Preparation and dispersibility of poly(L‐lactide)‐grafted silica nanoparticle

Abstract

To improve dispersibility of silica nanoparticle in organic solvents, the grafting of poly(L-lactide) (PLLA) onto silica nanoparticle surface by ring-opening polymerization of L-lactide (LA) was investigated in the presence of an amidine base catalyst. The ring-opening polymerization of LA successfully initiated in the presence of silica having amino groups (silica-NH 2 ) and an amidine base catalyst to give PLLA-grafted silica, but not in the presence of untreated silica (silica-OH). In the absence of the amidine base catalyst no ring-opening polymerization of LA even in the presence of silica-NH 2 and no grafting of PLLA onto silica were observed. It became apparent that the amidine base catalyst acts as an effective catalyst for the ring-opening graft polymerization of LA from the surface of silica-NH 2 . In addition, it was found that the percentage of PLLA grafting onto silica could be controlled according to the reaction conditions. The average particle size of PLLA-grafted silica was smaller than that of silica-NH 2 . Therefore, it was considered that the aggregation structure of silica nanoparticles was considerably destroyed by grafting of PLLA onto the surface. The PLLAgrafted silica gave a stable dispersion in polar solvents, which are good solvents for PLLA.

One‐Pot Formation of ZnO‐graft‐Poly(d,l‐Lactide) Hybrid Systems via Microwave‐Assisted Polymerization of d,l‐Lactide in the Presence of ZnO Nanoparticles

“…[ 10 ] A vast number of publications claim that a previous functionalization of the nanoparticles with hydroxy-or amino-ended molecules is generally required, followed by ROP of lactide catalyzed commonly by stannous octanoate. [4][5][6]8,[11][12][13][14][15] Several drawbacks arise from this process including a multistep hydroxyl-or aminofunctionalization reaction associated with a time-consuming procedure (several days) and the use of a tin catalyst leading to by-products (Sn(OH) 2 and SnO, among others) that are diffi cult to get rid of and potentially cytotoxic. [ 16 ] Therefore, there is a need for new methodologies to generate PLA-functionalized nanoparticles that involve innocuous initiation systems.…”

“…Recently, ROP has been used for the production of PLA‐grafted nanoparticles which in turn have been incorporated into commercial PLA matrices in order to obtain homogeneous nanocomposites with new or enhanced properties, such as conductivity, magnetization, bone regeneration, and mechanical performance . A vast number of publications claim that a previous functionalization of the nanoparticles with hydroxy‐or amino‐ended molecules is generally required, followed by ROP of lactide catalyzed commonly by stannous octanoate . Several drawbacks arise from this process including a multistep hydroxyl‐ or aminofunctionalization reaction associated with a time‐consuming procedure (several days) and the use of a tin catalyst leading to by‐products (Sn(OH) 2 and SnO, among others) that are difficult to get rid of and potentially cytotoxic .…”

Performance of Zinc Oxide Nanoparticles as Polymerization Initiating Systems in the Microwave‐Assisted Synthesis of Poly(d,l‐Lactide)/ZnO Nanocomposites

“…Poly(lactide) (PLA) is one of the most extensively investigated biosourced polyester, due to its biocompatibility, biodegradability, recyclability, and renewability . In order to extend its applications, PLA has been formulated with several nanoparticles, such as silica, graphene, and hydroxyapatite among others, whose incorporation has been achieved by in‐situ polymerization of lactide monomer, since it is considered as a versatile and effective approach to PLA‐based nanocomposites with well‐dispersed nanoparticles compared to melt‐mixing process (the most reported technique), which could be attributed to the lower viscosity in the former system reaction (at low‐medium monomer conversion).…”

Helicene‐Grafted Silica Nanoparticles Capture Hetero‐Double‐Helix Intermediates during Self‐Assembly Gelation

“…When the diameter of the silica particles is reduced to an anometer order,t he adsorption may still be promoted because of their large surface area. In addition, silica nanoparticles exhibit properties not observed in micrometer-diameter silica gels:1 )Silica nanoparticles can be suspended in an organic solution for ac onsiderably long period; [3] 2) Silica nanoparticles can aggregate and precipitate from the solution,w hich is initiated by the adsorption of small neutralo rganic molecules; [4] 3) Precipitationc an be conducted under the various conditions of the chemical reactions. [5,6] Note also that the properties of silica nanoparticles can be fine-tuned by loading different organic molecules on the surface of the particles.…”