Synthesis of Organic/Inorganic Polyhedral Oligomeric Silsesquioxane-Containing Block Copolymers via Reversible Addition–Fragmentation Chain Transfer Polymerization and Their Self-Assembly in Aqueous Solution

Abstract

Polyhedral oligomeric silsesquioxane (POSS)-containing homopolymers (PHEMAPOSS) with a high degree of polymerization (DP) were synthesized via reversible addition–fragmentation chain transfer (RAFT) polymerization. PHEMAPOSS was used as a macro-RAFT agent to construct a series of amphiphilic diblock copolymers, PHEMPOSS-b-PMAA (poly (methyl methacrylate)), which possessed a different length of hydrophilic chains. The self-assembly behavior of PHEMPOSS-b-PMAA in aqueous solution was studied by transmission electron microscopy (TEM), atomic force microscopy (AFM), and dynamic light scattering (DLS), respectively. The results showed that PHEMAPOSS45-b-PMAA523 forms typical core–shell spherical micelles where the hydrophobic PHEMAPOSS blocks as the core and hydrophilic PMAA blocks as the shell. With increasing PMAA chain length, PHEMAPOSS45-b-PMAA1173 with a longer PMAA chain self-assembled into irregular aggregates with POSS moieties dispersed in the aggregates. On the other hand, PHEMAPOSS45-b-PMAA308 with a shorter hydrophilic PMAA chain could self-assemble into a dendritic cylinder structure.

Effect of polyhedral oligomeric silsesquioxane nanocage on the crystallization behavior of PEG 5k ‐ b ‐P(MA‐POSS) diblock copolymers achieved via atom transfer radical polymerization

“…The first example of POSS‐based well‐defined block copolymers by ATRP was reported by Matyjaszewski's group, having poly( n ‐butyl acrylate) (P(nBA) middle block and poly(methacrylate‐POSS) (P(MA‐POSS) . Because then, a number of well‐defined block copolymers of POSS with polylactide (PLA), poly(methyl methacrylate‐ co ‐glycidyl methacrylate), P(MMA‐ co ‐GMA)‐ b ‐P(MA‐POSS) and P(MA‐POSS)‐ b ‐P(MMA‐ co ‐GMA)‐ b ‐P(MA‐POSS), poly(ethylene glycol)methyl ether methacrylate (PEGMA), poly( N ‐isopropylacrylamide) (PNIPAAm), and others have been reported. We and others have recently published extensive reviews on POSS‐based hybrid (co)polymers and their applications …”

Self-Assembly and Applications of Amphiphilic Hybrid POSS Copolymers

“…The size of POSSs depends on the surrounding R groups, where R could be a hydrogen atom or organic functional groups which could be precisely functionalized via the living/controlled polymerization techniques [ 24 ]. POSSs have been reported to construct hybrid polymers with well-defined structures, including telechelic-shaped [ 25 , 26 , 27 ] and star-shaped [ 28 , 29 , 30 ] polymers, dendrimers [ 31 , 32 , 33 ], block copolymers [ 34 , 35 , 36 ], and alternative copolymers [ 37 , 38 ]. These interesting structures and properties of POSSs make them widely used in hybrid materials [ 39 , 40 ], drug delivery [ 41 , 42 ], biomedical applications [ 43 , 44 ], catalytic supports [ 45 , 46 ], and so on [ 47 , 48 , 49 ], which have been reviewed extensively [ 47 , 50 , 51 , 52 ].…”

Synthesis and self-assembly behavior of pH-responsive star-shaped POSS-(PCL-P(DMAEMA-co-PEGMA))16 inorganic/organic hybrid block copolymer for the controlled intracellular delivery of doxorubicin

“…[11][12][13] Micelles could offer great potential and promising approach to deliver hydrophobic drugs into tumor site, which could improve the apparent water solubility and provide both passive and active targeting capabilities in order to enhance drug delivery efficacy and reduce drug side effects. [17][18][19] A typical POSS molecule, represented by the formula (R 8 Si 8 O 12 ), consists of a rigid and cubic silica core, 20,21 with a size in nano-scale, has also been widely investigated, since it can be introduced into polymer matrices to form hybrid polymers with thermal properties. 15,16 Moreover, inorganic/organic hybrid polymers have attracted a great deal of research interest, a particularly noticeable example is organic/inorganic hybrid polymers based on polyhedral oligomeric silsesquioxane (POSS).…”

“…Plenty of star-shaped polycations, POSS is containing a biocompatible core and display excellent performance in gene therapy. 29,30 Many well-defined hybrid polymers have been prepared using the living/controlled polymerization technique including hemitelechelic, telechelic and multitelechelic block hybrid polymers, 18,31,32 and controlled/living radical polymerization (CRP), 33 such as atom transfer radical polymerization (ATRP), 12,34 ring-opening polymerization (ROP), 35 click chemistry 36 and reversible addition-fragmentation chain transfer polymerization (RAFT). The eight corner organic groups can be easily modified into kinds of functional groups, such as amino, thiol, hydroxyl, and halogen 22,23 ， POSS has been shown to improve the biocompatibility in nano-composite materials.…”

“…A typical POSS molecule with a three-dimensional structure of the cage consists of a cubic silica core and eight organic corner groups around outside. 18,37 More recently, Zhang et al 38 synthesized a series of amphiphilic pH-responsive mPEG-b-(PLA-co-PAE) block copolymers with different PLA/PAE ratios for hydrophobic drug delivery, and the low CMC values of these copolymers could markedly improve micellar stability and extend the range of applications of micelles in controlled drug delivery. Lastly, POSS is able to disperse the cationic charges and thus facilitating gene transfection by lowering the cytotoxicity.…”