On the supramacromolecular structure of core–shell amphiphilic macromolecules derived from hyperbranched polyethyleneimine
Graphical abstract
Introduction
The search for smart building blocks has attracted the attention of the soft-matter community for a while [1], [2], [3]. Among others, amphiphilic building blocks have the ability to adopt several structural conformations by tuning their thermodynamic variables [4].
Along these lines, dendrimers and dendrimeric structures with amphiphilic core–shell architectures displaying micelle-like properties, proved to be attractive building blocks to form supramolecular materials with designed properties [5], [6]. Seminal works of Percec [7], [8], [9] and Meijer [10], and their co-workers, provided the framework for designing an unprecedented number of superstructural assemblies from precisely engineered dendrons and dendrimers.
In particular, the modification of peripheral groups of hydrophilic dendrimers with hydrophobic tails led to the creation of molecularly defined systems with inverse micelle properties [10], [11]. However, dendrimer synthesis is time consuming and limits their application almost to laboratory scale. Alternatively, core–shell amphiphilic macromolecules (CAMs) [12], [13] with hyperbranched cores [14], a less perfect variant of the dendrimers have gained popularity, among other properties because of the possibility of easy synthesis of unimolecular micelles [15], [16], [17].
CAMs with unimolecular micelar (unimicelar) structures can behave in different ways allowing a tuning of their aggregation state depending on solvent, temperature conditions [18] external fields, pressure, etc. Unimicelles derived from hyperbranched polyethyleneimine (HPEI) are very well known, and they probe their versatility as phase transfer agents among other properties [19], [20], [21], [22], [23]. Despite the number of papers reporting results in solution/suspension using HPEI as polar core, to date, there is a lack of information on the structure of HPEI CAMs in solid state.
However, molecular and supramolecular properties are far from being the ultimate hierarchical level and interesting properties arise from supramacromolecular assembly [24]. Recently, we used supramacromolecular assemblies of HPEI-C16 to organize gold nanoparticles into lamellar structures [21]. Among other techniques, Langmuir–Blodgett film assembly has proven to be one of the most versatile methods for controlled assembly of interfacial dendritic structures [25], [26], [27], [28], [29], [30], [31], [32].
In this paper we investigate the supramacromolecular structure and properties of the amphiphilic structure (HPEI-Cn) formed by the hyperbranched polar polymer polyethyleneimine (HPEI) and long chain saturated fatty acids (Cn, n = 8, 10, 12, 14, 16 and 18. From now on, Cn will indicate the whole set of chain lengths) in toluene suspension, solid state and Langmuir films at air–water interface.
Section snippets
Materials and methods
Hyperbranched polyethyleneimine (HPEI, Mn = 10,000 Da) and fatty acid chlorides (capryl, capric, lauryl, myristoyl, palmitoyl and stearoyl chlorides) were purchased from Sigma–Aldrich. Triethylamine (TEA) was purchased from Sintorgan. All chemicals and solvents used were of the maximum purity available in market. Prior to use, HPEI was kept in vacuum for 2 days, chloroform and TEA were purified and dried following standard protocols [33].
The synthesis of HPEI capped with carboxylic acids via amide
HPEI-Cn CAMs suspended in toluene
The amphiphilic nature of HPEI-Cn with a hydrophilic core partially shielded by an aliphatic shell (the degree of capping in our CAMs was kept fixed at 52%) opens the possibility to tune the supramacromolecular structure of the micelles controlling solvent properties (temperature, electric susceptibility, etc.). In fact, Picco et al. [18] showed that HPEI-C16 displays a liquid crystal-to-colloid thermally activated transition near room temperature. Moreover, HPEI-C16 displays also negative
Conclusions
Supramacromolecular assembly of functional soft-matter structures proves to be a flexible strategy for controlling material properties [1], [2], [3] and designing novel collective behavior.
