], ity or compatibility over different monomer, sol- core-shell [14], and graft [15], along with differ- vent system, provided conditions and suitable ini- ent conditions, namely, solution, suspension, emul- tiators [8]. One of the most prominent polymer- sion, and miniemulsion polymerizations [16]. Dis- izations include controlled/living radical polymer- persity is one of the prominent parameters that af- ization (CLRP). Among all other CLRP, the most fects the properties of polymers. Control over dis- advance type of polymerization which uses thio- persity can be attained by mixing two RAFT agents carbonylthio functionality, provides relatively high with adequately dissimilar chain-transfer behav- versatility over a provided condition (solvent, tem- iors in different ratios, affording polymers with perature, pH and initiator), functional and nonfunc- monomodal molecular weight distributions over a tional monomers to yield desire material with com- broad dispersity range [17]. Henkel and Vana [18] studied the effect of RAFT agents on the mechan- ∗E-mail: [email protected] ical and the microstructure behavior of poly(butyl © 2021. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License. (http://creativecommons.org/licenses/by-nc-nd/4.0/) Nasrullah Shah et al. acrylate). For this purpose, a photoinitiated poly- soluble polymer (2-acrylamido-2-methylpropane merization of 1,4-butanediol diacrylate and butyl sulfonic acid) (polyAMPS) and their core-shell acrylate was conducted in the absence and pres- particles has not been reported. Hence, considering ence of RAFT agents. It was found that RAFT- various advantages of RAFT polymerization, this based polymers have lower Young’s moduli and effort was made to determine their role in control- high swelling degree. Moreover, kinetic differen- ling the thermal stability, particle size distribution, tial scanning calorimetry studies illustrated that the crystallinity, and average particle size of the resul- gel point was retarded with enlarging the content of tant core-shell particles with polyAMPS as a shell RAFT agent [18]. Masuda and Takai [19] studied and butyl methacrylate (BMA) as a core. the effect of RAFT agent content on the microstruc- ture and properties of poly(N-isopropylacrylamide) 2. Experimental section (PNIPAAm) gels. A millimeter-sized cylinder was synthesized from PNIPAAm gels. Swelling and 2.1. Materials deswelling behaviors were studied, and we found Potassium persulfate, sodium hydride, mag- that a cylinder with high "RAFT agent content" nesium turnings, and carbon disulfide were showed fast deswelling properties [19]. The var- purchased from Daejung, Korea. 4-vinylbenzyl ious multi-arm RAFT agents have been used in chloride, 4,4’-azobis(4-cyanovaleric acid) stereolithographic 3D printing. Further, it was (ABCA), dimethylformamide (DMF), BMA, widely found that changing the functionality and 2-acrylamido-2-methylpropane sulfonic acid content of RAFT agents result in obtaining con- (AMPS), iodine, magnesium sulfate, potassium trol over material mechanical behavior in a broad persulfate (K S O ), n-hexane, diethyl ether, span [20]. Application of RAFT polymerization in- 2 2 8 bromobenzene, dimethyl sulfoxide, petroleum stead of free radical polymerization produced ma- ether, and tetra hydrofuran were purchased from jor variations in the mechanical, uptake behaviors Sigma-Aldrich. Pyrroles and silica gel were the and thermal properties, which seem to reflect the products of Unichem, USA. improvement in polymer uniformity and mobility frequently related with controlled polymerization 2.2. Instruments used [21]. The application and properties of core-shell The FTIR analysis was done via Thermo Fisher nanomaterials can be promisingly controlled by the Scientific model NICOLET iS5. Scanning electron right selection of shell or core materials according microscopic and energy dispersive X-ray analyses to the environment/condition and applications. A were done via field-emission scanning electron mi- vast study of core-shell material "as sensing" de- croscopy (SEM), JEOL Japan, model JSM5910, vice have been reported, i.e., as optical sensors, gas with an acceleration voltage of 30 KV. X-ray adsorptive sensors, electrochemical sensors, and diffraction (XRD) pattern was recorded via an wearable sensing devices. These devices have var- X-ray diffractometer (model JDX-3532), JEOL ious potential uses in food analysis and biologi- Japan, by using Ni-filtered Cua K radiation and cal, industrial, environmental, and clinical appli- a wavelength of 1.5418 Å. Thermogravimetric cations. Moreover, numerous synthetic approaches analysis was done with TGA instrument from with various prominent properties of core-shell ma- PerkinElmer (USA), model TGA 4000. terials, such as high ion transport properties, high 2.3. Preparation of RAFT agents conductivities, and high surface area have been studied. [22] In the study, two different RAFT agents Although the synthesis of RAFT agents and 4-vinylbenzyl pyrrolecarbodithioate and 4- their use in the preparation has already been re- vinylbenzyl dithiobenzoate (4VP and 4VD, ported [23, 24], to our knowledge, their effect respectively) were separately prepared using the on the final characteristics of the prepared water- reported protocols with some modifications [24]. Characterization study of polyAMPS@BMA core-shell particles using two types of RAFT agents Briefly, for the preparation of 4VP, 6.02 gofNaH ide under an oxygen-free environment. The react- was mixed in 160.00 ml of DMF, followed by ing flask was deoxygenated with nitrogen gas purg- stepwise addition of 10.02 g/20 ml of pyrrole, 9.01 ing and vacuum pump followed by fitting it to wa- ml/20 ml CS2, and 22.2/20 ml of 4-vinylbenzyl ter bath for 12 h at 333 K. After 12 h at 333 K, chloride, which were all dissolved in DMF. The a brownish color polyAMPSi was prepared which mixture was stirred for 12 h. For the isolation was stored at 268 K in an inert environment. The of 4VP, the resultant product was washed with same protocol was used for polyAMPSii but 4VP diethyl ether and distilled water (1:1), followed by was replaced with 4VD. extraction via column chromatography, in which petroleum ether was used as a mobile phase. The 2.5. Preparation of core-shell particles petroleum ether was separated through vacuum For the preparation of CSi, 25 ml of BMA was distillation, and the final product, 4VP, was stored slowly added to 1 g/300 ml of polyAMPSi solution at -18 ◦C in an inert environment. For the syn- in distilled water, followed by addition of potas- thesis of 4VD, 3.301 g of magnesium turning sium persulfate (K S O ) solution (1 g/15 ml). The was dissolved in 14 ml/40 ml bromobenzene