Poly(hydroxyl propyl methacrylate)‐b‐Poly(oligo ethylene glycol methacrylate) Thermoresponsive Block Copolymers by RAFT Polymerization

Abstract

their solubilization characteristics towards specific drugs. [4,5] The major advantage of AmBCs is that they can be prepared from a huge variety of different monomers in order to achieve the desired properties of the final AmBC chain according to the demands of specific applications. [10] An increasing number of copolymers possessing a stimuli-responsive block, responding to the alteration of its environment, [11,12] such as temperature, [6,9,13] pH, [3,14] or ionic strength, [4][5][6][7]14] has appeared in the literature, [3,4,15] The response (which in most cases leads to selfassembly) takes place when an AmBCs is dissolved in an aqueous medium. The phenomenon can be reversible, upon the variation of its environmental conditions (e.g., pH and temperature), [13] Thermoresponsive polymers show a distinct change in properties upon a large or small change in solution temperature. With regards to the thermoresponsive transition, depending on the system under investigation, there is a critical temperature at which segregation is due to the solvophobic block self-assembly, and in particular formation/disassembly of polymer aggregates in solution, [13,16] Thermoresponsive polymers are used for biomedical applications including drug delivery, [17] tissue engineering and gene delivery, [18,19] Materials with custom-designed responsive elements have the ability to significantly enhance the delivery of therapeutics agents. [17] In the center of interest of the present study is the development of new thermoresponsive AmBCs. The RAFT polymerization process has quickly become a powerful and versatile technique for the synthesis of a wide range of organic diblock copolymers and nano-objects of controllable size, morphology and surface functionality. This approach offers many potential applications, such as efficient microencapsulation vehicles and sterilizable thermoresponsive hydrogels for the cost-effective long-term storage of mammalian cells. [1] More recently, block copolymer self-assembly in solution to form spherical micelles, worm-like micelles and vesicles has been studied with potential applications in the field of drug, protein/peptide, and nucleic acid delivery. [1][2][3][4]13] In practice, relatively few vinyl monomers that may lead to thermoresponsive polymers have been tested for RAFT polymerization, such as N-isopropyl acrylamide (NIPAM), [7,14,[20][21][22][23][24] oligo(ethylene glycol) methacrylates, [25,26] vinyl-caprolactam, [27] and 2-hydroxypropyl methacrylate (HPMA). [1,21,25,28,29] In each case the corresponding Polymer Chemistry Thermoresponsive amphiphilic poly(hydroxyl propyl methacrylate)-b-poly(oligo ethylene glycol methacrylate) block copolymers (PHPMA-b-POEGMA) are synthesized by RAFT polymerization, with different compositions and molecular weights. The copolymers are molecularly characterized by sizeexclusion chromophotography, and 1 H NMR spectroscopy. Dynamic light scattering (DLS) and static light scattering (SLS) experiments in aqueous solutions show that the copolymers respond to temperatu...

Poly(oligoethylene glycol methacrylate) Star‐Shaped Copolymers with Hydroxypropyl Methacrylate Cores

“…High I 1 / I 3 values were obtained previously also for linear PHPMA‐ b ‐POEGMA copolymers, which proved the existence of hydrophilic domains in aggregated cores of these block copolymer aggregates. [ 47 ]…”

P(MMA‐co‐HPMA)‐b‐POEGMA copolymers: synthesis, micelle formation in aqueous media and drug encapsulation

“…49,50 The calculation of the composition for the statistical copolymer precursor (first block) was achieved by selecting the -CH 3 proton peak corresponding to the MMA segment (peak g, 3.6 ppm) and the -CH 2 proton peaks corresponding to the HPMA segment which appear at 4.08 ppm (peak c). 51 The procedure followed for finding the composition in the diblock copolymers was different due to the overlap of the peaks from the MMA and OEGMA segments (peaks f, g at 3.64 ppm). Peak i at 3.36 ppm was selected as the peak characteristic of OEGMA and peak c at 4.08 ppm was selected as the typical peak of HPMA.…”

Microfluidic Controlled Self-Assembly of Polylactide (PLA)-Based Linear and Graft Copolymers into Nanoparticles with Diverse Morphologies

“…For the self-assembly of the BCs in MF chips, Nemesys pumps (CETONI, Germany) were used (see Figure S1, in Supporting Information). The self-assembly process of the BCs PLA 35 -b-PTEGMA 64 and PHPMA 75 -g-PLA 35 was conducted at an initial solution concentration (C initial ) of 2.0 mg L −1 and PHPMAA 82g-PLA 35 at a C initial of 5.0 mg L −1 . The used concentration was chosen to prevent the formation of macroscopic aggregates within the MF chip.…”

“…The used concentration was chosen to prevent the formation of macroscopic aggregates within the MF chip. The PLA 35 -b-PTEGMA 64 and PHPMA 75 -g-PLA 35 copolymers were dissolved in THF, while PHPMAA 82 -g-PLA 35 was dissolved in THF/MeOH (80/20) (v/v). The polymer solutions were pumped through the middle channel, and miliQ water was pumped through the side channels using two separate liquid steams controlled via computer software.…”

“…The most well-known and extensively researched thermoresponsive polymer is poly- N -isopropylacrylamide) (PNIPAM), which has a lower critical solution temperature (LCST) in the range of 32–35 °C. , Human body temperatures are usually in the range of 35–37 °C, which makes it the most capable trigger system. Another example of thermoresponsive polymers are oligo(ethylene glycol) methacrylates, which allow precision tailoring of LCST dependent upon pendant chain length and end group and are believed to be biocompatible and suitable for drug delivery applications in a manner analogous to linear PEG, − 2-hydroxypropyl methacrylate (HPMA), and so on. Interestingly, PHPMA-based diblock copolymer NPs do not have a typical LCST profile, but they are weakly thermosensitive, which leads to shape-shifting behavior when adjusting the solution temperature .…”