CAMs with hyperbranched polyethyleneimine core building blocks are especially useful acting as unimicelles, based on the ability to transfer polar substances to non-polar media due to the hydrophilic nature of the cores. Previous results on HPEI-C16 unimicelles demonstrated that tight control over
Author contributions
The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript.
Acknowledgments
A.S.P. is recipient of a CONICET doctoral fellowship. O.A., G.S. and M.C. are staff members of CONICET (Argentina). O.A. gratefully acknowledges financial support from the Max Planck Society (Germany), ANPCyT (Argentina, Projects: PICT/PRH 163/08 and PICT-2010-2554). O.A. and M.C. acknowledges Laboratório Nacional de Luz Síncrotron (Campinas – Brazil, proposals SAXS1-10737, SAXS1-13502 and SAXS1-14537) for partial financial support. The authors acknowledge the contribution of Lic. Agustín
References (59)
Progress Polym. Sci.
(2005)- et al.
React. Funct. Polym.
(2010) - et al.
J. Colloid Interface Sci.
(2009) - et al.
J. Colloid Interface Sci.
(2013) - et al.
J. Colloid Interface Sci.
(2009) - et al.
J. Colloid Interface Sci.
(2002) - et al.
Colloids Surf. A: Physicochem. Eng. Aspects
(2005) - et al.
Polymer (United Kingdom)
(2013) - et al.
Polymer
(2008) - et al.
Polymer
(2013)
Chem. Phys. Lipids
J. Lipid Res.
Fluid Phase Equilib.
Science
Science
Chem. Commun.
Soft Matter
Chem. Rev.
Chem. Rev.
Nature
Science
J. Am. Chem. Soc.
J. Am. Chem. Soc.
Macromolecules
Hyperbranched Polymers: Synthesis, Properties, and Applications
Soft Matter
Soft Matter
Chem. Rev.
Chem. Commun.
Cited by (8)
Molecularly imprinted self-buffering double network hydrogel containing bi-amidoxime functional groups for the rapid hydrolysis of organophosphates
2023, Journal of Hazardous MaterialsCitation Excerpt :For the preparation of the second network with pH buffer function, PEI is a type of heterogenized polymeric base with amine-rich chemical composition and the well-known proton sponge effect, which implies a high potential buffering ability for accelerating the hydrolysis reaction of organophosphorus compounds (Choi and Kim, 2019). Besides, PEI is a commercialized and readily available cationic polymer (Picco et al., 2014; Yang et al., 2021), thus, we used the crosslinked PEI as the second network of the hydrogel material in order to realize the rapid hydrolysis of OPs in practical conditions. Herein, we designed a multifunctional molecularly imprinted double network hydrogel by integrating the catalytic active polymer and the cationic polymer polyethyleneimine (PEI) to prepare a practical catalyst material, realizing the construction of stable molecularly imprinted structure with high catalytic activity and PEI-induced pH buffering ability.
Formation and characterization of Langmuir and Langmuir-Blodgett films of Newkome-type dendrons in presence and absence of a therapeutic compound, for the development of surface mediated drug delivery systems
2017, Journal of Colloid and Interface ScienceCitation Excerpt :Instead, a continuous increase in pressure, as the available surface area per molecule decreases, is observed in both BBA and BTA dendrons π-A compression isotherms, and no changes are noticeable in the compression modulus. These results allow us to infer that the dendrimeric structures are gradually accommodated in the air-water interface during compression, showing a second order transition from the gaseous to the condensed phase [51,52]. However, for the three studied dendrons the maximum compression modulus values are similar and around 40 mN/m, which are lower than those generally obtained for amphiphilic molecules with linear non-polar chains [52].
Hexagonal phase with ordered acyl chains formed by a short chain asymmetric ceramide
2017, Colloids and Surfaces B: BiointerfacesSynthesis of Modified Hyperbranched Polyethyleneimine and Its Application in Demulsification
2021, Shiyou Xuebao, Shiyou Jiagong/Acta Petrolei Sinica (Petroleum Processing Section)