scholarly journals Truly Random Degradable Vinyl Copolymers via Photocontrolled Radical Ring-Opening Cascade Copolymerization

2021 ◽  
Author(s):  
Wenqi Wang ◽  
Zefeng Zhou ◽  
Xuanting Tang ◽  
Stephanie Moran ◽  
Jing Jin ◽  
...  
Keyword(s):  
Sulfur Dioxide ◽  
Ring Opening ◽  
Main Chain ◽  
Radical Ring ◽  
Polymer Backbone ◽  
Vinyl Polymers ◽  
Powerful Approach ◽  
Chain Composition ◽  
Promising Solution

Degradable vinyl polymers by radical ring-opening polymerization have become a promising solution to the challenges caused by the widespread use of non-degradable vinyl plastics. However, achieving even distribution of labile functional groups in the backbone of degradable vinyl polymers remains challenging. Herein, we report a photocatalytic approach to truly random degradable vinyl copolymers with tunable main-chain composition via radical ring-opening cascade copolymerization (rROCCP). The rROCCP of the macrocyclic allylic sulfone and acrylates or acrylamides mediated by visible light at ambient temperature achieved near-unity reactivity ratios of both comonomers over the entire range of the comonomer compositions and afforded truly random vinyl copolymers with degradable units evenly distributed in the polymer backbone. Experimental and computational evidence revealed an unusual reversible inhibition of chain propagation by in situ generated sulfur dioxide, which was successfully overcome by reducing the solubility of sulfur dioxide in the reaction mixture. This study provided a powerful approach to truly random degradable vinyl copolymers with tunable main-chain labile functionalities and comparable thermal and mechanical properties to traditional non-degradable vinyl polymers.

TiCp2Cl-Catalyzed Living Radical and Ring Opening Polymerizations Initiated from Epoxides and Aldehydes in the Synthesis of Linear, Graft and Branched Polymers

2004 ◽  
Vol 856 ◽  
Author(s):  
Alexandru D. Asandei ◽  
Isaac W. Moran ◽  
Gobinda Saha ◽  
Yanhui Chen
Keyword(s):  
Electron Transfer ◽  
Ring Opening ◽  
Glycidyl Methacrylate ◽  
Ring Opening Polymerization ◽  
Branched Polymers ◽  
Single Electron Transfer ◽  
Radical Ring ◽  
Polymer Architectures ◽  
Complex Polymer

ABSTRACTTi(III)Cp2Cl-catalyzed radical ring opening (RRO) of epoxides or single electron transfer (SET) reduction of aldehydes generates Ti alkoxides and carbon centered radicals which add to styrene, initiating a radical polymerization. This polymerization is mediate in a living fashion by the reversible termination of growing chains with the TiCp2Cl metalloradical. In addition, polymers or monomers containing pendant epoxide groups (glycidyl methacrylate) can be used as substrates for radical grafting or branching reactions by self condensing vinyl polymerization. In addition, Ti alkoxides generated in situ by both epoxide RRO and aldehyde SET initiate the living ring opening polymerization of ε-caprolactone. Thus, new initiators and catalysts are introduced for the synthesis of complex polymer architectures.

scholarly journals Influence of cyclodextrin on the solubility of a classically prepared 2-vinylcyclopropane macromonomer in aqueous solution

2012 ◽  
Vol 8 ◽  
pp. 1528-1535 ◽  
Author(s):  
Helmut Ritter ◽  
Jia Cheng ◽  
Monir Tabatabai
Keyword(s):  
Aqueous Solution ◽  
Carboxylic Acid ◽  
Graft Copolymer ◽  
Ring Opening ◽  
Main Chain ◽  
Double Bonds ◽  
Radical Ring ◽  
Unsaturated Polymer ◽  
End Group ◽  
Clouding Point

A macromonomer 5 consisting of a polymerizable vinylcyclopropane end group and a poly(N-isopropylacrylamide) (poly(NiPAAm)) chain was obtained from amidation of 1-ethoxycarbonyl-2-vinylcyclopropane-1-carboxylic acid (4) with an amino-terminated poly(NiPAAm) 3 as an example. This macromonomer 5 showed an LCST effect after complexation of the vinyl end group with ß-cyclodextrin in water. Via radical ring-opening copolymerization of 5 and NiPAAm a graft copolymer 8 with a clouding point of 32 °C was synthesized. The branched unsaturated polymer was treated with ozone to cleave the double bonds of the main chain.

Main-chain degradable star polymers comprised of pH-responsive hyperbranched cores and thermoresponsive polyethylene glycol-based coronas

2018 ◽  
Vol 9 (39) ◽  
pp. 4824-4839 ◽  
Author(s):  
Ulrike Wais ◽  
Lohitha Rao Chennamaneni ◽  
Praveen Thoniyot ◽  
Haifei Zhang ◽  
Alexander W. Jackson
Keyword(s):  
Polyethylene Glycol ◽  
Ring Opening ◽  
Main Chain ◽  
Star Polymers ◽  
Hyperbranched Polymers ◽  
Ph Responsive ◽  
Radical Ring ◽  
Ketene Acetal

Dual stimuliresponsive main-chain degradable star hyperbranched polymers have been synthesized via cyclic ketene acetal radical ring-opening and RAFT-based methacrylate copolymerization.

