Synthesis and Characterization of Star-Shaped (PCL-B-PEG) as Potential Electrospun Microfibers

Abstract

Star-shaped polymers have vast potential in application due to their architecture. In this study, a 6-arm star-shaped of poly(ԑ-caprolactone)-b-poly(ethylene glycol), (6PCG) was synthesized via ring opening polymerization, (ROP) of ԑ-caprolactone and Steiglich esterification (coupling reaction) to attach the PEG arm to the star-shaped polymer with discrete core of dipentaerythritol. The polymer chemical structure was characterized by FT-IR. The molecular weight (Mn) determined from 1H NMR spectra showed that the star polymer has approximately the same molecular weight as the theoretical value. The polydispersity index indices (PDI) (>1.5) from GPC were narrow suggesting controlled polymerization reaction. Thermal stability of the star-shaped 6PCG were examined using thermogravimetric analysis, (TGA) and differential scanning calorimetry, (DSC) and showed slight increase compared to homopolymer star PCL due to the changes of end-group functionalities. Six-arm star-shaped PCL-b-PEG was dissolved in chloroform/methanol solvents and the resulting solution was used for electrospinning process. The morphology of nanofibres showed fine fibres without beads and thus a possible potential for several applications. FT-IR. Berat molekul (M n ) yang ditentukan daripada spektrum 1H NMR menunjukkan bahawa polimer bintang ini mempunyai berat molekul yang hampir sama sebagai nilai teori. Indeks kepolitaburan (PDI) (>1.5) yang diperoleh daripada analisis GPC mencadangkan tindak balas pempolimeran adalah tindak balas terkawal. Kestabilan terma 6PCG polimer berbentuk bintang ini telah dianalisis menggunakan analisis termogravimetrik, (TGA) dan kalorimetri imbasan perbezaan (DSC) dengan ia menunjukkan peningkatan kestabilan terma berbanding homopolimer bintang PCL disebabkan oleh perubahan kumpulan berfungsi terminal akhir. Polimer PCL-b-PEG berbentuk bintang dengan 6 cabang ini kemudiannya dilarutkan dalam pelarut kloroform/metanol dan larutan yang terhasil digunakan untuk proses elektroputaran. Morfologi nanogentian yang terhasil menunjukkan gentian halus tanpa manik menjadikan gentian ini berpotensi untuk aplikasi yang luas. ABSTRAK Polimer berbentuk bintang memiliki potensi yang besar dalam pelbagai aplikasi kerana reka bentuknya. Dalam kajian ini, polimer berbentuk bintang dengan 6 cabang poli(ԑ-kaprolakton)-b-poli(etilena glikol), (6PCG) disintesis melalui pempolimeran pembukaan gelang, (ROP) ԑ-kaprolakton dan pengesteran Steiglich (tindak balas gabungan) untuk menggabungkan PEG kepada polimer berbentuk bintang dengan teras diskret dipenteritritol. Struktur kimia polimer dicirikan oleh

The implications of population ageing on economic growth: Evidence of nonlinearity

“…This study investigated the impact of population ageing on economic growth by proxying the growth rate of GDP per capita for economic growth in line with previous empirical growth models (Antonakakis & Workie, 2023;Lee & Shin, 2019;Papapetrou & Tsalaporta, 2020). In contrast to majority of the prior studies, which assumed a linear relationship between population ageing and economic growth (Bawazir et al, 2020;Eggertsson et al, 2019;Fukuda & Morozumi, 2004;Herzog, 2012;Huang et al, 2019;Ismail et al, 2016;Li & Zhang, 2015;Lindh & Malmberg, 2009;Maestas et al, 2023;Mamun et al, 2020;Miri et al, 2019;Park et al, 2012;Ruidong, 2018;Uddin et al, 2016;Wongboonsin & Phiromswad, 2017;Zhao et al, 2018), our study analyses a non-linear relation. Our findings of a non-monotonic relation, trace similarities to those of a few researchers who have also found evidence of the same (Antonakakis & Workie, 2023;Lee & Shin, 2019;Liu, 2013;Yang et al, 2021;Zhang et al, 2003).…”

“…A few of these examine the impact exclusively on a specific country. In this vein, Ismail, Abd Rahman, Tengku Abdul Hamid, and Said (2016) identify adverse growth repercussions due to an ageing populace from 1980 to 2011 in Malaysia by applying the Autoregressive Distributed Lag (ARDL) technique. Uddin, Alam, and Gow (2016) confirmed a significant negative impact on per capita GDP in Australia due to a rising dependency ratio, using the Dynamic Ordinary Least Squares (DOLS) from 1971 to 2014.…”

Asian ageing: The relationship between the elderly population and economic growth in the Asian context

“…Baharin and Saad [ 40 ], using the autoregressive distributed lag (ARDL) approach and a vector error correction model, corroborated these results showing that the ageing population has had a major impact on healthcare costs in Malaysia. Ismail, Abd Rahman [ 41 ] provided the reduced old-age dependency may result in lower tax and social security contributions paid by employed people to fund retirement income and health care for the elderly, which may increase labor supply. This results in fewer mouths to feed and more disposable income that can be invested in the economy’s growth.…”

“…These efforts will help mitigate the harmful effects of ageing and generate economic benefits. Ismail, Abd Rahman [ 41 ] and Taasim [ 47 ] used ARDL in their research and discovered that the elderly population, the elderly dependence ratio, and lower fertility contribute to economic development. Population ageing benefits economic growth, according to Futagami and Nakajima [ 48 ], who cited innovations in labour-saving technologies and more expenditures in human capital as examples.…”

Hydrophobic Drug Carrier from Polycaprolactone-b-Poly(Ethylene Glycol) Star-Shaped Polymers Hydrogel Blend as Potential for Wound Healing Application

“…Of particular interest to biomedical applications are biodegradable and biocompatible starshaped block copolymers with hydrophobic inner parts and hydrophilic outer parts. Drug entrapment can be enhanced by using star-shaped polymers because it gives additional drug-conjugated sites for drug loading [15]. In recent years, the star-shaped drug delivery system has been thoroughly studied for its drug loading capacity in particular and has demonstrated many features in terms of drug entrapment, the pattern of drug release, critical micelle concentrations, and cytotoxicity [16,17].…”