scholarly journals Thiol-Substituted Poly(2-oxazoline)s with Photolabile Protecting Groups—Tandem Network Formation by Light

Polymers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1767
Author(s):  
Niklas Jung ◽  
Fiona Diehl ◽  
Ulrich Jonas
Keyword(s):  
Ring Opening ◽  
Network Formation ◽  
Uv Light ◽  
The Novel ◽  
Thiol Groups ◽  
Polymer Backbone ◽  
Repeat Units ◽  
In Situ Gelation ◽  
Spatio Temporal

Herein, we present a novel polymer architecture based on poly(2-oxazoline)s bearing protected thiol functionalities, which can be selectively liberated by irradiation with UV light. Whereas free thiol groups can suffer from oxidation or other spontaneous reactions that degrade polymer performance, this strategy with masked thiol groups offers the possibility of photodeprotection on demand with spatio-temporal control while maintaining polymer integrity. Here, we exploit this potential for a tandem network formation upon irradiation with UV light by thiol deprotection and concurrent crosslinking via thiol-ene coupling. The synthesis of the novel oxazoline monomer 2-{2-[(2-nitrobenzyl)thio]ethyl}-4,5-dihydrooxazole (NbMEtOxa) carrying 2-nitrobenzyl-shielded thiol groups and its cationic ring-opening copolymerization at varying ratios with 2-ethyl-2-oxazoline (EtOxa) is described. The tandem network formation was exemplarily demonstrated with the photoinitator 2-hydroxy-2-methylpropiophenone (HMPP) and pentaerythritol tetraacrylate (PETA), a commercially available, tetrafunctional vinyl crosslinker. The key findings of the conducted experiments indicate that a ratio of ~10% NbMEtOxa repeat units in the polymer backbone is sufficient for network formation and in-situ gelation in N,N-dimethylformamide.

Biocompatibility and Physiological Thiolytic Degradability of Radically-made Thioester-functional Copolymers

2022 ◽  
Author(s):  
Nathaniel Bingham ◽  
Qamar Nisa ◽  
Priyanka Gupta ◽  
Neil Young ◽  
Eirini Velliou ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Ethylene Glycol ◽  
Ring Opening ◽  
Degradation Products ◽  
Nile Red ◽  
Functional Polymers ◽  
Radical Ring ◽  
Vinyl Polymers ◽  
Temperature Responsive ◽  
Copolymer Micelles

Being non-degradable, vinyl polymers have limited biomedical applicability. Unfortunately, backbone esters incorporated through conventional radical ring-opening methods do not undergo appreciable abiotic hydrolysis under physiologically relevant conditions. Here, PEG acrylate and di(ethylene glycol) acrylamide-based copolymers containing backbone thioesters were prepared through the radical ring-opening copolymerization of the thionolactone dibenzo[c,e]oxepin-5(7H)-thione. The thioesters degraded fully in the presence of 10 mM cysteine at pH 7.4, with the mechanism presumed to involve an irreversible S–N switch. Degradations with N-acetylcysteine and glutathione were reversible through the thiol–thioester exchange polycondensation of R–SC(=O)–polymer–SH fragments with full degradation relying on an increased thiolate:thioester ratio. Treatment with 10 mM glutathione at pH 7.2 (mimicking intracellular conditions) triggered an insoluble–soluble switch of a temperature-responsive copolymer at 37 °C and the release of encapsulated Nile Red (as a drug model) from core-degradable diblock copolymer micelles. Copolymers and their cysteinolytic degradation products were found to be non-cytotoxic, making thioester backbone-functional polymers promising for drug delivery applications.

Functional Poly(p-Xylylene)s via Chemical Reduction of Poly(p-Phenylene Vinylene)s

2019 ◽  
Author(s):  
Ain Uddin ◽  
Weifan Sang ◽  
Yong Gao ◽  
Kyle Plunkett
Keyword(s):  
Film Formation ◽  
Chemical Reduction ◽  
Water Soluble ◽  
Phenylene Vinylene ◽  
Polymer Modification ◽  
Polymer Backbone ◽  
Crosslinking Process ◽  
Conducting Membranes ◽  
In Situ Crosslinking

The synthesis of poly(p-xylylene)s (PPXs) with sidechains containing alkyl bromide functionality, and their post-polymer modification, is described. The PPXs were prepared by a diimide hydrogenation of poly(p-phenylene vinylene)s (PPVs) that were originally synthesized by a Gilch polymerization. The polymer backbone reduction was carried out with hydrazine hydrate in toluene at 80 °C to provide polymers with the sidechain-containing bromide functionality intact. To demonstrate post-polymer modification of the sidechains, the resulting PPX polymers were modified with trimethylamine to form tetraalkylammonium ion functionality and were evaluated as anion conducting membranes. While PPX homopolymers containing tetralkylammonium ions were completely water soluble and not able to form valuable films, PPX copolymers containing mixed tetraalkylammonium ions and hydrophobic chains were capable of film formation and alkaline stability. In addition, an in situ crosslinking process that used N,N,N',N'-tetramethyl-1,6-hexanediamine during the tetraalkylammonium formation of brominated PPX polymers was also evaluated and gave reasonable films with conductivities of ~10 mS-cm-1.

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